/ohm/ - electronics general

[Anonymous No.1581590]

the old thread has reached the bump limit: >>1576405

>RULES
0. Electrics ≠ electronics. Home appliances/sparkies to /qtddtot/ or /sqt/. PC assembly to >>>/g/.
1. Do your own homework. Search web first. Re-read all documentation/datasheets related to your components/circuits. THEN ask.
2. Pics > 1000 words. Post relevant schematic/picture/sketch/9001.5 hours in MS Paint with all part numbers/values/etc. when asking for help. Focus/lighting counts.
3. Read posts fully. Solve more problems than you create.
4. /ohm/ is an anonymous, non-smoking general.

>I'm new to electronics, where to get started?
It is an art/science of applying principles to requirements. Find problem, learn principles, design and verify solution, build, test, post results, repeat

>Project ideas:
http://adafruit.com
http://instructables.com/tag/type-id/category-technology/
http://makezine.com/category/electronics/

>Principles (by increasing skill level):
Mims III, Getting Started in Electronics
Platt, Make: Electronics
Geier, How to Diagnose & Fix Everything Electronic
Kybett & Boysen, All New Electronics Self-Teaching Guide
Scherz & Monk, Practical Electronics for Inventors
Horowitz and Hill, The Art of Electronics

>Design/verification tools:
LTSpice
falstad.com/circuit/circuitjs.html
NI Multisim
CircuitLab
iCircuit for Macs
KiCAD (pcb layout software, v5+ recommended)

>Components/equipment:
Mouser, Digi-Key, Arrow, Newark, LCSC (global)
RS Components (Europe)
eBay/AliExpress sellers, especially good for component assortments/sample kits (caveat emptor)
Local independent electronics distributors
ladyada.net/library/procure/hobbyist.html

>Related YouTube channels:
mjlorton
jkgamm041
eevblog
EcProjects
greatscottlab
Photonvids
sdgelectronics
BigClive

>Li+/LiPo batteries
Read this exemplary resource first: https://www.robotshop.com/media/files/pdf/hyperion-g5-50c-3s-1100mah-lipo-battery-User-Guide.pdf
>I have junk, what do?
Take it to the recycler.

[Anonymous No.1581591]

>>1581590
Starting the thread with a question: how do I manage this mess? I have very limited space, pretty much only the table itself with a drawer. Is that even possible?

[Anonymous No.1581596]

>>1581591
looks fine to me
could use more ziplock bags

[Anonymous No.1581598]

>>1581591
Build a shelf above the table
Use parts organizers

[Anonymous No.1581609]

>>1581537

[Anonymous No.1581668]

still haven't worked out how I'm going to ground all these odd IC pins
should I just abandon trying to keep it clean?

[Anonymous No.1581698]

taking shape

[Anonymous No.1581707]

>>1581591
>>1581596
this. maybe some anti-static bags or some conductive foam

>>1581563
large print edition

>>1581668
you need more surface area. fold-out wings on your "bench" for lightweight stuff would be great
maybe something like baking sheet trays would help. I can personally confirm that they are great for not losing small parts like SMD passives

[Anonymous No.1581716]

>>1581609
you don't need to care about the value of the output wrt ground, just the voltage across the cap. so you can delet the zener, it won't do anything for you that the cap won't do

[Anonymous No.1581726]

>>1581698
You are funneling your autism in the right direction, anon.

[Anonymous No.1581727]

>>1581698
>wire at all odd angles
you don't like orthagonal wires?
and why are they all different colours?
and what's with the button spacing? are they supposed to be spaced like that?

[Anonymous No.1581772]

Should I really use the EN pin of an LDO like in pic related or I can get away with a switch that cuts off the battery itself?

[Anonymous No.1581775]

>>1581772
you can switch EN, if you're willing to accept the quiescent current draw of the regulator and there is an internal or external pull-down on EN
you should switch EN if size or other limitations restrict you from including a switch big enough to carry the current of the load and the regulator, OR if you're using a step-up converter without true load disconnection
otherwise you can get away with interrupting the battery itself

[Anonymous No.1581780]

I just got these battery packs for $2.75ea. What should I do with them?

>inb4 poop hole
I already did that with the clearance Kobalt ones, and those were 6 cells so I don’t see much of a challenge in trying the 18v packs.

[Anonymous No.1581784]

>>1581780
Stockpile cells for an electric bike or something? Spot welder?

[Anonymous No.1581787]

>>1581784
I was still thinkin about trying to build a jumper pack for the car. There was 3rd battery pack too, I shoulda grabbed it but I only took 2.

They have this second contact part. I stuck the DMM probes in the regular slots and got 7.8V, thought I just wasted $6. Then I hit the little charge level button and got 19.8V. The two on top were 0.0V, then I hit that battery indicator button and got 5.0V. I could charge a cell phone off that bitch.

Now I need to figure out what makes it go from 7.8V to 18.9V and 0V to 5V. The little cell phone power banks were like that too and BigClive has a video where he shows you just short the + and - data leads for a second to get full power.

[Anonymous No.1581789]

>>1581739

[Anonymous No.1581791]

>>1581787
Oh a jumper pack is a good idea, but I'm unsure how easy it would be to make or buy the circuitry for.

I wouldn't necessarily trust those 5V and 7.8V levels, chances are those are high-impedance and plugging a phone or something in would quickly have them drop below 1V. First I'd figure out the pinout / what each contact is supposed to be for, and possibly even try to trace out the existing PCB, or at least its wide power traces.

[Anonymous No.1581796]

Fixed for ya

[Anonymous No.1581798]

>>1581791
Shorting CHR+ to 12V+ made it jump up to 18V, so that must be the key to getting power from it like those power banks.

I don’t understand why thay’s labeled “12V” though. I don’t get any power from it, only thing is seems to do is turn the thing on from 7.8V to 18.9V, and turns the ID + COM from 0.0 to 5.0.

Oh and for plans, I have one of those buck-boost converter boards from Amazon and I was thinking about wiring that up to make a cheap power supply if I’m afraid of destroying my real one.

[Anonymous No.1581802]

Oh and related to the USB and 18V battery packs...

For the USB coming out of a power bank, the power pins read like 300mV or something until you short the two data pins. So for my retarded light project with the power going through the power bank board, what’s the best way to do this? Should I run Vcc into a switch, and then out of the switch I have Vcc going to the light, plus another wire to Data -? Maybe I gotta search through more Big Clive, from the clip I saw he just had to short out the Data + and - for a split second and it seemed to remain on as long as whatever device was still drawing power. I think Vcc to Data - will do the same thing but I’m curious if it will assplode if I do it for more than a split second.

Same with that drill battery, and I just run 18V+ to that 12V(data?) pin to get it to switch on? Like I run 18V+ to an on/off switch, and then two wires coming out of the switch, one to the device and another one to the 12V(data) so when I flip the switch on to power whichever device, it also shorts that shit so 18V+ goes from that 7V to fill power.

[Anonymous No.1581804]

>>1581590
I was thinking about getting that same gps module, would you recommend it?

[Anonymous No.1581806]

>>1581591
do you have a harbor freight nearby?

https://www.harborfreight.com/40-bin-organizer-with-full-length-drawer-94375.html

[Anonymous No.1581813]

Has anyone tried 3d printing dupont connector shells. I was considering buying a .2mm nozzle and seeing how it went.

[Anonymous No.1581814]

>>1581804
Works much better than a chinese clones, the hot startup is about 10 seconds. Depending on the weather, can actually fix inside of a room.

Be aware that it needs at least 3.6v to work reliably. OR you could just de-solder the onboard LOD and replace it with 0 resistor, like I did, then you would be able to feed it with 3.3

[Anonymous No.1581815]

>>1581814
What are you making kneegrow?

[Anonymous No.1581817]

>>1581813
good god why when they're cheap as chips

>>1581814
don't respond to newportfags

[Anonymous No.1581819]

I wouldn't usually respond, but for sake of others I would rather recommend to ignore the faggot above.
tripfags/avatarfags do not contribute anything of value to the conversation, but only tickle their ego by baiting (you)s.

[Anonymous No.1581821]

>>1581791
Damn, I’m trying to think about this jumper pack, it would need to be pretty beefy as far as wiring and connections. Other route would be a buck converter, this one is rated at 20A. If I stacked a handful of 18650s, maybe like a dozen of them together (6S2P?) and set it for a 14V-15V @ 10A, smoke a couple cigs while it’s hooked up and maybe it would give the battery enough juice to crank her over...

[Anonymous No.1581823]

>>1581817
They are only cheap when you order 3 months in advance though. I wish there were more images but this is the 3d print I was looking at.
https://www.thingiverse.com/thing:3067259

[Anonymous No.1581825]

>>1581590
>>Components/equipment:
Any Chileans here? Where can I buy all this junk locally?
I don't want to wait 3 month...

[Anonymous No.1581826]

>>1581823
kawaii

[Anonymous No.1581830]

sup /ohm/. Just getting into electronic shit, just ordered a soldering iron and a bunch of little chink shit LED boards to practice on

What I'm unsure about is a power source to test those. Do I really need to buy a $50+ power source just to test these, or do I have a cheaper option?

[Anonymous No.1581832]

>>1581830
The power supply is fun. But I just posted the other thing, you can get a buck-boost converter from Amazon for $10-$20 and it will work pretty well. This one isn’t as accurate as the power supply, but it seems to be within like 0.2V/A. I believe this one takes 5V-30V DC input, so it will run off one Li-Ion but not as accurately. Works well off this 18V drill battery pack. You could probably run it from a 9V battery or a USB charger hacked apart but might be limited to lower currents.

[Anonymous No.1581833]

I found 3 19V laptop SMPS in junk/recycler. They seem to be in working condition.
What should I do, before plugging them in the wall.
What should I do with them?

[Anonymous No.1581834]

>>1581830
for your purposes, you can buy one of those little step-down converter boards and run from an old laptop PSU. hell, buy ten, they're cheap (not even kidding)

[Anonymous No.1581837]

>>1581833
>I have junk, what do?
take them back to the recycler

[Anonymous No.1581838]

>>1581837
Nope. Never ever.
I got entire fully working printer from there for free.
I think I can sell those for $5 on ebay, considering the fact that they aren't chink noname, but well-certified OEM Delta and HIPRO.

[Anonymous No.1581842]

>>1581727
dunno
they're pre-cut to specific lengths
and yeah the buttons are correct, I need a block of 5, 2 and 2

[Anonymous No.1581843]

>>1581832

Like I said, I'm not real knowledgeable on this shit just yet. Let me make sure I'm getting this.

The buck-boost converter can hold a charge from a lithium ion battery, and then use that charge to power something else? In my case, the chink LED board. I've got a similar battery pack you have pictured for a weedeater, so I imagine that might work the same. Appreciate the help homie

[Anonymous No.1581844]

>>1581838
Fucking pieces of shit.
Why they don't put discharge resistors in those?

[Anonymous No.1581845]

[Anonymous No.1581846]

>>1581780
Portable variable dc power supply that can be recharged. Add battery level indicator, displays for voltage and current, etc. It would be an awesome tool.

[Anonymous No.1581847]

>>1581843
It doesn’t hold a charge, it just lets you convert the power from the battery to different voltage and current. The battery hooked up to that converter is almost the same thing as the power supply in your pic (but not as accurate so double check with your meter). The battery takes the place of the wall plug sort of. Or even grab a cheap power supply from a laptop or whatever like this anon said >>1581834 , I have some 12V/3A power supplies from old cable boxes that could plug in.

Buck converters lower voltage, boost converters raise voltage. Basic buck or boost converters are really cheap but not as easy to adjust as that $15 one with the screen.

[Anonymous No.1581852]

>>1581846
There’s an AvE where somebody did basically the same thing and mailed it to him. It’s a Makita battery and it looks like dude used the same type of converter as me, hacked up one of these USB chargers and/or 3D printed a little case to make it all neat, and then had two outputs for the banana plugs. Would be fun to make if I had the printer to make a good case for all of it, would work great assuming the battery pack has an overdraw protection built in.

[Anonymous No.1581857]

>>1581846
>>1581852
Here’s the one the redditor made

[Anonymous No.1581860]

>>1581847

Sweet man, thanks. I'll probably get the one you've got in your pics

[Anonymous No.1581868]

>>1581844
How Do i discharge mains caps? I melted my screwdriver accidentally

[Anonymous No.1581874]

If I want to get into electronics more so than just replicating someone else's design, do I need an oscilloscope.

[Anonymous No.1581877]

>>1581874
if you want to build a circuit
that does something interesting
you have already designed and simulated it and know how it will behave
and you don't get it absolutely correct first time
or you just want to see how close it is irl to the sim
then yeah its necessary
but otherwise its very useful anyway.

[Anonymous No.1581879]

>>1581845
made me look you fucker

>>1581868
a large resistor (100kohm 5W should be enough for anything, even doubled 240V), some clips, some heatshrink, and a few minutes

>>1581874
it helps a lot, though if you're working heavily in the digital domain you will probably find more value in a logic analyzer. some scopes (in particular the popular Rigol DS1054Z) have some basic-tier logic analysis like serial protocol decoding available as software features, which in the Rigol case just means you use a keygen
scopes are also essential for repair work, in case you want to make a little money on the side

[Anonymous No.1581883]

>>1581879
I'm about to order one of those $8 logic analysers off ali, so I'll report on its behaviour once it arrives.

[Anonymous No.1581886]

>>1581879
Hm. Can I use multi meter to discharge caps?

[Anonymous No.1581951]

>>1581886
Yes, but it's kinda shitty. Rectified mains on a cap will be ~340VDC or ~170VDC, so to get 1W for example (a reasonably modest power) you'd want ~120kΩ or ~30kΩ respectively. If you know the capacitance you can figure out how long this will take to discharge: t = 5*R*C. Assuming 1mF capacitance, this makes it 600s or 150s respectively, which is quite a while. A DMM has a resistance of either 1MΩ or 10MΩ, both of which will mean a much longer time than either of those posted. The better part of a day in the worst case scenario. I'd use a power resistor, such as:
>10W 12kΩ, 1 minute at 340V 1mF, 15 seconds at 170V 1mF
>25W 5kΩ, 25 seconds at 340V 1mF, 6 seconds at 170V 1mF
>50W 2k5Ω, 12.5s at 340V 1mF, 3 seconds at 170V 1mF
Your capacitance may be larger or smaller however, and don't touch the resistors while they're doing their thing, good recipe for a burn. Nichrome wire in a bucket of water should be able to handle a hundred watts or so, provided you can get an appropriate length.

[Anonymous No.1581960]

About to plug mains into a breadboard circuit, wish me luck!

[Anonymous No.1581964]

>>1581960
Shit I forgot continuity between the neutral line to the other two diodes where the capacitor used to go.

[Anonymous No.1581965]

>>1581886
if you like exploding multimeters, sure. send video

[Anonymous No.1581972]

>>1581960
>>1581964
ok it worked without issues

[Anonymous No.1581992]

>>1581972
oops, just tripped the RCD

[Anonymous No.1582000]

>you should never mount a through-hole resistor vertically

[Anonymous No.1582001]

>>1581960
>>1581992
OK testing finished. So I've got two bridge rectifier power supplies, one inside my driverless LED, the other in my perfboard zener circuit, and I've tested and confirmed that both have diodes running from their negative rail to both AC inputs. I measured between these negative pins with my DMM and read a significant AC voltage (36V) and a significant DC voltage (6V), but since this isn't too high for my scope and it's on a probably isolated PSU, I persevered. My experiments culminated in whacking my shitty scope between these two pins and I saw a 6V ripple, which I thought was surely too high to be just from differing diode drops. Noticing this was less than the AC voltage my 10MΩTrue RMS meter measured, I decided that it might be a high-impedance voltage that will not be a problem when I short them in the final circuit. So I whacked a 200kΩ resistor across them, and it dropped a bit, then a 6k8Ω resistor, which brought it to the 4V ripple you can see in this image. The scope probes are in parallel with the resistor if that wasn't clear.

So would it be fine to short these two? I still haven't a clue where this ripple is coming from. Should I try a smaller resistor? The RMS is perhaps 0.5V, so I could technically go down to 1Ω or so, assuming I had such a resistor.

>>1582000
Eh, I'm probably going to with these big 1W resistors because they take up too much room otherwise. Who'd say that anyhow?

[Anonymous No.1582002]

>>1582001
I wasn't replying to you you dumb fucking redditor. also your soldering is shit

[Anonymous No.1582003]

>>1582000
said no chinky boombox maker ever

[Anonymous No.1582004]

>>1582002
I know you weren't replying to me, it didn't look like you were replying to anyone in particular at all since there was no mention of vertical resistors in the thread. It looked like an open statement intended for anyone in the thread to reply to, so I gave my cent and a half. Not sure how you can infer much about my soldering from the poorly lit photo, but those few components at the side do have a distinctly flat fillet. The connection is still fine since the through-holes are plated, but if I were to do the project again and had ample solder to use I'd probably try and get some semblance of well filleted joints, as they add some mechanical-stability. Still, they were all soldered from the back and it's a pain constantly flipping the board over to check how far down the solder went, so for the most part I just wing it. Also your grammar is shit.

[Anonymous No.1582012]

>>1581716
I had problems with overshooting voltage when i had 1mH inductor, thats why i added the zener. it seems you're right though, it doesnt do anything now.
>>1581638
yeah, that was what i thought. the only way to use a smaller inductor is by increasing the switching frequency. no wonder converter ICs switch at MHz speed.

[Anonymous No.1582028]

>>1582001
I'll be trying lower and lower resistances to see how this ripple behaves, and I might try classifying it thevenin-style.

[Anonymous No.1582029]

>>1582012
> I had problems with overshooting voltage when i had 1mH inductor
The energy stored in the capacitor needs to be much larger than that in the inductor:
(1/2)*L*I^2 << (1/2)*C*V^2.

[Anonymous No.1582031]

does Pic related chap anyone else's almonds?

[Anonymous No.1582036]

>>1581802
each manufacturer uses different charging schema. some simply short the data lines, you can short them forever it won't do shit, others require specific value voltage dividers bewteen datas and power pins, this is on purpose so you are forced to buy brand chargers for faster charging

[Anonymous No.1582048]

>>1582028
Ok I tested with some more resistors and decided to just plug the two together. It didn't work, which was almost as frightening as when I brushed a wire in the wrong place and my scope went blank. Then I swapped the power supply to be in the correct direction and it started working. Then the on-off button didn't work. Then I traced it to a broken solder joint, fixed that, and now it works flawlessly. Except for some flicker, but I think I can fix that with some shielding and such. I guess I'll make sure the right wires are soldered in place and will epoxy over where I'll be needing strain relief onto the COB.

I recently found a couple of 90V neon indicator bulbs in my parts bin and realised they'd make good indicators for the light, but I'm split on whether to make them a "light is on" indicator, a "light is plugged in" indicator, or a "remote/button is being pressed" indicator. I'll need to turn on the neon with a low-side FET on the 340V rectified rail, likely with a 680kΩ resistor in series. Anyone have opinions on this matter? I think I'd prefer the "button being pressed" idea, but that's an active low signal, so I'd need an inverting transistor. A "light is on" indicator would be somewhat redundant but it would help me differentiate when the dimmers have been set to minimum from when the light has been turned off with the button/remote. The "light is plugged in" indicator could serve as a good safety feature, which for a homemade mains appliance is arguably the most necessary aspect. Going for all three is an option however, and I do have access to blue and green neons, which I could tie in nicely with the R,G,B potentiometers on the front panel.

[Anonymous No.1582049]

>>1582029
I've added the zener back. I also changed the transistor from shitty signal (beta 80m) to decent power (beta 10, very conservative). After changing the transistor beta, it seems that the voltage overshoots if I step up the duty cycle too fast. Also, I tried changing the output cap to bigger values (up to 100mF), but it still overshot and I don't want to damage my fan.
Another problem with quick step up in duty cycle is the current from the source shoots way the fuck up (up to ~8A) and the zener triggers dissipating huge amount of energy (90W for ~1ms), see pic related.
In reality, my power supply is only able to supply ~3A and there's a bunch of other stuff connected to it. Will this damage my power supply? Will stepping up quickly fry the zener diode? Or are these spikes only visible in simulation due to idealized components (0Ohm inductor, etc.)?

[Anonymous No.1582053]

>>1582049
What does beta mean in the context of a mosfet?

[Anonymous No.1582055]

>>1582053
I'm not even going to pretend that I understand this, it's obvious I'm a brainlet when it comes to electronics.
lush has a small calculator for beta here: lushprojects.com/circuitjs/mosfet-beta.html

[Anonymous No.1582058]

>>1582055
Is that supposed to be a useful value? Can't see what you'd use it for.

[Anonymous No.1582060]

>>1582058
My understanding is that it's basically the resistivity of the mosfet. Small values increase dissipated power, slow down current during step ups and increase voltage drop across the mosfet.

[Anonymous No.1582061]

>>1582058
In SPICE it's transconductance

[Anonymous No.1582067]

>>1582049
sorry for spamming, but I found these four pin fans. if I understand correctly, the pins are Vcc, GND, tachometer and pwm control.
if I understand correctly, I should be able to just supply pwm straight from lolduino to fans pwm pin and control the ground with small mosfet?

[Anonymous No.1582069]

>>1582067
Yes. Should we have mentioned those earlier?

[Anonymous No.1582070]

>>1582067
>>1582069
Oh not sure what you mean by "control the ground with small mosfet" though, it shouldn't need any of that, just the PWM signal.

[Anonymous No.1582073]

>>1582069
I guess so, I haven't heard about these before. I knew about 3pin with tachometers, but not these 4pin.
>>1582070
I found a datasheet of one of these 4pin fans (AUB0912VH-CX09). It says that even at 0% duty cycle the fan will spin at it's lowest speed. I need to be able to shut the fan completely off, that's why I want to additionally control GND with a mosfet.

[Anonymous No.1582074]

>>1582073
Ah, I guess that FET make sense. Odd how the thing keeps running though, that may not be common to all 4-wire fans should you decide to look at different models.

[Anonymous No.1582075]

>>1582067
Yep, 5V PWM ideally within 21-28kHz frequency.

>>1582073
Some fans will stop at 0%, some will just hold a minimum speed. If you want to force stop MOSFET on ground + make sure PWM signal is low should be alright.

[Anonymous No.1582076]

>>1582075
He could make a capacitor + schmitt trigger circuit from his PWM line to his FET so only if the PWM line is off for longer than a PWM period or two will the FET actually cease to conduct. Assuming he isn't doing shit in software anyhow.

[Anonymous No.1582078]

>>1582076
they're already using a lolduino so doing it in software is ez

[Anonymous No.1582083]

>>1581775
Thanks

[Anonymous No.1582130]

>>1581960
fuse?

[Anonymous No.1582149]

>>1582073
I have a smaller 2-wire SUNON fan that has 12V 1.1W and an operating range of 6V..13.8V. At less than 4VDC it draws very little current, about 0.3mA. I did a test with a simple TLC555 PWM circuit and used pin 7 for the switching. No external mosfet, simple RC filter. Cycle time is constant 330µs (3kHz). The fan starts up at ton=70µs (21%) and stops when less. No whining at all. At ~100% you hear the typical sound of a small fan running at high speed.

[Anonymous No.1582172]

So, I am still learning verilog and I was trying something like this:

always @(posedge clk) begin
x <= 1;
end
always @(negedge clk) begin
x <= 0;
end

But I get an error: net 'x' has multiple drivers.
Is there a way to to manipulate variables in verilog on multiple clocks or posedges / negedges of signals.

[Anonymous No.1582216]

>>1582172
Why would you punish yourself like this?
Anyway, MATLAB has a HDL coder that is helpfull. My pirate version has it. I'll never use it tho because FPGAs are cancer. Also, /g/ has a programming thread.

[Anonymous No.1582226]

>>1582172
>>1582216
brainlets

[Anonymous No.1582235]

>>1581698
what's this going to be?

[Anonymous No.1582249]

Say you have a high voltage circuit with two relays, like pic related

In which order would you close the relays (first 1 and then 2, or vice versa) in order to cause least damage to the relays?

Also, in which order would you afterwards open the relays? This question is more important, while I think the first question is insignificant

I can't find any literature on this but logic says the (2) relay should be closed first due to direction of the electrons

[Anonymous No.1582253]

>>1582249
>I can't find any literature on this but logic says the (2) relay should be closed first due to direction of the electrons
current flow and also the voltage across the open relay is the same for either scenario.

[Anonymous No.1582255]

>>1582249
>I can't find any literature on this but logic says the (2) relay should be closed first due to direction of the electrons

You are either a terrible troll or you need to forget about electronics and go into something like baking.

[Anonymous No.1582257]

>>1582253
yes but built up capacity and transients and something something

[Anonymous No.1582267]

>>1582257
please assign yourself a name or a trip so I can filter your posts
thanks, have a great day

[Anonymous No.1582272]

>>1582249
Electrons (or holes) move with near light speed. You don't even need two relays, one will suffice.

[Anonymous No.1582301]

>>1582172
combine the two edges into a single driver. as long as there are no other signals in your sensitivity list you will then have a block that is double-edge clocked
>always @(clk)
> if (clk)
> x <= 1;
> else
> x <= 0;
too lazy to see if this synthesizes

>>1582216
>/g/
yes, please go back

[Anonymous No.1582303]

>>1582272
>Electrons (or holes) move with near light speed.
EM waves do, electrons do not. Look up drift velocity.

[Anonymous No.1582309]

>>1582303
I know, it's just the matter of abstraction, it is easier to imagine a moving electrons than actually go down the details and do waves. At the end of the day it doesn't matter.

[Anonymous No.1582311]

>>1581965
>can stick probes in mains and nothing will happen
Why cap will make something happen
>>1581951
Indeed. But what about resistance mode?

[Anonymous No.1582312]

>>1582130
I have a PTC lying about, but I planned on using it for another project and I can't find the rest of the bag I bought them in. So maybe.

>>1582311
Resistance mode would probably kill your DMM unless it's well built. Current mode would be like melting a screwdriver inside your DMM.

[Anonymous No.1582332]

>>1582309
I don't agree. That abstraction breaks down immediately when you try to think of what electrons do when there is more current: "light speed electrons" don't somehow go any faster.
Electron drift really is proportional to current and fits the hydraulic analogy better IMO.

[Anonymous No.1582334]

>>1581868
Knife? Back of your hand, nails, your other screwdriver etc..

[Anonymous No.1582335]

>>1582332
>I don't agree.

And what device or design that you work with does this actually matter? for the clown up there with two relays, the action is instantaneous for all practical purposes.

>inb4 I design magnetrons.

[Anonymous No.1582341]

>>1582309
Abstraction =/= error. Electron mobility, wave dynamics are really important things.

[Anonymous No.1582367]

How do those wireless voltage detector wands work?

[Anonymous No.1582369]

>>1582367
Mine works capacitively.

[Anonymous No.1582370]

>>1582335
So it was a deliberate lie, Mr. Straw?

[Anonymous No.1582372]

>>1582332
Yes, the rate at which pressure propagates in the hydraulic analogy (the speed of sound) suits the rate at which the electric field propagates in wires. More proof that the hydraulic analogy is top shit.

>>1582367
Capacitive coupling, same reason why measuring the AC voltage from yourself to ground will give you a reading of a couple of volts; your body acts like an antenna for mains electricity. Use that potential to trigger a MOSFET or other high input-impedance sensor and you've got a working sensor. Though in their case they measure the potential from your body to right near the outlet, as there will be a difference.
But you could also make a magnetic one by measuring the voltage across an open inductor instead of measuring the electric field between your body and the air close to the antenna.

[Anonymous No.1582373]

>>1581591
Creation is an inherently messy business.
So long as no one else is giving you shit about it and you're happy with however you decide to organize things, then it's all good.
Bosses tend to want it to look like you're not doing any actual work, though -- then they give you shit for looking like you don't do any work.

[Anonymous No.1582376]

>>1582334
That is redneck method, that killed my screwdriver.
>>1582312
It is unfused, so yeah.

Anyway, 3/4 PSU I found in literal trash are working. One has a big hole in PWM IC, I didn't notice, and I don't want bother repairing it, so it goes back to the trash.
What should I do with three working SMPS that give out 18-19V 1.58A/ 3.16A?
How good does TS-100 perform at 19W? Or should I use Hakko-T12 controller?

[Anonymous No.1582378]

>>1582376
19W is a bit shit for any iron, I'd get a dedicated PSU if you already have the iron. Else get one of those chinese T12 stations, they're pretty good value for their price, at least certainly more so than a TS-100 or TS-80.

[Anonymous No.1582379]

>>1582378
I meant 19V. Feel dumb now
According to datasheet it will draw 2.1A and that is ±40W

[Anonymous No.1582381]

>>1582379
40W isn't awful, plus 19V is I think the recommended voltage for one of those meme irons (the TS-80 I think) but I think you'd still be better off powering an iron/station with at least 60W.

[Anonymous No.1582392]

>>1582381
>powering an iron/station with at least 60W.
I know. I never had a soldering station.
I used to have CXG 60W Hakko 900 iron, but I moved to other country and still didn't ship my shit.
Now I use fixed power 30W cheap-o iron, it kinda works, but man, I hate conical tips... Really, where do you use conical tips?

Problem is that all cheap soldering stations are chinkshit garbage. I still haven't found a decent one, while those meme irons are relatively cheap and pretty high quality (compared to some stations).
And I really liked buttons on my CXG thingy.
>TS-80
It is only 18W.

[Anonymous No.1582394]

>>1581825
anyone?

[Anonymous No.1582397]

>>1582392
The knockoff hakko stations have a pretty good rep here, and I've personally got a T12 station and I've not had a single problem with it. It comes in an aluminium case with its own switch mode power supply and you can fully customise sleep/off times, standby, run, and boost temperatures, plus a little control flexibility. I bought it after watching a few reviews, one of which claimed it was better than his legit Hakko station. Which isn't terribly surprising considering the guys are still building the damn things with century-old ordinary transformers for their power supply.

[Anonymous No.1582398]

>>1582397
Also a big fan of the cheapo T12 OLED stations, heater in tip is nice. T12-K best tip. Recent legit Hakko stuff with the two button UI is real annoying compared to a dial.

[Anonymous No.1582400]

>>1582397
900-series copies are awful.
But T12 stuff seems to be good.
>. Which isn't terribly surprising considering the guys are still building the damn things with century-old ordinary transformers for their power supply.
Chinks 900 stations have them too, and they are underpowered. Voltage sags (which is common in shitholes), stations starts glitching.
With SMPS this is not an issue (to some extend).
Original 900 Hakkos tho, aren't as bad as clones, but I'd still get a CXG.

So yeah, I think I'd get T12 station, original Hakko handle, and knock-off heaters/tips.
But what about hot air? I used everything else, like gas torch, heat gun, halogen projector... But it all kinda suck.

[Anonymous No.1582405]

>>1582398
>-K tip
My nigger.
It is the best tip. It has some thermal mass, and it can do everything.
>SMD
>Though hole
>Tin ghetto PCBs
>Massive grounds
>Scrapy-scrapy.
Also, it is the cheapest tip, since everybody else is getting dental pics or -B and -BC types.

[Anonymous No.1582421]

>>1582400
I'm no expert on hot air. There is a T12-style hot air station out there, and there's also a T12 combination station, but I've no way of telling if they're any decent.

>>1582405
I think it's the cheapest because everyone buys it and the distribution routes are more open. Heck, it's the one tip my station came with. Though I have actually heard from a guy that the legit Hakko tips are significantly better, not sure if he's a shill or not.

Anyone own one of those inert gas soldering stations? They blow nitrogen over your soldering iron so shit never oxidises. Not sure if they do that with hot air too though.

[Anonymous No.1582444]

>>1582421
>I think it's the cheapest because everyone buys it and the distribution routes are more open. Heck, it's the one tip my station came with
All people I know, they hate -k tip. And chinks won't put most common tip.
>Though I have actually heard from a guy that the legit Hakko tips are significantly better, not sure if he's a shill or not.
Tips don't last in my hands, so I think I'd go for knock off.

[Anonymous No.1582447]

>>1582444
>Tips don't last in my hands
I've never burnt through a single tip before burning through the iron's element (was on seperate tip-element irons until buying my T12), what are you doing to them? The apparent advantage with the legit tips was that they have very optimised thermal characteristics, even heat flow to all of the tip, etc. The guy was shilling the K tips in particular, never seen anyone diss those but eh different circles.

[Anonymous No.1582452]

>>1582447
>what are you doing to them?
Weird shit.
First of all, I used really shitty rosin, which oxidizes those tips like nothing.
Now I use plumbing flux, since it is cheaper, but shit is conductive. It is more aggressive, but for some reason it doesn't eat through those tips. Also I use 50/50 solder, not 60/40. No difference at all.
Also I scrape solder mask, and PCBs are abrasive enough to fuck up the tip after some time.

[Anonymous No.1582454]

>>1582452
I use an old x-acto knife for scraping solder mask, lead-free solder, and a big tub of rosin paste. I tried out a no-clean-flux pen, but I keep going back to the rosin since it works so much better. It's apparently name-brand made in USA stuff.

[Anonymous No.1582500]

In an RL low pass filter, how much of an effect does the resistance of the inductor have on the circuit?
I'm working on a speaker crossover, and one of the inductors that it calls for is rated at 1.0mH and has a DC resistance of 0.17 ohms, while the inductor that I have on hand has a resistance of 0.6 ohms.

[Anonymous No.1582502]

>>1582500
compared to the weirdness of the speaker's impedance it's negligible

[Anonymous No.1582511]

>>1582502
Thanks, I honestly had a feeling, but some of the people on certain audio forums seemed to be insistant on using certain components, & I wasn't sure if it was just lack of experience/audiophoolery or if there was really a reason.

[Anonymous No.1582512]

>>1582500
The resistance of a speaker is typically 4 or 8 ohms, so a difference of 0.5 ohms isn't insignificant.

Also: check the inductor's maximum current rating. The relatively-high resistance suggests that it probably isn't intended for high current.

[Anonymous No.1582547]

>>1582500
Why do speaker crossovers use resistors anyhow? Wouldn't it make sense to just have two LC filters in parallel?

[Anonymous No.1582550]

>>1582376
I never saw someone melt a screwdriver with capacitors. Do you mean the plastic somehow heated up or the steel melted? I just short the terminals with a chonky resistor or short them with the closest metal object.

[Anonymous No.1582552]

>>1582376
Also, get the inductors out of that PSU man. You can always find them use.

[Anonymous No.1582559]

>>1582547
The "resistor" in the RL is the speaker

[Anonymous No.1582560]

>>1582149
no idea what you meant here. I have a couple of ne555 laying around, but I never got around learning how to use them.
anyways, looking at some sample circuits, it looks more complicated than my shitty buck converter. I'm also not quite sure how to control the duty cycle of 555 with lolduino. would i need another filter to filter out the voltage of lolduino pwm and input it to 555 threshold?

[Anonymous No.1582561]

>>1582560
Weekend experiment

[Anonymous No.1582568]

>>1582049
>Another problem with quick step up in duty cycle is the current from the source shoots way the fuck up (up to ~8A) and the zener triggers dissipating huge amount of energy (90W for ~1ms), see pic related.
>In reality, my power supply is only able to supply ~3A and there's a bunch of other stuff connected to it. Will this damage my power supply? Will stepping up quickly fry the zener diode? Or are these spikes only visible in simulation due to idealized components (0Ohm inductor, etc.)?
>>1582561
that was the idea when i bought those 555s a year ago. unfortunately i have 20 other weekend experiments going. maybe one day...

[Anonymous No.1582573]

>>1582559
Oh? In some speakers I opened up there was one inductor (not toroidal), one capacitor, and one ~5W resistor. The speakers were 8Ω. Can't see the capacitor in this image, but I assure you there was one.

[Anonymous No.1582576]

>>1582049
>93W
that'll prolly fry it
>overshoot
that inductor at that frequency gives you ~450mA of ripple. if your load only consumes 200mA, well, E=I*R isn't on your side here. if you want less current ripple (therefore less overshoot) you'll need a larger inductor, like 10mH. I recommend a soft start instead, should be easy to do in software

>>1582573
yeah, that's a crossover

[Anonymous No.1582577]

>>1582576
> I recommend a soft start instead, should be easy to do in software
yeah, that was my backup plan. increasing the size of the inductor is really out of the question, even 220uH is physically huge.

[Anonymous No.1582579]

>>1582573
resistance can be used to reduce levels

[Anonymous No.1582580]

>>1582576
>yeah, that's a crossover
I know, crossovers were the entire topic of conversation in the first place, but that doesn't really answer my question.

>>1582579
Sounds like a bit of a waste when you have a purpose-built amplifier.

[Anonymous No.1582595]

>>1582550
Steel just vaporized. Just tiny 50µF cap at 220V.
>>1582552
Sure. And transformer.
Everything else would go back to recycler..

[Anonymous No.1582596]

>>1582595
310V, fix.

[Anonymous No.1582598]

>>1582547
one reason might be to make the transfer curve less steep

>>1582595
>transformers
meh, they're almost certainly high-frequency and you'll never find a datasheet. get an L meter and a scope if you want to play with them, otherwise return to sender

[Anonymous No.1582601]

>>1582598
>L meter and a scope
Bah, if nothing else it's a source of a fuckton of enamel wire. Chances are you can just find the datasheet of the main switching controller and figure out the rest with some simple resistance measurements.

>>1582595
>Just tiny 50µF
>stares at 400V 1mF capacitor sitting on desk
ehehehe

[Anonymous No.1582622]

>>1582580
getting good balance between the drivers when they're in their full low/high/band pass region matters, easiest way to do that with a shared input is being lossy

[Anonymous No.1582627]

I just read this StackExchange article:
https://electronics.stackexchange.com/questions/284086/mems-or-other-modern-component-electroscopes
And it rekindled my interest in electroscopes. In particular, the measurement of absolute charge, like how a simple gold leaf electroscope works with but a single electrode. And I don't believe the modern electrometers can do this because they use a bias current in order to perform their measurement, even if it's in the realm of femtoamps, because there shouldn't be anywhere for that current to flow to. From wikipedia:
>a modern electrometer is a highly sensitive electronic voltmeter whose input impedance is so high that the current flowing into it can be considered, for most practical purposes, to be zero
Which almost by definition has two electrodes.

So I want to measure the charge of the Earth, or more precisely, the net charge as measured from a ground rod. A gold leaf (or MEMS) electroscope hooked up to a ground rod would show deflection of the two pieces as a function of the charge's magnitude (actually volumetric charge density I think) as the like charges within the two pieces repel one another. Is there any way to replicate this "absolute charge measurement" with FETs or other modern technology? Perhaps measurement of the planet's DC electric field, or the gradient of this field? But then that would be somewhat effected by charges in the upper atmosphere, unless Gauss's law is about to bite me on the head for that assumption. I think I'm still somewhat right provided the charge distribution isn't uniform, which it likely isn't.
Presumably an electrometer or even a moderately sensitive voltmeter could measure the voltage across two capacitor plates and therefore measure the voltage between them, which provided you're somehow free from the all-permeating 60Hz whine would give you a value for dE/dz which could be exchanged for a total Q value with the help of the inverse square law and the radius of the Earth.
cont.

[Anonymous No.1582636]

>>1582627
But that still isn't as simple as the gold-leaf electroscope, nor does it measure the same thing (charge density vs absolute charge). And one measurement can likely not be interchanged to the other since the charge densities will be non-constant. Naturally a gold-leaf electroscope won't show a value without a charge source as strong as a bit of carpet-sock triboelectricity, so trying to use one on the planet would be a bit silly. But in the case of a spacecraft passing through the Van-Allen belts, there will be a very real net charge buildup and it could be very useful to measure this. I imagine most methods would rely on the inner capsule itself remaining isolated and hence at a similar potential to the home planet itself, but this would increase the spacecraft's risk of suffering a sudden discharge/arc from the outside to the inside.

Thoughts?

[Anonymous No.1582682]

>>1582598
>meh, they're almost certainly high-frequency
Getting ferrite cores is expensive. Here it is free.
>>1582601
When I was in school, I found somewhere a paper capacitor (600v 4 uf I guess)... It was a fun shoker

[Anonymous No.1582693]

I want to get back into electronics and I figured having a power supply would be pretty essential.
Was thinking about getting a Korad KA3005P (€110) but it's only single channel 30V 5A.
Pic related, the KA3305P, is 3 channel which seems much more useful (5V for powering microcontrollers and the others for powering analog stuff), but that's over twice as expensive at €230.
That's a lot of dough for something I'll just use for fucking around with electronics a bit. Is it really worth it?

[Anonymous No.1582694]

>>1582693
forgot pic

[Anonymous No.1582815]

>>1582693

https://www.youtube.com/watch?v=Cw2AjcczHg4
EEVblog #1030 - $20 DIY Bench Power Supply!

it's just plugging some modules together. any beginner can do it.
and you dont need a fixed 5V output coz you can use phone chargers and the like, at $1.50 each from the thrift store.

[Anonymous No.1582822]

>>1582815
still requires a power supply or a beefy transformer

[Anonymous No.1582832]

>>1582822

like Dave says, ''if you dont have some power brick for a laptop, or something, you're just not trying"

[Anonymous No.1582835]

>>1582512
>Also: check the inductor's maximum current rating. The relatively-high resistance suggests that it probably isn't intended for high current.
Any way to fid this out if it's a salvaged inductor without any markings? I got the inductors out of some trashed speakers that I found on the side of the road that allegedly were rated at 125w, and the crossover I'm making is for some bookshelf speakers that are rated for 50w.

[Anonymous No.1582836]

>>1582822

like Dave says, ''if you dont have some power brick for a laptop, or something, you're just not trying"

[Anonymous No.1582837]

I've to lay out a pretty simple circuit on stripboard.
I usually do the layout myself using graph paper to design it.
I've had a very long week and my loud ass faggot family are here for the weekend so I can't concentrate long enough to do this shit.

Anyone know any software that can lay out a stripboard using a schematic?

[Anonymous No.1582838]

>>1582832
Laptop power bricks are around 12-15V. That minus the dropout that module has is pretty low.
Might as well use an old ATX power supply and a 2$ buck module.

[Anonymous No.1582846]

>>1582838

nope, laptop supplies are actually 16-20V. however, that's not relevant as those units will step up the voltage. you only need 4-6V on the input.

as for ATX supplies, they can pump like 60-100A temporarily into your circuit so are dangerous for noobs. you're much safer with the current limiting those modules have.

[Anonymous No.1582851]

>>1582846
You must be talking about a different module.
The one in the video is step-down only.

[Anonymous No.1582856]

>>1582822
Meh, I did come across that vid. Interesting enough for various purposes, but it doesn't seem very user friendly and since I'm mainly interested in building guitar pedals for now I want a clean power source, which I doubt a cheap chink power supply will be. A linear power supply is probably a lot less noisy.

[Anonymous No.1582859]

>>1582851

oh, didnt see the disclaimer text placed over the video at 2m35s.

[Anonymous No.1582861]

>>1582856

this is all you need for pedals. all linear. and you probably have some from your old home phone.

[Anonymous No.1582862]

>>1582856

this is all you need for pedals. all linear. and you probably have some from your old home phone.

[Anonymous No.1582864]

>>1582862
Yeah lol, technically I could get away with that, but I also want to do other stuff (microcontrollers, drive motors, study components and circuits, etc) so having a variable power supply seems very useful.
Already got a nice (crt) scope and a bunch of shit. I dicked around with microcontrollers a couple of years ago using a wall wart and power bank, which was fine for digital stuff. Just never got around to getting a decent variable power supply, which seems pretty useful when doing analog stuff.

[Anonymous No.1582867]

>>1582856
nothing that a bit of LC or even RC can't clean up. your effects should be able to consume 15V with minor or no modifications. add a 7809 post-regulator if you're extra concerned

>>1582837
I heard of something called VeeCAD a few threads ago

[Anonymous No.1582891]

What sort of wire should i use for a part that is moving around, so the wire is constantly bending?

[Anonymous No.1582898]

>foxhole radio
>no power source on board
>gets its power from the radio signal

So, what about a UHF foxhole radio that receives and uses bluetooth as its power source and data carrier? I know it'd be bulk as fuck, but as proof of concept it should work right?

[Anonymous No.1582899]

>>1582898
no. the laws of physics called and they said they hate you and won't show up to your funeral

[Anonymous No.1582900]

>>1581590
I have a bit of a hardware question: I bought a Raspberry Pi W and want to make a weather station out of it, but I can't seem to search/find the "Hardware" such as a basic temperature probe, wind spinner (or however it can be called), barometer, etc.

As I basically want the components to a basic pin-out , it could really be used for any application instead of adding onto a raspberryPI, but yea - Looking for something that isn't "Already Built" .
anybody bought parts as such before or can suggest a quality place?

[Anonymous No.1582903]

What do you guys think would be a good budget for a second hand oscilloscope for a first time user?

[Anonymous No.1582904]

>>1582899
Well, it works for RFID at least. There's at least someone on the tubes who has done it.

[Anonymous No.1582912]

>>1582903

150-200 USD, or 48,300-64,400 Zimbabwean Dollars

[Anonymous No.1582915]

>>1582836
Wtf I can do with power bricks?
I found 4 of them in trash, and 3 of them are actually working.

[Anonymous No.1582917]

>>1582915
read the thread instead of just posting, I'm sure you'll think of something

[Anonymous No.1582919]

>>1582903
Around 50 bucks should get you a decent used analog scope. Or if you get lucky you can sometimes get one for free, like me. They're old but still great for most stuff, especially for a beginner.

[Anonymous No.1582923]

>>1582915
If they are not gunked up with goo inside, there can be a lot of nice parts and usually you can fix the non-working ones pretty easily with a soldering iron and a spare $0.10 part at worst.

[Anonymous No.1582930]

>>1582915
>Wtf I can do with power bricks?

besides power supplies, i use them for
- hot wire foam cutter
- power 2 thin client computers used as as media centers
- power 18V drills with dead batteries (i use 2 in parallel for more power - using diodes for a wired OR)
- power some 24V ikea LED cabinet lamps

[Anonymous No.1582948]

>>1582903
Depends on what kind of scope you want. You can get a lower spec analogue one that is still very usable for $30, and better ones will cost you slightly more. It depends on where you live and where you are buying though.

[vent anon No.1582962]

maybe im in the wrong general.
a few days ago i came to ask about fixing the motor in my vent. an anon guided me on what to buy, and i got the part today and self installed in under five minutes with a butter knife. it works and i want to say thank you to anon and /diy/

t h a n k y o u

[vent anon No.1582963]

thanks again anon
thumbs up

[Anonymous No.1582972]

>>1582963

you're welcome. if i suspected you were female, i'd have asked for a tit pic. dont feel slighted if i failed to do so.

[Anonymous No.1582974]

>>1582972
>female
>tit
...well...
ill take the blue board ban and hope your actually the anon that helped me
<3

[Anonymous No.1582978]

>>1582974
>blue board ban

There is nothing BUT "blue boards" on this whole site anon.

[Anonymous No.1582979]

>>1582974

so now all my time spent helping noobs on /diy/ is worthwhile.

[Anonymous No.1582980]

how 2 do

[Anonymous No.1582983]

>>1582980
something like this, using rail-to-rail op amps (MCP6002 would do nicely)

[Anonymous No.1582984]

>>1582980

http://www.learningaboutelectronics.com/Articles/Square-to-triangle-wave-converter-circuit.php

personally i'd make an integrator using an op-amp (like the pic), but you can start with a simple RC filter (as in the link.)

[Anonymous No.1582985]

>>1582983
>>1582984
Intredasting, thanks for your prompt and informative input bros

[Anonymous No.1582997]

>>1582985
RLC networks are the building blocks for analog electronics, like learning your times tables in maths. if you can understand how these three components work, look into the physics of it, you will understand filters and thats basically all there is to analog. and also digital is analog in disguise, so its real important. if you want to learn. maybe you don't i'm just saying. plenty of people learn about resistors and kind of skip over L&C. especially L

[Anonymous No.1583095]

Hope its alright for me to ask this here because I can't find a single good application for this (there probably isn't), but what can I do with pic related? Just store random stuff in it for fun?

[Anonymous No.1583104]

>>1583095
No you can't do anything cool or fun with it. It's flash memory, what do you expect?

[Anonymous No.1583128]

I see people designing power supplies for nixies every now and then, but looking at a few IN-series datasheets tells me that 170V is the kind of voltage they need. Wouldn't simple rectified (and filtered) mains suffice for this? Seems to me you could make a very simple nixie clock with this in mind, plus timing based off synchronising with mains frequency and a cheap little transformer/buck converter or even zener dropper to power the electronics' few mA need.

[Anonymous No.1583198]

>>1581802
>>For the USB coming out of a power bank, the power pins read like 300mV or something until you short the two data pins.
it depends on the power bank. this isnt required for devices, its just a way some cheap power banks detect if something has been plugged in. If you are making your own 5v power bank, you dont NEED to have it read data pins at all - you can just add a switch or even just have it always output 5v

[Anonymous No.1583199]

>>1581821
should you be dumping 20Ah into an SLA? that might be a bit much...

[Anonymous No.1583200]

>>1583199
To start a motor you need up to a few hundred amps. Not sure if that's buffered in the SLA, you'd have to look at how existing solutions do it.

[Anonymous No.1583204]

>>1582031
why would it?
if you are salty they are charging more for the pcb, they had to design the pcb, have it manufactured and assembled (also paying for the components). I doubt they made 10 million pcbs to get the cheapest price too. so its probably a similar profit margin for them.

t. chinaman

[Anonymous No.1583205]

>>1583204
>if you are salty they are charging more for the pcb
They're charging less for the PCB you fucking insectoid

[Anonymous No.1583206]

>>1583200
the typical charging rate of an alternator is about 5A. at 20A, you would potentially be liberating a lot of hydrogen, which is not good for the battery, and I think I'd take that smoke well away from the car
discharging, otoh, doesn't liberate hydrogen gas. if the plates get warm for a second, well, that's duty

[Anonymous No.1583208]

>>1583206
Well if you were pumping it straight into the starter motor things would be different, but you're right about not wanting that much current into your battery. Just to get the energy to fire the starter motor I assume you'd either need to charge the battery for a while (a minute or two?) or have it set up such that when the starter motor fires the SLA voltage will drop and the lithium ion circuit will provide most of the current.

[Anonymous No.1583210]

>>1582864
find an old lappy charger (usually 19v, 5A) and grab a cheap variable buck\boost converter from china. you can pop it all in a case with some banana plugs and big pots to adjust voltage (fine and coarse). will be way cheaper, a nice little project to work on, super serviceable since you made it and should be around 100w)...want multiple outputs? just get a few more cheaper ($1) bucks for lower voltages.
theres also the PC PSU videos where they take a generic computer power supply, add a buck\boost (some just use the straight 3.3, 5 and 12v outputs) and call it a day.

If you do make it yourself, you can tailor it to how you want it. add features other supplies dont have, choose the size and layout etc

[Anonymous No.1583213]

>>1581821
cars aren't that picky about voltage. drop the electronics entirely and build a 3S?P pack with thicc straps and connect directly to the car as normal

[Anonymous No.1583212]

>>1583205
Do you have mental issues? The price of the bare chip is $0.23 pull your eyes out your ass.

[Anonymous No.1583214]

>>1583212
Not him but you don't seem to be familiar with Ali's interface. That's the price per piece. So your min. order of 10 pieces is actually 23$

[Anonymous No.1583215]

>>1583212

[Anonymous No.1583216]

>>1583212
It said "$2.30 / piece" even though it says "10 pcs/lot" in the description, which is odd. Either could be correct, but it's likely to be the 10. Sorry to bother you.

[Anonymous No.1583217]

>>1582948
>>1582912
>>1582919
I've decided to go with this one. Probes included and for a decent price, about 35 euros.

[Anonymous No.1583218]

>>1583217

[Anonymous No.1583219]

>>1583218
excellent choice

[Anonymous No.1583222]

So tried making a spot welder, I'm giving up because the goal for this project was not buying shit and using 0$.
>400uF 400 V capacitor
>~310 rectfied mains
>god knows how much current
>no input switch, input is limited by a 10W 10 ohm resistor and a 5W 220V lamp.
Most switches I've used have failed, probably due to fusing, I thought the very large current would only happen in a short time, so they wouldn't be damaged but I was wrong and I'll need to put several in parallel. But as I have no clue of the output current, I don't know how many I need to put in and errors will end up with lots of bricked expensive switches
Tried
>IGBTs (IRGP 50B60 PD1)
>Line voltage mosfets (now I see why mosfets are only a good idea on low voltages)
>Triacs
Most of them with peak currents on the range of 100-500A.

[Anonymous No.1583223]

>>1583215
>>1583214
The fact that this item has no orders indicates that the seller most likely just messed up with item settings so it came up $2.3 instead of $0.23. Because why the hell would he buy a roll of fucking 100'000 pieces and then sell them for that price?

[Anonymous No.1583224]

>>1583217
yeah that should do just fine, philips made good scopes, I have one myself

[Anonymous No.1583226]

>>1583224
Nice. Now all I need is a good desoldering station and a hot air station and my kit is complete.

[Anonymous No.1583227]

>>1583223
for reference, Digi-Key price for (10) ADS1115 is $49.62
other ali sellers sell the chip for about $2 each. yet the breakout boards can still be found for around 30-50 cents less than the main chip on them. wtf

>>1583222
for a spot welder, you need low voltage, high current. otherwise you get sparks and splatter even if you don't get switch fusion. probably several 100A MOSFETs in parallel, or SCRs?

[Anonymous No.1583229]

>>1583222
The problem will be arcing; by trying to seperate two contacts that have high-current DC through them you'll just create an arc that erodes the contacts as long as it lives. Try a circuit breaker as your switch, or a thyratron or something. Personally I'd charge up capacitors to store only the energy you'll need to use, so you don't need to shut off the current.

[Anonymous No.1583236]

>>1583227
>>1583229
Yeah, I tried low voltage "high" current with 30V with caps ammounting to 2mF. Turns out that is way too low.
>sparks and splatter
uhm, maybe that is why it doesn't work very well at mains.
>>1583229
I think the other guy is correct, the voltage is too high and the current, to low. Arcing at 220v? most likely not. I put 2 filament lamps in series with the input, so I could test it without bothering with a input switch.

[Anonymous No.1583238]

>>1583236
Now I'm trying to thing of the cheapest quickest way to make a step down xformer that does not involve a microwave oven.

[Anonymous No.1583239]

>>1583236
you need farads
stop playing MacGyver, take everything to the recycler and buy the right tools for the job, because you clearly have no idea what you're doing and a complete incapacity to research

[Anonymous No.1583241]

>>1583236
Arcing at 220VAC won't happen much because the current cuts off every half wave, but if you look at mains switch contacts you'll see pitting from small arcs. If you rectify mains you should definitely be able to sustain an arc over 1mm or so. You'd still get pitting either way.

>>1583238
Microwave oven. Basically free at the dump, or a roadside or commercial skip/bin. Or a bunch of caps in series that you then switch to be in parallel. There's not really a particularly easy method to doing that one however.

[Anonymous No.1583246]

>>1583239
nearly graduating EE student here. Got the IGBTs as scrap from the lab. I'm just too chickenshit to measure this stuff and break my only instruments.
>>1583241
Thanks m8. I'll see if I find an xformer or make my own with a spare iron core I have here, but just to think of winding coils again I get a backache.
>>1583241
>Or a bunch of caps in series that you then switch to be in parallel.
Never crossed my mind to make the "reverse" of a voltage multiplier. I think that's doable albeit phisically larger.

[Anonymous No.1583247]

>>1583246
>hurr durr anyone can be anything on the web
welp, who cares. Never fussed arround with power stuff until now. Always was focused on electronics and control

[Anonymous No.1583248]

>>1583246
>winding coils
Well good luck with that.

[Anonymous No.1583249]

>>1583246
MOTs are split-bobbin. you cut off one winding and put like 3 turns of big ass cable onto the core in its place

[Anonymous No.1583275]

have a project i'd like some advice on.

I have some cables that read temperatures, from what i can tell they are ds18b20 sensors hooked up in parasite power mode(around 6 per cable). I'd like to bring all these readings to a PC in the house. From one end to the other is ~200m, but the power supply could be added in the center. There are about 30 cables to connect to.

Getting the readings themselves is not difficult, but I'm having trouble deciding on how to bring the readings into a central location and how to power the readers. I would like to stick with a single run of cat5 on a bus system to avoid pulling a ton of cable.

My thoughts right now was to go with something like RS485, and use the remaining 2 pairs for 12 or 24v dc device power. Or maybe I should just go with PoE equipment but the cost seems significantly higher.

[Anonymous No.1583298]

I'm trying to design an H bridge, but it's turning out to require many components. Can somebody recommend me a single channel, 8pin, SMD H-bridge driver that van handle up to 30V for less than 1$ each? The smaller the footprint the better.
For the life of me I haven't been able to find something with those parameters.

[Anonymous No.1583306]

>>1583298
DRV8801, around 70cent per piece on Ali, handles up to 36V and 2.8A, SSOP.
But is 16pin.

[Anonymous No.1583314]

>>1581772
I think that EN thing is for when you're controlling it with a MCU.


Hello again, /ohm/ buddies. Does anyone in here use Fiverr to sell custom pcb designs?

Also, does anyone know why LCSC doesn't send components with JLC's pcbs anymore?

>>1581823
Heatshrink is way better than the little dupont housings in my opinion

[Anonymous No.1583316]

I want to make a "cold lava lamp" out of quinine water and UV LEDs.

Where can I buy potting compound that isn't super expensive?
And also (I know this isn't strictly electronics), how can I increase the viscosity of a liquid without changing its optical properties/making it cloudy, so I can suspend stuff like glitter in it

[Anonymous No.1583317]

>>1583316
Big Clive made a few videos and articles about how to make something like that.

[Anonymous No.1583319]

>>1583317
son of a bitch, I thought I was being original.

[Anonymous No.1583360]

>>1583218
>>1583217
spot looks nice, you should be good. be carefull about vertical scale: I got an old metrix which gone totally mad after a few years, misleading me in my work.

[Anonymous No.1583369]

>>1582561
>Weekend experiment
>>1582568
>that was the idea..

Result with L = 1mH (Rs=3Ω), C = 100µF, cycle time 340µs (2.94kHz): Fan starts up at ton = 40µs, toff = 300µs (duty cycle = 12%). Start-up tested by stopping the fan by hand. DC voltage across motor 4.2V at start-up and 11.4V at 100%.

[Anonymous No.1583372]

Can I make a version of this circuit so that it fits inside a credit-card sized PCB and is powered by a 3v coin battery? I mean, the answer is obviously yes, but do I need to change anything in order to make it work?

[Anonymous No.1583380]

>>1583372
no

[Anonymous No.1583388]

>>1582891
stranded obviously

[Anonymous No.1583393]

>>1583372
> credit-card sized PCB
Aside from the battery, there's no need for that circuit to be larger than about 5mm x 5mm.

[Anonymous No.1583420]

Even though I can't contribute much (as I'm still a beginner), I want to say that this is one of the best generals on 4chan(nel) and I appreciate the help I've received so far from all of you.

[Anonymous No.1583440]

>>1583393
I want to make one of those "useful PCB business cards". Since I'm an architect, why not a card that will let people find mains wiring through walls?

[Anonymous No.1583442]

>>1583440
Also, yes I know that smd transistors are really small because I've made a lot of things with them

[Anonymous No.1583445]

>>1583314
>does anyone
no but I saw a guy doing it. highish-speed designs, too
>Also, does anyone know why LCSC doesn't send components with JLC's pcbs anymore?
also interested. I really wish I did. took some of the value out of ordering from LCSC

>>1583442
if you can find a way to get that 9V, I don't see why you should have much trouble doing that

[Anonymous No.1583475]

>>1583372
>Can I make a version of this circuit so that it fits inside a credit-card sized PCB and is powered by a 3v coin battery?
I doubt it.

https://www.electronicshub.org/non-contact-voltage-tester/

[Anonymous No.1583507]

>>1583217
Looks good. I have a Philips scope myself, but yours is in way nicer condition.

[Anonymous No.1583512]

>>1583372
>darlington-style array
>not just a single FET
But yeah the main problem will be powering the thing. If you can get it to work like a crystal radio and be self-powered that would be ideal, but I'm unsure how much power you can get out of mains like that; whether 1mA for an LED would be a stretch.

[Anonymous No.1583519]

I kinda regret dropping out of EE 10 years ago to study CS instead. CS is cool and all but I now realize electronics are more interesting.
I'll take comfort in the fact that I probably couldn't have handled EE anyway, being the brainlet that I am. Now I'm relegated to simply being an amateur dicking around with electronics.

[Anonymous No.1583527]

>>1583475
You can actually. But I'd use super cap and USB for thinness.
Also I'd probably replace BJTs with some sort of mosfet.

I did this shit, when I needed to find wire in wall, worked good enough.

[Anonymous No.1583530]

>>1583527
a couple of springy leaf contacts plus a cutout in the board would make a fine battery slot. a supercap wouldn't last very long tbqh, prob not long enough to honestly use. attention to detail is a key part of a business card, even for goofy gimmicks
>hurr yup I do lettronics
>can't dimension a power supply

[Anonymous No.1583533]

>>1583530
You can actually buy 3V lithium batteries with spot welded contacts for thinness.
Considering this would be a novelty, it would last for some time.

[Anonymous No.1583538]

>>1583533
Plus a CR2015 cell would be thin enough to fit in a circular hole in the PCB.

[Anonymous No.1583539]

>>1583538
Sure, it is not a problem as long as you're ordering PCBs.
I think it will look something like this.

[Anonymous No.1583541]

>>1583539
I think you can also make a cut out for button.

[Anonymous No.1583544]

perfboard or stripboard

[Anonymous No.1583546]

>>1583539
Yeah, though I think the capacitive sensing requires a ground reference on the other end, for which a few conductive pads for your hand to touch would suffice. Pic related, though I'm somewhat unsure what resistor values you'd pick. 10M would probably be sufficient for R1, R2 could go with 10k or so. But the problem is your body is capacitively coupled to the ground rail but also to a lesser extent to live; measuring myself now I'm about 3.3VAC to ground and 70VAC to live (I guess there's some resistance between the part of me acting like an antenna and my DMM probe that makes it not add up to 240) so you'd need to make it sensitive but not too sensitive. Tuning R1 would probably be how you'd get this balance right.

>>1583541
He has one

[Anonymous No.1583547]

>>1583546
Idk, it worked for me without touching anything.
But im in 220V shithole.

[Anonymous No.1583551]

>>1583547
It was probably capacitive coupling from the circuit to your hand, which is likely good enough.

[Anonymous No.1583552]

>>1583551
I wasn't touching anything at all, It would detect cable under the table with capacitive coupling desk provides.

[Anonymous No.1583553]

>>1583552
No I mean your body is for the most part acting like an antenna to ground, and by putting your hand very close to the circuit you'd be indirectly coupling the circuit's voltage rail(s) to ground.

[Anonymous No.1583561]

>>1583539
Green is my CAD

[Anonymous No.1583570]

>>1583561
Indeed.

Anyway, how can I steal electricity from phone line?
I have a power outage right now, and it sucks to have no lights. One LED light will flash from 50V? line, others won't turn on at all.
What can I do?

[Anonymous No.1583574]

>>1583533
>sure I'll just put this in my metal business card pocket-box

>>1583553
capacitor to ground, maybe

>>1583570
look up the Chartreuse Box

[Anonymous No.1583580]

>>1583570
>One LED light will flash from 50V? line, others won't turn on at all.
The loop is current limited.
Usually 60ma at a few volts.
The more current you attempt to draw, the lower the voltage will be.

[Anonymous No.1583583]

>>1583574
A CR2015 cell is 1.5mm thick, which is about the thickness of a moderate/thin PCB. Insetting it within the PCB and he won't have a single issue.

[Anonymous No.1583588]

>>1583580
>The loop is current limited.
Yes, they have a fuse/fusible resistor on line. I tried shoring a line, and after that I called service and pretended that I dindu nuffin.
I think I can remove LED driver from lamp and connect diodes directly for some light, so I don't mispiss in toilet

[Anonymous No.1583590]

>>1583583
contacts will be about 0.05mm thick, and you'd probably need two. you'd have to be careful with layout and to use short capacitors so that you could depend on the SOT-23 bodies keeping the supply from shorting anywhere

[Anonymous No.1583594]

>>1583588
Lol. LED light will work at 40-50% brightness from phone line, but I needed to shunt 1-2 diodes.

[Anonymous No.1583595]

>>1583594
I hope that fusible resistor doesn't blow up...

[Anonymous No.1583597]

>>1583594
try paralleling them to eat up all the current

[Anonymous No.1583598]

>>1583590
You could put all the SMT components inside gaps carved in the PCB, a bit like the old flatpacks. Pic related.

[Anonymous No.1583603]

>>1583597
I wish I could... I don't have butane soldering iron, nor USB meme, and twisting two is nearly impossible I guess.

[Anonymous No.1583604]

>>1583598
ooh, that's gonna cost extra

>>1583603
twist the supply wire around them instead

[Anonymous No.1583605]

>>1583604
>ooh, that's gonna cost extra
Not if you solder yourself anyhow

[Anonymous No.1583607]

>>1583604
Hm. I think current is maxed anyway.

[Anonymous No.1583608]

>>1583607

[Anonymous No.1583610]

>>1583607
as long as you can see okay, bro
stay safe

[Anonymous No.1583613]

>>1583610
Sure.
That is a second time, when one faggot crashes into an electric pole an keeps entire town without electricity.

[Anonymous No.1583645]

I usually buy arduino nanos from ali and they meet most of my needs or I just try to get around its limits like only a 10bit adc. I just saw that theres a blue pill which seems superior to the nano in every way almost. They both cost about 1.50 from ali.
Now from reading the blue pill doesnt come with a bootloader (not sure of the implication of this exactly) and it has the wrong resistor so the usb doesnt work without modding it. Does anyone have experience dealing with these two things? Should I start buying blue pills instead of nanos.

[Anonymous No.1583648]

>>1583645
pick up an ST-Link dongle, should be like $2. attach to SWD port, use open-source or vendor software to upload code to board. the F103 also has a ROM bootloader which you can use with any serial dongle on PA10/PA9 UART pins but I haven't tried this (see ST application note AN2606). ST offers STM32MXCude software to create startup code and set up pin allocations, but you could use lolduino if you really wanted to
>wrong resistor
some have the right one. some work regardless
>should I
yes

[Anonymous No.1583706]

>>1583546
LED will be always on, jfet drains battery all the time, even without signal.

[Anonymous No.1583707]

>>1583706
I drew a generic FET because MOSFETs are hard, OK?

[Anonymous No.1583745]

Anyone know what this thing is? I got it from a soviet reel to reel player. It has 2 solder lugs underneath.

[Anonymous No.1583746]

>>1583648
You could go further and turn one of the bluepills into a stlink by switching BOOT0/BOOT1 and loading it up with UART device you might have at hand, it could be any dev board with UART, an usb-ttl or even a fucking COM port of your PC.

[Anonymous No.1583749]

>>1583745
analog voltage meter

[Anonymous No.1583751]

>>1583749
Thanks due. Tho why would it be inside a reel to reel player where nobody will ever see it?

[Anonymous No.1583752]

>>1583751
Completely covered? The scale was not exposed?
That is weird.

[Anonymous No.1583766]

>>1582974
you are a girl ?

[Anonymous No.1583775]

>>1583707
>MOSFETs are hard
suggest simplified symbol

[Anonymous No.1583776]

Bought a bag of M0.9X2.5 PCB rivets, which I believe means 0.9mm OD and 2.5mm long. I'm using what I assume is standard thickness PCB, it's around 1.5-2mm thick. Anyone used these things before? Don't have any proper tool for it, so I'll try a centre punch and hammer I guess.

[Anonymous No.1583779]

>>1583766
The right question is: are you gay, if you jerked off to it thinking its a girl, later realizing its a guy?

[Anonymous No.1583782]

>>1581590
what do you call that blue work tray thing?
i feel as though I need one, or several

[Anonymous No.1583799]

>>1583779

[Anonymous No.1583815]

>>1583752
The scale was exposed. Why was it there I'm kinda wondering.

[Anonymous No.1583843]

>>1583815
volume indicator

[Anonymous No.1583849]

>>1583745
Looks like a simple tape recorder VU meter.

[Anonymous No.1583851]

>>1583782
DIYFIX S-170 480x318mm Silicone Pad Desk Work Mat Heat Insulation Maintenance Platform for BGA PCB Soldering Repair Tool

[Anonymous No.1583866]

I was thinking, I'm living with roommates and I don't want my amateuristic tinkering impact their lives. Is there any way to have a fuse like system in between so if I ever short something, it doesn't impact the main power?

[Anonymous No.1583868]

>>1583866
yeah, it's called a fuse. Or a circuit breaker. Also an RCD so you don't die

[Anonymous No.1583877]

>>1583866
You can get fuses and RCDs that you can just plug between your devices.

But you have to make sure they act quicker than the fuses and RCDs of your house.

[Anonymous No.1583906]

>>1583868
>>1583877
Thanks lads

[Anonymous No.1583916]

>>1583851
thanks anon

[Anonymous No.1583925]

>>1582900

BME 280 or 380. Its a bosch sensor. Wind sensors are called aneometers. You might be able to get away with using a calibrated differential pressure sensor though. PiW uses up too much juice unless you are going to keep it plugged in use an esp8266 or esp32 instead if you plan on going with a battery option.

[Anonymous No.1583933]

>>1583925
>aneometers
are typometers

[Anonymous No.1584028]

>>1583843
>volume indicator

nope, clipping indicator. if you're in the red then the recording is gonna be full of distortion. (however if you're Einstürzende Neubauten or similar, you want it to be in the red all the time)

[Anonymous No.1584048]

How dangerous is it to charge a 5s pack with a bench power supply if you don’t have any balancing?

Also is it just going to be CC/CV charge with the voltage multiplied by # of cells? So 1A-21V?

[Anonymous No.1584069]

>>1584048
Do power tool chargers balance?

[Anonymous No.1584077]

>>1584069
I posted this in the other thread- I think it depends on the brand.

Pic relted, the one on the left with the cells is a cheap brand 18V back and that has balancing in the pack. The middle board is from a Kobalt 24V pack and that seems to have balancing built into the pack. The two small boards on the right are from a 20V Bauer pack, and that one must have the balancing done at the charger and overprotection built into the tools. There are no chips on the bords, it has the wires and connections for the balancing, but then it has a bunch of extra connextions going to the charger compared to the 3 or 4 on other tools. The Bauer has 8 connections while most other tools onlt have a +, -, and temp sensor.

[Anonymous No.1584082]

hi /ohm/
so i want to control a second extruder on my 3d printer, my board only support 1 so i need a external PID temperature controller
i found pic related, my question is, can i replace the default thermistor by an other one (the one used in my extruder are different, much smaller)
thx !

[Anonymous No.1584083]

>>1584082
(the thermistor used in my extruder)

[Anonymous No.1584087]

>>1584077
thank you

[Anonymous No.1584095]

>>1583933
>>aneometers
>are typometers
anemometer - he was close

[Anonymous No.1584097]

>>1584028
>>volume indicator
>nope, clipping indicator.
commonly referred to as a VU meter (Volume Units)

[Anonymous No.1584101]

>>1584069
>Do power tool chargers balance?
'name brand' tools have balance boards in the battery pack.
they also have mosfet devices in the pack to open the circuit in the event of charging or discharging beyond factory preset current limits

[Anonymous No.1584113]

>>1584048
You can probably safely charge it to 5*4.1V or so, but then I'd go and charge each cell individually up to the 4.2V mark. They're matched so you might even be able to charge to full without balancing a few dozen times and only do balance correction occasionally, but I wouldn't bet on it. Trying to measure the difference between each cell after the first charge discharge cycle will tell you how careful you need to be about balancing. There are battery management boards for this purpose and they're not exactly expensive. The eBay/Ali search term being "5S BMS". The Amazon ones look a few times more expensive so I'd avoid those.

>>1584082
>>1584083
Probably not is my guess, thermistors aren't as universal as thermocouples. But if that thing will take a thermocouple, you could get a very small one to fit right next to the extruder.

[Anonymous No.1584114]

>>1583849
>>1584097
Seems legit.

[Anonymous No.1584239]

>>1584101
The Bauer tools aren’t complete piles of trash though. They must have overcurrent and over discharge protection inside of the tool, and then all of the balancing stuff in the charger. It has the wires for the balancing. Makes sense if they’re trying to sell their brand on affordable battery packs like Bauer and their $20 1.5Ah packs.

[Anonymous No.1584244]

>>1584113
I did a quick search on Amazon for the 5s balancing boards, around $10 with like 3 week shipping times from China.

Anyway will the batteries eventually balance themselves out? Like if batteries are connected in series and one is 4.2V and the other is 3.8V and you just let the pack sit for a couple hours, will they level themselves out at 4.0V?

I mostly want to do it to try it. But if I could collect some cells and assemble clean looking 2.0Ah Li-Ion cells for old Ni-Cd tools, it would be a hell of a lot better than 10 year old packs. I’m not about to pay $150 for two NiCd packs.

Then again Amazon has NiMH replacements for like $30, I’m just too lazy to order them.

[Anonymous No.1584249]

>>1584244
Get the same ones for $4 on ebay, but go for it. The batteries will not balance themselves out naturally without extra circuitry, and even if you have a BMS I don't think that will balance them just by sitting there, it's just when you charge them that it balances them. I believe as you discharge them if any one cell gets below the threshold, the BMS will stop any current from flowing completely.

NiMH are shit, don't go near them.

[Anonymous No.1584251]

Anyone know where I can torrent code composer studio? It wasn't on pirate bay.

[Anonymous No.1584253]

What are EE jobs like?
What should I expect?
btw, not sure if i'm asking in correct thread.

[Anonymous No.1584254]

>>1584048
>How dangerous is it to charge a 5s pack with a bench power supply if you don’t have any balancing?
Safe, as long as you check voltages on cells.

[Anonymous No.1584257]

>>1584249
Ahhh ok. I gotta figure out if I can even make them fit and look halfway decent before spending money on those boards. The Kobalt board could probably fit with 5 cells and that has balancing included, but it’s made for 6 cells and that will be harder to fit in the case plus I don’t want to destroy the tools with 25% more voltage over the 18V NiCD.

It would be so easy to drop in this Ironton pack, I could probably even fit 10 cells in there assuming the two balancing boards would fit, but the clips that hold the battery in the tool are in the way. It it were secured in the tool a different way, it would just slide in. That’s why I was thinking about doing 5 cells in like a pyramid base formation and then stick the board wherever, but this Ironton board is too large and the Kobalt board for the wrong voltage.

[Anonymous No.1584259]

>>1584254
Meh, that would be an issue because ideally i would like to seal it back up and try to make it look bone stock.

Pic related, I could so easily get the cells packed like this with a little grinding but would have to find a compact board or go unbalanced.

[Anonymous No.1584260]

>>1584259
Or be extra lazy, take the grinder to this and then electrical tape and hot glue the fuck out of it. But then I lose the clips that hold it into the tool.

[Anonymous No.1584261]

>>1584259
Then you'd need a BMS with balancing.
You can charge them with IMAX B6 of sort.

[Anonymous No.1584267]

>>1584261
Meh, I would almost rather keep an eye out for more clearance battery packs, maybe I can come across somebody getting rid of dead DeWalt or Milwaukee packs, salvage a couple cells, then steal the boards out of them.

I wonder if the HF Hercules or Earthquake brand packs are balanced through the charger like the Bauer packs. I think the 2.5Ah Hercules packs are only $25-$30. I’m going to scope them next time I’m at HF, because chances are if they only have 3 connections for the tool/charger, they have balancing in the pack. And then I’ll take a look at the shape and see what the board may be like, supposedly they’re almost replicas of DeWalt 20V packs.

Worst case scenario I wasted $30 for a handful of brand new 18650s, and everything Li-Ion I got from HF so far has had decent Samsung cells.

[Anonymous No.1584271]

>>1584082
thermocouples have a higher temperature range than thermistors, generally. if you're using anything but PLA you probably will want a temperature controller with a thermistor (type K are most common)

[Anonymous No.1584353]

If i have a 20v source and two devices, one connected directly to the 20v and other connected through a buck converter which drops 20v to 5V, is it safe to connect their ground together?

[Anonymous No.1584356]

>>1584353
you will anyway. buck converters do not isolate

[Anonymous No.1584358]

>>1584356
And what if each device uses separate power source? For example i have device which exposes 2 contacts you can short to activate it and i want to do it with a mosfet and an Arduino that is powered by a wall wart
Currently i am doing it with a relay because i am too scared to touch the grounds together

[Anonymous No.1584360]

>>1584358
buck converters establish a common ground between the input and output. it's not ground per se you have to worry about, it's whatever the device designer chose to put on the switch. if you don't know the device well enough to know if you can just pull one half of the switch to ground, use a relay or an optoisolator

[Anonymous No.1584396]

Where can I find reliable info on discharge profiles for both li-po and li-ion batteries, like, in comparison? Google gives me random stuff

Also, its time for a new thread, fags. Make one.

[Anonymous No.1584399]

>>1584396
the battery manufacturer
also slow your roll, we're only on page 4. wait until page 10

[Anonymous No.1584437]

>>1584396
>time for a new thread
Lol what kind of shithole board do you hail from?

[Anonymous No.1584438]

>>1584396
Oh and read the OP, there's a piece about Lithium Ions in there.

[Anonymous No.1584448]

>>1584438
It provides zero knowledge on the topic

[Anonymous No.1584466]

>>1584396
Li-po is a subset of Li-ion. What in particular are you comparing?

[Anonymous No.1584479]

If I take a 74hc541 and power it with 3.3 and the input signal is 5v, will the output be 3.3v or 5v-ish?

[Anonymous No.1584483]

>>1584466
I need to figure the one that has the best discharge curve for the 0.1C the load will pull. The point when voltage drops below 3.4 shoud be as right as possible, leaving only like 5% of charge or less. And I need to figure out if I need li-po or li-ion for my task.

[Anonymous No.1584549]

>>1584479
See for yourself how excess input voltage is clamped to Vcc and what that means in your case.

[Anonymous No.1584556]

Anyone any use at repairing flyback SMPSs?
I was asked to take a look at one.
Main FET had obvious burn marks on it so I replaced it.
Plugged it in and all 3 output rails came up.
Unplugged it and plugged it back in and it's dead again.
I'm pretty sure it's something on the primary side of the transformer as I'm getting nothing at all on the secondary side.
Everything up to rectification is okay too, I'm getting ~340V across the smoothing cap.

Gate of the FET seems to be getting a wave from the feedback optocouple, source is at 0V, drain is at 340.
There's an NPN BJT before the drain on the FET and I'm measuring 340V on all pins of it.

I've replaced the FET again today along with the BJT and optocouple but still not getting anything.
The primary of the transformer is getting the 330V but it's not switching on and off at all.

Anyone have any ideas what to look for?

Pic related.
U5 is the FET, Q1 the BJT.
Ignore the burn mark on the safety CAP, I shorted a live wire close by.

[Anonymous No.1584575]

>>1584556
>any ideas what to look for?
Yes, the circuit diagram.

[Anonymous No.1584577]

>>1584575
I wouldn't be asking if I could find the schematic.
Think it came from some chinky milling machine

[Anonymous No.1584587]

>>1583745
Lamp heat indicator

[Anonymous No.1584590]

>>1584479
>will the output be 3.3v or 5v-ish?

the only way it could be 5V was if the input signal was somehow directly routed from the input to the output, and that's not how digital chips work. instead, the input signals trigger some transistors which are powered from 3.3V and so can only put out 3.3V at most.

[Anonymous No.1584593]

If the water treatment plants add ferric chloride anyway, then is it really so bad to flush down your spent ferric chloride down the drain?

[Anonymous No.1584598]

On Aliexpress there are various ultra cheap yamaha sound chips (YM2612,YM2151,YM3812 etc). I don't know much about these kinds of chips, but why are there so many of them from chinese makers? Are they just really easy to manufacture? Are they very different from the authentic ones?

[Anonymous No.1584613]

Kind of unrelated but my body was charged up and my speakers started buzzing,
As soon as I touched a metal surface my body discharged and my speakers stopped buzzing at the same moment.
Coincidence?

[Anonymous No.1584627]

>>1584598
I'd guess fake or old stock (service repairs, unsold left-overs, factory rejects, etc.).

[Anonymous No.1584649]

Quick question, i have a stepper that i'd like to hook up to an A4988 driver. Is
2B -> A
2A -> C
1A -> B
1B -> D
The correct way to connect it, or do i have to switch B and D?

[Anonymous No.1584661]

>>1584649

20 seconds of trial and error.

[Anonymous No.1584663]

>>1584649
I doubt it matters, it will just set what direction counts as positive and what direction counts as negative in the software.

[Anonymous No.1584733]

[Anonymous No.1584735]

>>1584733
Did I ended up with too many vias?

[Anonymous No.1584738]

Is there any way to measure inductors? Are cheap LCR meters any good for that?

I want to check the big inductors of a crossover just for peace of mind. The crossover was overloaded in the past, and I've ordered all passives for replacement.

The inductors' plastic forms have melted a bit, but the shape of the winding itself looks intact and no burning of the magnet wire itself is evident.

[Anonymous No.1584758]

>>1584738
I have a cheap LCR meter and can't trust it for a larger inductance like a few henry. There are other methods to measure the L. What's the inductance range you want to check?

[Anonymous No.1584774]

>>1584735
Why so many vias? Looks like they could be avoided by mounting more components on thebottom of the PCB. Also is that KiCAD? If so, I'd like to know how you get parts to show up on the 3D viewer, instead of just their footprints.

[Anonymous No.1584776]

>>1584738
I'd personally make a relaxation oscillator with a large enough resistor such that the ESR of the inductor is insignificant. A 555 might not work too nicely, but a comparator-based oscillator should work well.

[Anonymous No.1584777]

>>1584774
you install the 3d models and you configure the KISYS3DMOD path to point to them
>not all footprints have matching models

[Anonymous No.1584834]

>>1584483
Li-po is a subset of Li-ion. It's a construction method, not chemistry, no difference on the voltage curve.

[Anonymous No.1584836]

>>1584735
show board not rendering

[Anonymous No.1584840]

If I have an hot air gun, is smd soldering still going to be painful. Soldering with an iron takes forever and requires a steady hand and patience which I dont have.

[Anonymous No.1584844]

>>1584840
hot air guns would work, but are much better at removing components than placing them. better get a toaster oven, preferably a convection type. add controller if desired (strictly speaking, it isn't, if you don't mind adjusting a knob for 6 minutes or so, but you will probably want a thermocouple thermometer to read the temperature as near the board as possible)

[Anonymous No.1584872]

>>1584834
Different electrolytes do have some impact on cell potential, you can see this on the wikipedia standard electrode potentials for metals being reduced either in aqueous solutions or in mercury. I'm no expert on how polymer electrolytes work but it's quite possible they have somewhat of an impact, at least on the discharge curve if nothing else.

[Anonymous No.1584899]

I made an ESP8266 fetch the time from the internet and display it on a 0.96'' oled through i2c. It works fine with my nodeMCU, but does not display anything on the screen when I switch to an esp-m3 (esp8285 based board). It still fetches the time and prints it to the serial monitor, and I have confirmed that power is getting to the oled, so I'm a bit lost as to why the screen is not turning on. Does it have something to do with the digital pins I am using? I really don't know much about i2c and how it could go wrong.

[Anonymous No.1584903]

>>1584899

[Anonymous No.1584907]

>>1584903
we all start somewhere

[Anonymous No.1584923]

>>1584872
Can you not find that out experimentally?

[Anonymous No.1584925]

>>1584923
Easily, and I bet there's documentation out there on Scopus at the very least, but personally I have nether type of cell just lying, nor do I have the ability to easily make a datalogging current/voltage monitor. Well actually I could make a current sink with a few of my MOSFETs or linear regulators, throw the cell from there to GND, and measure that Vcell with an ATMega or ATTiny ADC, but that would be like 2-3 hours of design and prototyping and I'm busy filling my stomach with egg fried vegetables on rice. With three sausages on top. It's a very filling meal, thanks to using 2 eggs. Though the veges are slightly overdone.<div class="like-perk-cnt">&#x1F346;</div>

[Anonymous No.1584934]

>try to solder
>the solder sticks to the iron and not the pad
>it bridges two pads
>it's also melting the breadboard
>pin snaps off
>everything's fucked
>100 more pads to solder
yeah fuck this

[Anonymous No.1584942]

>>1584934
Sounds like you need more flux, and to tin your parts before they're on the protoboard.

[Anonymous No.1584943]

>>1584934
>it's also melting the breadboard
What? Are you seriously soldering on a breadboard?

If so, the metal contacts are aluminium and can't be soldered like copper. A nice trick is to use olive oil as flux.

[Anonymous No.1584948]

>>1584943
I'm assuming by "breadboard" he didn't mean "solderless breadboard".

[Anonymous No.1584951]

>>1584948
A Veroboard? Never heard anyone call that a breadboard.

[Anonymous No.1584953]

>>1584951
Well I was thinking more manhattan style but with a piece of wood but anything goes.

[Anonymous No.1584962]

First suspect there would be the thin wires not making good contact with the breadboard. Second suspect would be needs lower pull-up resistance to Vcc >>1584903

[Anonymous No.1584976]

>>1584733
Is that a GPS module? shouldn't the antenna be facing outward?

[Anonymous No.1584978]

>>1584943
>metal contacts are aluminium
No longer nickel plated bronze?

[Anonymous No.1584981]

>>1584978
Maybe more expensive ones do.
All my breadboards are cheap chink shit.

[Anonymous No.1584982]

>>1584943
How the hell would someone solder onto a solderless breadboard with aluminium contacts?

[Anonymous No.1584985]

>>1584982
remove the tape at the bottom and solder on the contacts in the back

I've done that before for neater power supply to the board.

[Anonymous No.1584987]

>>1584985
You know that's a pretty bright idea.

[Anonymous No.1584997]

>>1584836

[Anonymous No.1584998]

>>1584976
The module is designed that way. It has a hole right next to the antenna connector, the only application for that hole I can see is to put the wire to the antenna through the hole, consequently putting the antenna right under the module.

[Anonymous No.1584999]

>>1584997
meh, that's about fair. you could probably eliminate a few by swapping some pins (e.g. SPI ~SS) around to fit your board better, and routing between .050" SOIC pads (go a little bit thinner on the trace if you like)
maybe, if you can, see about reallocating some pins in STM32MXCube to improve layoutability

[Anonymous No.1585013]

It finally arrived!
After getting chinked two times already if this fucker isn't a latching relay fucking AGAIN i am literally going to kill myself because i can't take this anymore

[Anonymous No.1585035]

>>1585013
Do you read the feedback before ordering?

[Anonymous No.1585071]

>>1585035
Literally useless because it is just a bunch of retards giving 5 starts when the package arrives without trying it and you cannot change the rating later

[Anonymous No.1585080]

>>1585013
YES IT FUCKING WORKS
The first two pins flip it one way and the other two pins flip it the other way and it stays that way forever
I am about to cry here.. after 3 months of ordering fucking useless relays i got ones that aren't a scam

[Anonymous No.1585082]

>>1585080
Congrats

[Anonymous No.1585154]

>>1585080
Which seller did you use?

[Anonymous No.1585205]

>>1585071
They they don't allow to stop sellers buying out bad reviews. But they should allow to put a worse review than you did before.

[Anonymous No.1585258]

>>1585080
gratz

[Anonymous No.1585303]

>>1584113
>>1584271
k thx for the tips, i finally found a arduino circuit to do that so i will try that

[Anonymous No.1585337]

>>1584934
>>the solder sticks to the iron and not the pad
Is this your first time soldering? Lead flows where it needs to when properly heated+fluxed

[Anonymous No.1585369]

>>1585303
To be honest I'd just get a PID that's compatible with a thermocouple, they're fairly common. In fact, the one you posted actually has a K-type thermocouple in the picture, albeit one meant for immersion. If you buy the right shape of K-type thermocouple for your purpose, it will undoubtedly be compatible with the one pictured in >>1584082, though you may have to crimp on a connector since you can't solder onto chromel and alumel.

[Anonymous No.1585437]

Is there any way to splice a 6 pin LEMO to a more usable platform?
I have a pair of SORDINs that I'd like to use with my phone for yard work and Baofeng for other work.

[Anonymous No.1585472]

>>1585080
cheers. there's a reason "caveat emptor" is by the alibay entry in the OP. you really do have to know what you're buying and avoid sellers that have no clue what they're selling. always demand pictures and part numbers, and check 'em

[Anonymous No.1585479]

Sorry for being so obnoxious and persistent, but I decided it would be better to make a PCB so I can get rid of these nasty effects from having everything wired and patched up on a perfboard, and thus I added some charge capability for the capacitors in the means of a LM2596 CC module, adjusted to 2A and 7.5V. For the sake of simplicity I'll ignore charging each cell individually.
I performed a test with a relay and everything was okay, so my question is,
Can I get rid of them and just use diodes to avoid unexpected feedbacks and shortcircuits on the welding circuit? It may be a very dumb question but I'm asking because maybe there are some things that I'm ignoring here.

[Anonymous No.1585539]

If i am connecting six illuminated 12v led push buttons to a 5v usb encoder controller, will i need a resistor? The button lights up fine on 5v but im retarded enough to not understand resistors.
link to the switch: https://www.banggood.com/-p-1195861.html?

[Anonymous No.1585541]

>>1585539
those accept the specified voltage applied directly to the lamp terminals for full brightness. the lamp circuits have resistors inside, selected for that voltage. feeding them with a lower voltage is 100% safe if they're bright enough for you

[Anonymous No.1585542]

>>1582049
First, don't trust that falstad thing, it's very unreliable when it comes to semiconductors. An hour learning LTSpice will save you many hours of fixing shit.
Zeners can blow up pretty quickly, and in my experience they tend to do it pretty much silently.
Yes, there will be current spikes in real life, and no, if they're happening thousands of times a second, that is not safe for your power supply.

>>1582053
the thing that's called beta in BJT world is called g_m for MOSFETs, more or less. I'd avoid calling it beta just because it can get confusing if you're dealing with feedback networks.

>>1584997
>KiCad
I'm new to /diy/ but can someone explain why people use KiCad? in my experience, Eagle is much more tolerable, especially since autodesk bought it.
Is there a reason to not have a ground plane?
Also, by the look of things, you'd be able to kill a lot of vias by putting that QFP on the bottom of the board.

[Anonymous No.1585543]

>>1585542
>why people use KiCad
It's free as in freedom

[Anonymous No.1585546]

>>1585543
>it's free as in what the FSF defines as freedom
I thought I was escaping /g/nu autism by coming here. Just use the best tool for the job that's available to you, jesus christ

[Anonymous No.1585547]

>>1585542
he's probably not turned on the new canvas that does transparency
>y tho
I don't trust SaaS as far as I can throw it and I prefer to withhold as much support as I can from that distribution model

[Anonymous No.1585550]

>>1585546
>escaping autism
>by coming to 4chan
neat

[Anonymous No.1585551]

>>1585547
>don't trust SaaS as far as I can throw it
eagle isn't SaaS you mongoloid

[Anonymous No.1585554]

>>1585541
Thanks!! :)

[Anonymous No.1585582]

>>1585541
no problem at all, thanks again.

[Anonymous No.1585589]

So, the difference between mosfet and a bjt is that mosfet only uses gate voltage to open itself but no current passes and a bjt actually lets current pass through the gate and then multiplies it by mixing it with the current from its second leg?

[Anonymous No.1585603]

>>1585589
Basically, yes. More precisely, a BJT's base current excites the current through the collector (or something along those lines) while a MOSFET's gate creates an electric field that changes the size of the depletion region in the semiconductor around it, and drastically changing its conductivity. The creation of this electric field means the gate acts as a capacitor of a sort, making it less desirable for some very high speed operations.

[Anonymous No.1585604]

>>1585546
Would argue that KiCad is a good tool as it has everything one needs. You even can export that 3d preview into something like Fusion 360 and build the case for your PCB before you even have it. That's some serious dedication for autism you mentioning.

I know there's better tools, but for those who do this as a hobby? So you don't pay monthly subscription for stuff you would use twice a year?

[Anonymous No.1585606]

>>1585604
Seconding this. I know I've never run into limitations in KiCad, at least ones not due to my own foolishness.

[Anonymous No.1585608]

>>1585603
i see. thanks
basically i want to trigger .1A current from an arduino logical pin, but what confuses me is how much current will the transistor draw from the logical pin at the base? is it all the current? do i need to use a resistor?
with mosfets this is super simple, i just wire the logical pin directly to the gate and boom done, i turn the mosfet on or of by setting the pin high or low
i would like a similar behavior with the bjt where if the logical pin is high, the bjt turns into a "short circuit" and when the pin is low, no current passes (while the current at the base is as small as possible since anything more than like 50ma will give my IC a prolapse)

[Anonymous No.1585609]

>>1585606
I like KiCAD except the library handling.
There's always some stupid problem I have to google when trying to import my own parts.

[Anonymous No.1585610]

>>1585609
In that regard, I had a much better time in KiCAD than in Altium and EAGLE.
The fact that in KiCAD schematic symbols are not directly tied to a footprint until you choose one saves you lots of headaches.
My critic is that shortcut behaviors are different in the PCB designer than in the Schematic designer.

>>1585589
More or less, yes. You can think in a MOSFET as a voltage-controlled resistor and in a BJT as a current-controlled current source.

[Anonymous No.1585612]

>>1585608
the reason why i'm not using fets for this is because i have a box full of bjts and mainly fets are huge compared to 3leg bjts and i was not able to find any cheap logic level bjt sized fets on ali

[Anonymous No.1585614]

>>1585610
> My critic is that shortcut behaviors are different in the PCB designer than in the Schematic designer.
Yeah, I guess that's because the tools were made by different people and they in their complete autism forgot to communicate.

[Anonymous No.1585620]

Bump limit's been reached, but I'll try my luck here first. Electronics illiterate basically, so this is kind of a SQTDDTOT.

I need to build an alarmed cabinet. I first off wanted to put reed switches on the doors and some sort of vibration sensor switch thing. Each of these sensor elements, I want to go back to some single point that will control and set off a ~100dB siren for maybe five minutes or so.

I've looked up some single reed switch diagrams which look easy enough, but what do I need to search for to find out how to do this single control source? Would it just be something like an electrical junction box?

[Anonymous No.1585621]

>>1585608
A BJT has a gain value; an hFE or beta, and this value determines the maximum ratio between the collector current an the base current. Usually it's at least 100, or it is in small signal transistors, but to be on the safe side I usually assume a beta of 50. You can get the low estimates of this from the transistor's datasheet in any case. Then say I'm running a 5V system, and want 0.1A collector current, that means I want 0.1/50 as my base current, or 2mA. Since the base-emitter junction is basically a diode to ground, I ignore the 0.7V drop since my math is pretty imprecise anyhow and say R = 5V/2mA = 2.5kΩ. Now 2mA is a fair bit to be sinking if you're in a medium-low power application, which is why I might tend towards a FET in this situation, but you could easily drop it below 1mA with the right transistor selection. But you want to ensure that you are operating in saturation else the transistor could get quite toasty.

[Anonymous No.1585625]

>>1585479
Quick check: 2S5P using 100F 2.7V capacitors --> total C 250F 5.4V --> total charge 1350 As --> charge current 2A --> charge time 675s or about 11 minutes. Really?

Why charging to 7.5V when 5.4V is the limit?
Doesn't series charging require some balancing?
What are D1 and D2 good for? D2 is shorted.

Just for reference: Image is from the kweld kit at
https://www.keenlab.de/index.php/portfolio-item/kweld/
Look at the >1000A bus bars. There's also a capacitor version at
https://www.keenlab.de/index.php/product/kweld-ultracapacitor-module/

[Anonymous No.1585634]

Cmon guys make a new thread

[Anonymous No.1585651]

>>1585634
>wants people to make a thread when we don't need a new one
>doesn't want to do it himself
well aren't you a bucket of unicorn shit

[Anonymous No.1585660]

>>1585620
Okay, I know where I've been going wrong. I've been looking for the right electronics jargon to search for, but I should've been looking for the security jargon. I've found some info after searching for "multi-zone" alarm circuits.

[Anonymous No.1585667]

>>1585620
I'd use a reflective optical (IR) sensor to tell if the doors are open. As far as vibration goes, wouldn't a nearby lorry or earthquake set off your alarm?

Anyhow, with a switch as a sensor you'd use a pullup resistor and have the reed switch itself pulling the alarm input line to 0V. If you're going to use a more complicated sensor (i.e. one that you can tune the sensitivity of like an accelerometer or reflective IR sensor) you should probably be using a microcontroller. The alarm itself could be as simple as a monostable circuit (perhaps with a 555 timer) and a buzzer.

>>1585660
Making the thing out of discrete electronic components is likely far cheaper than buying ready-made home-security industry parts. If you're willing to put in the effort to design a circuit, I'd go all the way and buy discrete parts, provided you can get them for a reasonable price and shipping time where you live.

[Anonymous No.1585684]

>>1585667
Well, the reason I was going to use these reed sensors is because it's more like a cage that I'm going to build. Long story short, I bought a rundown house with the intention of renovating it. Before I could do that, junkies broke in multiple times and stole my stuff that I was storing here because I just moved to the area. Now I've had to replace all my tools and things, I've moved into the place to stop them breaking in, but I've gotta go back to work because I'm now broke and have no money to fix the place up. So I was going to make a caged shelving unit out of angle iron, rebar, and things like that to store my tools and my computer in while I'm at work until I can better secure the property.

So it's not actually going to be enclosed, just designed similar to a cabinet. The vibration sensor I thought would be good for if they use an angle grinder, I assume you can get all different sensitivities. A single simple circuit with a reed switch will probably be the first thing, because the most likely way they'd try would be to just try to rip the door off (like they did with my shed...). Then I'll upgrade it over the next few weeks.

[Anonymous No.1585688]

>>1585684
Why didn't you hire a security company to do the alarm for you, again?

[Anonymous No.1585693]

>>1585688
Why is this /diy/ again?

[Anonymous No.1585694]

>>1585688
>Why didn't you hire a security company to do the alarm for you, again?
...With the piles of money I have just lying around?

[Anonymous No.1585696]

>>1585621
thanks for the great explanation.
i have one last question
let's say you have the 2ma on the pin which let's 0.1A through the transistor. So what if the power source is capable of delivering 0.5A? Will the bjt limit the current to 0.1A or let the 0.5A through? (with the 2ma at the base)

[Anonymous No.1585707]

>>1585604
>You even can export that 3d preview into something like Fusion 360
lo and behold, eagle does that too since it's an Autodesk product. I also have no idea what you're talking about with "monthly subscriptions." I don't know, I'm so used to having Mentor Graphics at work that when I come home and try to use Eagle, even it feels very primitive. KiCad's just as under-featured, but also extremely clunky with its hotkeys and shit.

[Anonymous No.1585767]

Interesting case of disinformation:
Why are PNP transistors referred to as "Normally On" Devices?
http://www.learningaboutelectronics.com/Articles/PNP-transistors-normally-on-devices.php

[Anonymous No.1585793]

>>1585696
Why not in between?

[Anonymous No.1585804]

>>1585612
should be able to find 2N7002s pretty easily which will pass a decent amount of drain current at 3.3V or above, Pic related. "logic level" is just an abbreviated claim about the transfer characteristics that the manufacturer is willing to guarantee. you can always look at a datasheet and decide whether the FET you have is going to typically be open enough at 3.3V or whatever logic levels you're using, and since you're not putting them on by the full reel, it shouldn't be a big problem to replace one that's a bit short of standard

>>1585660
you're looking for information on basic series/parallel switch networks, by the sound of it. much depends on whether your switches are normally open or normally closed tho

>>1585767
POO
IN
Q

>>1585634
we wait until page 10 you obnoxious refu/g/ee

[Anonymous No.1585849]

Do stupid electronics question go in ohm or stupid question thread?

Anyway, do FETs have a linear region like BJTs or are they only capable of being on / off?

[Anonymous No.1585855]

>>1585849
sure, and just like BJTs they have a safe operating area limited by several factors. older FETs are better for linear applications according to
https://www.infineon.com/dgdl/Infineon-ApplicationNote_Linear_Mode_Operation_Safe_Operation_Diagram_MOSFETs-AN-v01_00-EN.pdf?fileId=db3a30433e30e4bf013e3646e9381200

[Anonymous No.1585857]

>>1585849
They do. The problem with FETs are the names people give to the regions. USUALLY
>cut off = cut off = 0 Id
>LINEAR = OHMIC REGION = Usually where you want to keep it if you are using it as a switch
>Saturation = region AFTER the OHMIC region where increasing Vds WON'T increase Id = if your switch keeps too long here it'll heat up

[Anonymous No.1585859]

>>1585857

[Anonymous No.1585861]

>>1585859
Fug. I have brain damage, it's not a triangle, it's just a line from cut off to linear. Sorry

[Anonymous No.1585867]

>>1585857
for most loads, Vgs increases -> Id increases -> Vds decreases. "after" is a red herring at best

[Anonymous No.1585868]

Do you think this triangle wave generator circuit would work with a Schmitt-trigger inverter logic IC (CD4093) instead of a 555?
I'm going to breadboard it tomorrow, stay tuned.
(source: http://www.all-electric.com/schematic/eticircuits/555-triangle-with-independent-slopes.htm))

[Anonymous No.1585906]

>>1585868
It will, but the levels are poorly defined compared to the 555. If it must be CMOS I'd prefer the TLC555.

[Anonymous No.1585917]

Why is the number of images always so close to the number of posters

[Anonymous No.1585926]

Anyone has a surface graph of Ic(Vbe,Vce)? I'm trying to teach a guy some electronics and I think that would help him understand, instead of the classic two graphs of Ic x Vbe and Ic x Vce

[Anonymous No.1585956]

Can someone ID this chip?

[Anonymous No.1585958]

>>1585956
oops

[Anonymous No.1585977]

>>1585696
The maximum collector current is limited by the base current. In this case, the transistor would be acting in the linear mode, because to limit the current it would have to have a significant collector-emitter voltage.

>>1585958
Context?

[Anonymous No.1585981]

>>1585977
It's on the main board in a USB camera/car DVR

https://www.aliexpress.com/item/USB-Port-DVR-Camera-For-Android-4-2-4-4-Car-DVD-Radio-Player-Q8/32757600815.html

[Anonymous No.1586054]

>>1585981
I can only assume it's an MCU or dedicated video IC, probably the latter. Why do you want to know? Looks like it would be a nightmare to try and tinker with, lest you have a hot air station or reflow oven.

[Anonymous No.1586063]

>>1585625
Yeah, sorry for the leftovers of making the welding the terminals connected to the source of the MOSFET rather than its drain. I realized that was a stupid idea and changed it before making this schematic.
>charge time 675s or about 11 minutes. Really?
Each welding discharge only consumes less than one hundred joules, therefore a timeout of a couple seconds to charge that amount is okay with me. I can be patient to wait for the thing to charge until it reaches 5.4V when I start using it. Besides I don't have a power supply or a DC converter that can pump so much current.
>Why charging to 7.5V when 5.4V is the limit?
The voltage dropout on the diodes is about 1V each, but as one of them is shorted -and I'll remove it-, I'll only make it supply with 6.4V. For the moment I'm sticking to one of these chink LM2596 DC step down converter modules with current limiting capabilities.
>Doesn't series charging require some balancing?
I got 3 more LM2596 modules, so I can, at least in theory, use another one to fix each cell's voltage exactly at 2.7V. It's a very cumbersome method and would take quite some space on the PCB but it's worth a try.
>What are D1 and D2 good for? D2 is shorted.
D1 is to avoid the caps to supply power to the rest of the circuit when the 12V I'm supplying it with is gone. I agree, I should take off D2, is a leftover.
>Image is from the kweld kit
I've explored it a bit and I'm a bit puzzled on how does it do this power adjustment thing, how does it calibrate the system to output a set amount of joules modifying variables such as the pulse width, knowing that the full resistance of the system is unknown. Its schematic isn't at hand either.

[Anonymous No.1586071]

>>1584251
its free.....
just go download it from TI

[Anonymous No.1586078]

>>1585958
It's hard. It may be a MCU, a LCD controller or a camera controller, and these are hard to ID as it's often of some obscure Asian brands.

[Anonymous No.1586116]

>>1585625
>>1586063
Never mind, found the schematics.

[Anonymous No.1586117]

[Anonymous No.1586143]

>>1585767
More weirdness:
https://www.allaboutcircuits.com/textbook/semiconductors/chpt-4/bipolar-junction-transistors-bjt/

[Anonymous No.1586149]

Why the fuck does the N mosfet only work if your blow your load into the drain?
If you place it before the load then it doesn't work at all, how is that possible?

[Anonymous No.1586153]

>>1586149
see these red arrow? that's your substrate connection
see both red parts? between those is your channel
see the dot that isn't there but should be, tying the substrate to the source? that's why everyone cares about Vgs and not Vgd

[Anonymous No.1586157]

>>1586143
>electron flow
get the fuck out of here with that

>>1586153
Not him but that's a nice way to look at it. I've been looking at the semiconductor geometry of JFETs and MOSFETs a bit lately and I see diagrams of MOSFETs with no particular difference between the D and S. Actually searching for images with the substrate connection give me ones that do show such a bias, which solves a little mystery in my mind, and clarifies the nature of the MOSFET in general.

[Anonymous No.1586160]

>>1586157
So as a continuation from this topic, images of JFETs are often like this, with a gate connection on both sides. I find it a bit odd that we force the same polarity of electric charge on both sides of the D-S junction, since wouldn't that mean that in the very middle of the junction there will be an area with exactly the same electric field as without any charge on the gate? Wouldn't this make the device impossible to get into a completely insulating condition? Or is the "near enough" case good enough for basically all purposes?

[Anonymous No.1586161]

>>1586157
>Not him but that's a nice way to look at it. I've been looking at the semiconductor geometry of JFETs and MOSFETs a bit lately and I see diagrams of MOSFETs with no particular difference between the D and S.
Yeah with power mosfets and discrete parts we forget they can be 4 terminal devices, and are by essence bi-directional.

[Anonymous No.1586162]

>>1586161
Would 4-terminal MOSFETs make it easier to make things like those perfect diodes, or bidirectional switches / SSRs, or more JFET-style analog circuits?

[Anonymous No.1586165]

>>1586153
So the voltage going into the drain must be lower than the voltage going into the gate, so the difference between gate V and drain V is at minimum the saturation voltage for the fet gate?
that makes sense now

[Anonymous No.1586166]

>>1586162
it sure would

[Anonymous No.1586167]

zero knowledge about electronics here but can do basic soldering.. one of my power supply power mosfet was fried as seen on pic and 4 of them are the same brand (UTC GBT10N50ADG)

is it possible if could replace the broken one with different brand of mosfet but kinda similar specs? (FQPF10N50CF)

[Anonymous No.1586169]

>>1586167
>is it possible if could replace the broken one with different brand of mosfet but kinda similar specs
Yes, but you'd have to be pretty sure about those specs. AFAIK, the main things to match or improve are V_DS(max), V_GS(threshold), Q_G, R_DS(on), and I guess whatever thermal characteristics too.

[Anonymous No.1586170]

>>1586167
>>1586169
Oh and pinout of course.

[Anonymous No.1586174]

>>1586162
it wouldn't help much for power stuff, since the gate-to-channel voltage must still be limited to protect the oxide layer, and the substrate would need to be reverse-biased vs. any part of the channel (this is the intrinsic "body diode" people keep talking about)

>>1586165
drain voltage doesn't matter for the purposes of turning off and on, just the difference between gate and substrate (usually tied to source)

>>1586167
sounds like you know a little more than zero about electronics
they look basically identical to me. success is likely

[Anonymous No.1586175]

>>1586162
Well, that's how analog switches and SSRs are made

[Anonymous No.1586177]

>>1586149
The gate needs to be several volts higher than the source for the FET to conduct. If you connect the load between source and ground, once the FET starts to conduct current, the voltage drop across the load pushes the source voltage above ground, reducing Vgs.

If the FET saturates, then the source voltage will be approximately equal to the drain voltage, so in order for the gate voltage to be substantially above the source voltage, it must also be substantially above the drain voltage (which if the load is in the source, is usually the positive rail).

So if you want a "high side" switch (above the load), you need to be able to drive the gate with a voltage above the positive rail. This is why high-side drivers exist (and often include a voltage doubler to generate the necessary gate voltage).

[Anonymous No.1586181]

>>1586174
What about a circuit with diodes from both the S and D to the substrate such that whichever has a lower potential is connected? Don't know if it would be useful, but in my mind it feels like it would make sense.

[Anonymous No.1586183]

>>1586181
in parallel with the substrate-to-channel junction? looks redundant

[Anonymous No.1586216]

>>1586177
Does that mean that the fet protects against a short circuit? Say you have a short across the load so the load no more drops any voltage and the fet source and fet gate voltages become the same and the fet stops conducting?

[Anonymous No.1586217]

Isn't that convenient

[Anonymous No.1586243]

>>1586216
>voltages become the same
No, quite the opposite. If you keep the gate voltage and lower the source voltage by shorting the (low-side) load, the gate to source voltage increases and so does the conductance of the transistor.

[Anonymous No.1586256]

>>1586217
Is it a JFET?

[Anonymous No.1586261]

>>1586256
Yes, 2N5484/5/6.

[Anonymous No.1586264]

>>1586261
Yeah, I'm not really sure why JFETs have pins called "drain" and "source" if they're identical, perhaps call the gate the anode and the other two pins the cathodes, or vice versa if it's the opposite polarity JFET. Also presumably you'd be able to craft tetrodes or pentodes as JFETs with two or three gates, I wonder if anyone has done so? Or would putting 2 or 3 JFETs in series have the same effect?

[Anonymous No.1586267]

what is the easiest way to make pcbs at home?

[Anonymous No.1586270]

>>1586267
toner transfer + etching (sponge or Seno)

[Anonymous No.1586273]

>>1586264
Dual gate mosfets were used for preamps or mixers e.g. in FM tuners. Cascoding 2 jfets has the same effect.

[Anonymous No.1586357]

What's a good 8 bit bidirectional shift register DIP? I haven't found any

[Anonymous No.1586370]

How come my drill works after first getting hot, then smoking and shortly after it sounded like it shorted.

I'm guessing the smoke is from the "insulation" of the windings.

[Anonymous No.1586392]

>>1586264
they are interchangeable because the gate is physically located halfway between the source and drain on that device. on JFETs not so built, the end closest to the gate would be called out as the source