/diy/ - Do It Yourself

>>1102621

> when the leaded solder fumes hit you

>>1102624
Fumes never used to bother me, but it gives me blinding migraines nowadays. I had to build a fume extractor, but I still feel like shit afterwards

>>1102624
Lead boils at 1750*C. It's not in solder fumes. ROHS is to protect the environment from the billions of electronic devices humans discard every year not electronics hobbyists.

>>1102631
Have you switched to lead-free solder recently? Different fumes.

>>1102637
>ROHS is to protect the environment from the billions of electronic devices humans discard every year not electronics hobbyists.
too bad it creates more waste because lead-free solder is shit

>>1102631
>>1102624
Pretty sure the fumes are from the flux and whatever else is on your iron/board/wire when you melt the solder. Shitty flux-free solder is actually quite nice to have for when you only want to reflow. And I'm pretty sure the fumes from when you spill the brush cleaner are waaay worse for you.

>>1102637
Yeah, I cynically expect the lead-free stuff to have nastier fumes, versus the shit that's been used for decades.

If AC alternates than why is one lead the "hot lead"?

>>1102709
Someone correct me if im wrong, but the hot wire is always the one delivering the current. The current isnt going back and forth, its just switching polarity. The neutral is just to complete a circuit.

Sorry if this is too spoonfeedy, but i cant find any info on this particular thing online.

I have a schematic for a small amp driven by an lm386, at roughly a half watt.

Thats not a lot of power, all things considered. Ill still go through with it because i like tinkering, but ive been readong data sheets and ive came across the tda7391, a 35w bridge amplifier for car stereos. I like this because it can be ran off 12v or 9v, which this project is based around.

Now, the question. Most of the pinout i can adapt, except the in+ in-. One of those would be ground in my original circuit. Can i combine ground from one on the input pins, the ground pin on the 7391, and the ground from my original circuit? Or would i need to isolate my original circuit from the 7391?

Also, the 386 appears to have the option of a gain stage that is incorporated into the original circuit, would i need to create another gain stage before the 7391 to properly drive it? If so should I just use the 386, or would an opamp be better?

If the 386 could be used to feed the 7391, should i just use original circuit as is, then add the 7391 afterwards.

Pic related is typical usage for the tda7391 from the datasheet. Ill post how the 386 is used in the circuit next.

>>1102713
This is typical usage of the lm386 with gain from the data sheet, exactly as its used in the circuit im trying to modify.

>>1102713
Why not just try it and see what you get. These parts are not expensive so i guess you can afford to mess around with them. Use both in different setups, try stuff and see what you get. Mostly, you will get experience followed by knowledge which is enough to make the price of those ICs worth it.

>>1102710
>The current isnt going back and forth, its just switching polarity. The neutral is just to complete a circuit.
You are wrong, think about the following:
If there isnt going current back and forth, why is there a wire needed to complete the circuit then?

>>1102727
I have to order them, if i realize i need something i have to order that too. It takes a minimum of 4 days for it to get to me. Im just trying to get a full list of stuff i might need to keep ordering to a minimum.

>>1102621
I thought her whole boob was out.

>>1102709

because the neutral lead is very close to earth potential (0V) at all times, ideally. the voltage at neutral should be no more than your IR conductor losses, so is very unlikely to shock you if you touch it. but the "hot" lead will give you a buzz for sure.

>>1102709
Because the other is tied to ground.

That's just how it's done; it doesn't have to be that way. E.g. 240V in the US has two hots and no neutral, 3-phase has either 3 hots and a neutral (wye) or 3 hots and no neutral (delta).

>>1102709

so you have one that is 0v always

and the other one relative to the first one goes from -120v to +120v (if you are america)

>>1102715

anybody noticed LM386 is quite popular on amps?

>>1103669

presumably coz punters look at the datasheet and see they can get 0.7W out of it at 9V. what they fail to notice is that this comes with 10% distortion. if you wanna a reasonable 0.2% distortion, you're limited to 1/8W.

the makers of the LM386 used a brilliantly-evil strategy of inflating the actual output power coz dumb audio guys cant into datasheets. no honest manufacturer would ever rate their power output at 10% distortion. they'd show the 0.1% or 0.2% THD power ratings.

>>1102621
MFW seeing this https://www.youtube.com/watch?v......

>buy 2x8 lcd display
>hook up everything to a nano, pinouts and everything setup to either the datasheet or adafruits generic lcd wiring guide
>contrast is non-existent and never displays properly

i found some post online where a guy recommended to hook up a negative voltage line to the contrast pin (3) on the LCD screen. i put it in the LCD/arduino circuit, and put -4.5v on the contrast pin, and now lo and behold the contrast works, increasing the negative voltage (from -4 to -1) supplied lowers the contrast, and lowering it (-4 to -5) increases it

did i fuck something obvious up? i was hoping to use this LCD with just a standard 5/10/20k pot like i've done with 2x16s before, but i can't get this thing to display properly with them for the life of me. when P3 is hooked up to the wiper between GND/5v, the text on the screen is barely visible, and the changing the pot doesn't do anything at all, and i've tried different pots too, same effect

>>1102734
not the anon you we're replying to, but this actually just blew my fucking mind

Hi /ohm/.
I'm new to electronics and am gonna be playing with an arduino. But I don't have any resistors. Looking at ebay and the likes it doesn't make sense to buy anything outside of bulk of 100 or so.
So since resistors resistance is additive when seriesd I'm thinking it'd make sense to buy a large quantity of one kind right?
But what type should I get to fit my fucking about? I don't really know what I will be doing aside from playing with a few LED's and some sensors. I don't know what resistors I'd want for the leds even. I can't really search myself to an answer except that I could figure out what my specific leds would need.

>>1104751
Tl;dr
If you were going to be stranded on an uninhabited island what resistor would you bring?

>>1104751

Why choose?
https://www.amazon.com/Joe-Knows-Electronics-Value-Resistor/dp/B003UC4FSS

>>1102713

Anon, I can't figure out what in the fuck you are trying to ask.

I am going to assume "original circuit" is referring to the lm386 circuit you linked. All those ground pins should have the same, common ground or you are going to run into floating nodes and get some wonky ass voltages across your circuit.

Your 7391 datasheet should tell you what is required to drive it, try digging into it a bit more. Also the lm386 is an opamp.

I haven't looked at the tda7391, but I'm pretty sure it's got its own internal amp, really you should look at what the input voltages should be and decide from there if you need a pre-amp based on whatever the hell it is you're going to be feeding it.

I am trying to find "pancake" type stepper motors on eBay, does anyone know what my search terms should be, like "nema something..."?

>>1104861
thin?

>>1102621
Grinman

>>1104752
1k i think. Or maybe 2.2k. Although i like 10k too.
I'll go with 10k because whatever device you may use will need to source the smallest current and last the longest

How come 5v is used for so many things? It seems too nice of a number. Is it because of the way volts are defined? I understand 3,3v because its a pretty random number

>>1102621
Im soon going to build a mitx pc in a mitx case and im thinking of making my own modular PSU.

Nothing fancy, just cut and strip the wire of the 4 pin Molex and make them shorter so I dont have a ton of cables i wont need in my case, but still wants to be able to plug it in if I need the power.

Anyone here have done anything like that?

>>1104908
>How come 5v is used for so many things?
Standard from TTL days. I'd guess it has to do with the voltage the transistors work best with
>I understand 3,3v because its a pretty random number
Again just guessing, newer smaller and lower power transistors can work with lower voltages

>>1104979
I believe the "measurement" got better or whats it called.
ie at what voltage a 0 becomes 1 and 1 becomes zero.

You can make a transistor that switches at anything between hundreds of volts to millivolts, it just depends on what application you need it for. Around the 1-6V mark is good for easily converting battery supplies into and has a low spark risk and therefore low need for insulation. There is equally no good reason why mains voltage is 120-240, or why they're at 50-60 Hz; it was proposed in the design stage and stuck.

>>1104908
5V was the standard for 74-series TTL.

You need enough voltage for several junction drops at 0.65V each, plus some headroom. The 5V figure was probably a trade-off between speed, cost and power consumption (i.e. a higher voltage would have increased cost and/or power consumption without much of an increase in speed).

Unlike 4000-series CMOS, which can run from anything between 3V and 15V with higher voltage reducing propagation delay but increasing power consumption, TTL requires the voltage be fixed at design time.

Designing CMOS parts to operate at 5V simplifies interfacing with TTL parts. Modern CMOS devices run adequately fast even at low voltages, and the increasing number of transistors on a chip (over a billion for a typical Intel CPU) make minimising power consumption a priority (hence modern CPUs using barely over a volt).

sup /ohm/, I am trying to find a type of SMPS I remember seeing on youtube/forums at some point.

the side story is I'm building a TIG welding machine and need a isolated supply for the gate driver. for the sake of simplicity and not having shit hanging off zip ties waiting to cause a fire(literally none of the chinese psu's have mounting holes). i'm looking for an all in one supply that provides multiple outputs(3.3v for mcu and UI, 12v for gate driver, 12v blower fan at 150W), 1 and 2 can obviously share grounds but the gate driver cannot as it's switching a 400VDC mains rail.

now the psu i'm thinking of looked just like your standard industrial SMPS but each output was it's own self contained module, only sharing the input filter and DC bus, it could then provide any configuration of voltages with them all being completely isolated from one another.

>>1105289
Ok well like voltage isn't exactly arbitrary, you need moderately high voltage for transmission around your house otherwise there is too much loss from resistive heating. But not too high or else insulation becomes a problem and the voltage isn't useful. In the olden days us of a used ~100v because it was convenient for bulb manufacturers making the filament that length and resistance and yada yada yada.

Same with frequency, long distance transmission required ac for high voltage distribution to overcome resistive losses. But why 50/60hz well if its to high frequency then the transmission line ends up acting as an antenna and you get skin losses and all kinds of rf black magic bullshit. Go ask Maxwell if your so interested. But if the frequency was too low the transformers would have to be huge as fuck and also you would see the light flickering.
People in the t past might have been stupid but they weren't retarded.
5v logic is kind of similar, what voltage do we need to operate all the transistors and shit while also not having too much of a drop when fanning out to all the other logic gates and shit. I.e. What voltage can we get away with so people don't need buffers in-between every component. Well in the old days silicon was expensive so this kind of shit mattered. Nowadays with fab getting as small as it is its just as easy to bang on as much shit in the silicon as you want, if your only connecting a couple of soc's together that you bought from fucking adafruit or whatever in order to wrap leds around some gaudy bullshit that you made to tweet whenever you take a shit it doesn't matter about voltages so much because it doesn't have to go very far.

>>1105560
I wasn't implying that they were both completely arbitrary, but rather that both examples were as arbitrary as each other. I think with today's technology we could pull off 500-2000V mains at 100-1000Hz, at the expense of a few more third-world electrocution deaths.

>>1103669
>>1103681
It really became popular back when audio chips were new and expensive. These days its used as more of a right of passage or one off project than anything serious.

When I built mine I had no idea about circuit layout and component placement so it doubled as a layout and parasitics lesson.

This video really helped me https://www.youtube.com/watch?v=lBGE5lwbruE built it, learn from it and then move onto newer and better IC's.

>>1104751
Just buy a cheap resistor kit like this https://www.amazon.co.uk/PIXNOR-Resistors-Assorted-1120pcs-1ohm-10Mohm/dp/B01441YDJY/

For less than 10gbp, 12usd its trivial.

>>1105774
>>1104755
Yeah I did this.
I didn't realise they existed but then I did a bit of searching and I got packs for ceramic capacitors, resistors and electrolytic capacitors.

Should probably have ordered some transistors too.

do I need a special crimping tool to use this kind of conector or any plier will do?

>>1106397
i prefer using vise grips if i dont have the tool handy, but just buy the tool its like 5 bucks and usually has a wire clipper, multi gauge strippers, and different sized crimp points for small medium and large crimps. its 3 tools in 1 and its actually not crap.

>>1106397
I had two huge eye connectors that I needed for 2 gauge wire to make a spot-welder, so I drilled a few holes in a block of scrap timber with a fat bolt on either side, so that when I put it in the bench vice the two bolts squeeze the connector and make a permanent connection. Hasn't failed since. Though the spot welder doesn't weld shit.

>>1105754
Ehhhhh 2kV in your wall sounds pretty retarded. You know how many diyers get whacked with 120 ever fucking day got swapping fans and outlets? 95% of them would be dead if we had 2kV mains.

You need a crimp tool if you don't want the wire to fall out. Comes with some wire strippers or as a separate tool. Thomas and Betts make the most popular version, but it's fuckin' expensive. I recommend the Klein strippers. But all you need is the part of the tools between the blue handle and the pivot labeled "Insulated/ non insulated"

>>1102640
That is exactly true. Also,
>1000s exceptions because Pb-free solder is shit

>>1104908
Also, and this might be a coincidence, zener diodes designed to run at about 5V have very low temperature coefficient.

>>1106903
>>1102640
That may be true, but at least the waste won't have lead leeching back into the environment

>>1106948
>back into the environment

where it came from...

hey /ohm/

I'm trying to make a USB HID game controller.

I have some basic electronics components (buttons I'd like to use, breadboards, wiring, good soldering iron, resistors, etc)

I also have a
TI MSP430 LaunchPad
TI Stellaris LaunchPad

Having a bit of trouble trying to figure out where to start.

Which micro should I be using? Any general advice for working with TI launchpads or for this project in general would be appreciated.

>>1107069
don't start with TI LaunchPad's, they are TRASH. literally the hardest dev environment to setup, and lets say you're an expert, it will probably just not work anyway due to the alignment of the moon or some shit(buggy as hell).

most of the stm32 boards can do USB HID with middleware ST provide for free, ofc it's ARM so it's a pain in the ass to setup but it's a lot more achievable in an afternoon. just decide early on if you want to do standard HAL or try out cmsis(the first is easier for small projects, the latter is batterys included but much more complicated).

senpai

https://www.youtube.com/watch?v=41r3kKm_FME

Why do we have two threads going?

>>1107573

other one didn't link to the new thread in the last thread

kind of a shame because that was a very old chain (it helps a lot if you are looking at the archives)

>>1106816
I live with 240VAC, I find a good rule of thumb is to turn the power before putting a fork in a socket!

>>1106816
also both switching and linear supplies would be fucked. switching semiconductors need voltage rating margins and commercial igbts only do 1.2kv. igbts suck and kv fets are only just getting good. it might just be market pressure but there's no good cheap switches past 600v (265vrms plus margin). meanwhile linear transformers would need 8-16x as many turns.

my understanding is mains frequencies can't be increased a lot either because of line inductance.

What digital microscope should I get?
It'd be fun to have stupid high magnification but those get expensive if they're to have the magnification range I need (I don't know how low I need to go. Just something to make SMD a bit easier to inspect).

I'd prefer something cheap over something proper.

>>1107952

for a PCB just go on ebay get one of the 15 dollar USB ones

>>1107689
>IGBTs suck
Why? Please educate me.

>>1108001
the current tail limits them to lower switching frequencies if you care at all about efficiency

>try to submit this post
>error you are banned
>for a frogpost
>on /tv/
REEEEEE

I'm thinking of getting a used oscilloscope. Is it worthwhile to get an analog one, or should I just save and get a new digital scope?

There's a Tektronix 2213A in good shape on Craigslist that I'm looking at

Posted this in the last thread but I'll repost in case any Radio peeps are around.
So /ohm/, I'm trying to build a basic AM modulator, but for time codes, not for radio.

I have a source that outputs 3.3V when high, and a 3.3Vpp 1kHz AC carrier wave.

When the source is high, it needs to be 3.3Vpp 1kHz wave, and when it's low it needs to be a 1.15Vpp 1kHz wave.

I've tried toggling a drain BJT and using an inverter, and I get the voltage reduction but it cuts off the bottom of the wave. Would a voltage divider work when just a resistor doesn't?

I've tried googling around, but all I can find relies on an AC input from a mic to a transformer, but I have a DC input.

Is there an easier way to do this than going from my D.C. Output to act then into another set of transformer coils in phase with the first set?

any tips on stripping small ass 26+ gauge wires? Was trying to repair my girlfriend's lightning charger but I kept tearing off the wiring in the teal and white lines. Red and black stripped easily but I am pretty sure they were a bigger gauge.

PS: Yes, I am very new to this.

>>1108294
you could try burning the insulation off as long as it's not silicone.

>>1108299
Like take a lighter to it until the tubing is gone?

>>1108294
I've got a Hakko wire stripper that goes down to 30 gauge. Was like $5 dollars on Amazon

>>1108311
This? I have a hakko but it's not gauge. And my hands are too shaky to handle it but if it's the pic related one, I might get it.

>>1108312
I believe so

How do I reverse water level sensor output from (lower voltage indicate lower level) to (lower voltage indicate higher level)?

>>1107556
Love what the guy made, but why did he have to be a brony fag

If i regulate a 18vdc source to 9v will this double my mAh? Ignoring the power dissipated by the regulating circuit, that is. Why or why not?

>>1108483
> If i regulate a 18vdc source to 9v will this double my mAh?
If you use a linear regulator, no. If you use a switching regulator, you'll get double the battery's mAh rating.

Linear regulators conserve current, switching regulators conserve power (so if you step down, current out is greater than current in).

>>1108400

I don't think he's totally gone like a lot of bronies are

I remember Dave Jones made videos that exposed his autistic train fetish but I still like him

And recently we learned that Big Clive was on 4chan, so...

Is 300°f too hot for the face of a 100 watt led cob? Even with a running CPU heatsink the face of the chip can climb to over 300 degrees and with it off it will climb to over 500 degrees actually start burning the insulation on my thermocouple. The backing and heatsink However stay cool to the touch with the fan running and only get slightly warm with it off.

>>1109375

read the datasheet

>>1109387
theyre from china so they have no datasheet

how hard would it be to modify an atx psu to output a higher voltage on one (or all) of the rails? i know every power supply is different but is there a generalized guide or something to give a general idea?

>>1109711
try a search for:
adjust atx power supply voltage

There are plenty of instruction online.

trying to fix my flourescent lamp wtf am i doing wrong? this is how i wired all up only top tube lights up and if i swap the tubes around same thing happens, i tried replacing the bottom starter but didnt help

>>1109775
I'll look again but most "variable voltage" tutorials are either using linear regulators, buck and/or boost modules, or just having 3.3/5/12/-12/-5 all have their own hook-ups on whatever case they make. None of these are what I am looking to do, I want to actually modify the output of the supply itself.

>>1109850
you maybe need a ballast in there somewhere?

>>1109873

I'm not interested in looking it up again but I read several pages about it a few weeks ago.
They all described how to locate the 'feedback' / sense circuit and change it to adjust the output.
Some made it keep a constant output that was different than the OEM setting.
Some added a variable pot to have an adjustable output for a bench supply.

>>1109480

read a datasheet of a similar product

>>1109888
the ballast in connected before this circuit

>>1109897
Changing the output voltage is the easy part. The hard part is doing so without the PSU failing as a result. I.e. you need to determine the behaviour of the modified circuit and ensure that it doesn't result in any ratings (voltage, current, power) being exceeded.

Assume that any safety features in the original design (e.g. current limiting) will be ineffective if the output voltage is modified, as the relationships between output current, input current, power dissipation of various components, etc are likely to change if the output voltage changes.

E.g. an output current limit could normally be relied on to ensure that input current and power dissipation are within bounds. But changing the output voltage could allow you to exceed all of those before exceeding the output current limit.

If you're going to nigger-rig a PSU, never use it unattended.

from the other /diy/ post,
hey again, electronics addict here, glad to answer any questions.

I have a Acceleration Module GY6500 and use it for a proto. What the fastest way to communicate data with arduino, I2C or SPI?

>>1110745
Ever made anything useful or impressive?

>>1106975
Yeah that's correct.

Just like Uranium ;).

>>1110745
well I have made quite a lot actually, to name a few:

-a Pcie 1x board
-an RF signal processor
-a board with an ARM a9 that can run embedded linux
-a generic 80x80mm "core" board with an fpga,micro and much more
-1gb/s generic optic link board for rs422 multi channel communications

i'm signed on an NDA on most of these, but ask any questions and I will try my best to answer them.

>>1110755
well I have made quite a lot actually, to name a few:

-a Pcie 1x board
-an RF signal processor
-a board with an ARM a9 that can run embedded linux
-a generic 80x80mm "core" board with an fpga,micro and much more
-1gb/s generic optic link board for rs422 multi channel communications

i'm signed on an NDA on most of these, but ask any questions and I will try my best to answer them.

>>1110803
I live in middle of europe. Is it worthwhile to study analog ic design? Im a really good student but I worry about work.

>>1110804
>Is it worthwhile to study analog ic design
Yes because you will fill your knowlegde box. I have been workin on training period 6 month and used 2/3 digital skill vs 1/3 analog skill

>>1110804
ic design is a hard business, mostly kept for hardcore professionals.
if you will find yourself working in IC design, it will be mostly Verification/QA for quite a long time (5 years at least.)

I suggest you check if your uni teaches embedded design, you will most certainly find a lot of work there, especially now in the era of iot.

ok guys I posted over in another /ohm/ thread not realizing it was essentially dead
>>1110388
update to this post I made, on the serial connector there was a barrel plug for external power, and my dumb ass grabbed wall wart, and only noticed the mA being 500 and ignored the volts (it was 12, while card reader took 5)

after plugging it in, it powered up (green status light turns on) I left for a second to grab a card to test swipe, and I come back and the reader is giving off a smell, it was hot to the touch, and I immediately unplugged it. I looked up the power specs (which I should've done earlier) and realized it uses barrel usb power, so I wired up a barrel to usb to see if I can still save it, (+ on the outer, - on the inner) no green light,

So I did
>pic related
I hear something running on the board, but the led status lights do not turn on. Sorry for shitting soldering, my hands were shakey after drinking some mountain dew, and playing overwatch :/

Does anyone know where I can look up
>int0
>xtol1

online? I googled
>int0
and it mentions its for interrupt which makes sense, but idk if int0 on this board uses the same purpose.

...edit.. I think the status lights are burned out..

anyways any help is appreciated.

>>1110896

that looks like an ISP header

https://en.wikipedia.org/wiki/In-system_programming

You might have damaged a chip on the board, hard to tell

>>1110808
They have one or two PIC/AVR courses though I learn AVRs at home already (no ARM sadly, my friend told me no one cares about AVRs anymore because of ARM, dunno if its true). Quite a lot of HDL/FPGA courses though. I'm in second year of my bachelors microelectronics course so apart from analog IC design and some semiconductor, component manufacture and material science stuff these things are all my subjects focus on.

>>1110905
I examined the other side of the board, and around some solder points, it looks like some sort of a liquid, but I cant wipe it off, around some solder points there is white stuff, almost like ashes burned into the board.

>pic related

>>1110905
I examined the other side of the board, and around some solder points, it looks like some sort of a liquid, but I cant wipe it off, around some solder points there is white stuff, almost like ashes burned into the board.

>pic related

>>1110923
that's flux. it doesn't matter for 99% of circuits.

i have a faulty chinese pickit where one of the chip resistors had a broken solder joint (and then later became one with the carpet and got replaced by an axial). check to see if there's any bad joints on your board.

>>1110804
Maybe you could start by checking how much you'd need to travel to find companies doing analog IC design. Then consider whether you're ok with that.

Personally, finding such job would most likely mean leaving the country.

>>1110937
Well there is ON Semiconductor design center right in my hometown and it cooperates quite tightly with my faculty (one designer of theirs even lectures design here), so the chances of getting employed there are decent-ish, but other than that, I don't think there is anything else.

Ayyyyyyyyy

I think she's fucked.

>>1110896
Measure the voltage at the solder points on the board while plugged into the USB supply.
If something shorted while on 12v it 'could' be pulling the 5v down due to current limiting of the supply.

Guys I'm a complete beginner and I feel so proud right now.

>>1110975
now make a motor controller to turn the pot for you

>>1110977
I can get my arduino to do that. Just connect potentiometer middle into arduino output, or what?

>>1110977
Is there an electronics project chart like pic related?

I think there should be.... but Im a noob

>>1110981
ROLLAN

>>1110982
>>1110981

don't bring that cancer to /diy/...

s m h

>>1110979
you can control the led directly with the arduino, but you can't really control it by interfacing the arduino through the pot.

>>1110981
Yes. See >>1105546
Also, like >>1110984 said: don't use this thread for rolling.

>>1110984
>>1110991
Thanks senpai.

post deleted.

>>1110987
How?

>>1110981
rolling.

>>1110999
the arduino can turn an output pin connected to the led on and off rapidly. the percentage of time the pin is driving the led is the apparent brightness, because the switching gets averaged out by your eyes.

>>1111003
That is so ghetto

>>1111004
all the best electronics tricks fall under that category. that technique is called PWM and is hardwired into the microcontroller in the arduino.

https://www.arduino.cc/en/Tutorial/PWM

>>1111005
OK but don't all electric appliances "work" 50/60 times a second?

>>1102621
What's a good soldering station for a electronics beginner?

t. canadian

>>1111006
the mains voltage gets filtered by your computer power supply or wall plug, so the 5 volts your arduino gets are almost entirely dc and whatever 60hz ripple is left is probably immeasurable.

>>1111008
post leaf

>>1111006
No, they don't, but even if they did; clock speed and duty cycle are different.

50% brightness is just 50% 'on' for whatever the frequency is, be that 50Hz or 50000Hz.

>>1111009
no leaf but this was tuesday

>>1111009
Does it do that via capacitors?
>>1111010
So how do CPUs measure time so as to stay consistent in this?

>>1111012
>Does it do that via capacitors?
Bridge rectifier + filter caps + some other shit
>So how do CPUs measure time so as to stay consistent in this?
crystal oscilators

This is very basic stuff. The links in the OP will explain better than I can here.

Look up bridge rectifier on youtube, then look up crystal oscillators.

>>1111014
Oh ok thanks - something more difficult, then:
If I were to make a DIY (32-100ohm) headphone DAC, what type of capacitor would you recommend and why?

>>1111011
close enough. i have a weller WLC100 which is widely recommended and works, but in retrospect i'd appreciate a temp readout.

>>1111012
other guy answered your question but as a fun fact, old appliances used to measure time off the mains. you still could do so easily if you wanted to but it's not extremely accurate.

>>1111011
>this was tuesday
I live ~350 miles from the Gulf of Mexco
This morning was -11C
Global Warming My Ass

>>1111021
Thanks mate!

>>1111028
be sure to get some brass wool. the sponge that comes with it is fine but it's sort of a nuclear option whereas you usually just want to get crap off the tip.

How do i get this thing to run 2 tubes?

>>1111038

what is that

what kind of tubes

>>1111038
thats a magnetic ballast that was used in a fixture to run 2 T8 15W fluorescent tubes but the switch for it broke down and now im trying to repair it

>>1111042
>>1111040
quoted myself..

Currently battling power supply derived noise in this obscenely complex Japanese amplifier.

>-70 dBV noise floor
>Drops by 15 dBV if you filter out low frequencies
>Noise waveform in sync with mains

It's currently fully restored and performing well within specifications (i.e, better than new on every account), but I think it's dumb to settle for "good enough" when your noise is literally 50 Hz hum. Wish me luck.

>>1111038
>0,01uF
What is that made of?

>>1111051
Do I need a multimeter for a diy DAC/amp?

>>1111054
no idea dude this is what was in the fixture im trying to repair

>>1111055
you need an oscilloscope really, but that's probably too complicated for you unless you want to piece it together from breakout boards.

>>1111059
I've a hobby kit with schematics for a USB device but I want to learn about part replaceability.
Like, what capacitors would you recommend?

>>1111038
measure resistance on windings
report results

>>1111065
both 28 ohms

>>1111051
>broken tablet of creative accomplishment
story time?

>>1111040
>>1111054

other request made
>>1109856
>>1109850

>>1111062
high quality electrolytics are typical (eg, ones specifically marketed for audio). other capacitor technologies often don't have adequate energy density for the capacitances needed for audio.

i'm not a big audio guy but i'd suspect any "audio caps" on ebay are guaranteed trash. if you want good caps try digikey.

>>1111076
I see, but would you pick, for instance, e-caps or polypropylene, or whatever?

>>1111055
If something goes wrong. You should learn how to use a meter either way.

>>1111073
The first time I used it, was while repairing a set of Creative computer speakers. Since its only purpose is to be a camera remote control (which is art), I could not resist the double entrendé.

>>1111079
poly caps fall under the category of film capacitors which are distinct from electrolytics. pic related are electrolytic caps, which you want.

>>1111069

>>1111082
Why do I want an electrolytic capacitor and is bigger better?

>>1111083
so the blue that comes out of the transformer and the bacl i attack accordingly that that scheme? and then whats marked "N" i pull to "N" BEFORE the ballast? if thats how you meant then how come the original wiring didnt have that wiring?

>>1111084
see the prior post. electrolytics have much higher capacitances per unit volume compared to film or ceramic caps, so they're bigger.

they're actually kind of shit though which is why better specced audio electrolytics sell.

>>1111088
So why not get a big poly cap vs a small e-cap?

>>1111090
a poly cap with the same large capacitance as an equivalent electrolytic will be two orders of magnitude larger and more expensive.

>>1111093
Ohh... so how do I tell a scam e-cap from a proper audio e-cap?

Quick question that I don't want to devote a whole thread to. I have a trashcan running on 6 AA batteries in series, can I just connect a 9V power supply to the battery terminals?

How many mA should my power supply be? More importantly, how can I determine how many mA I need for future such projects?

>>1111085
The N doesn't go to the ballast. It goes to the other end of the tubes.
The L goes through a switch to one blue and one black.
>>1111085
>how come the original wiring didnt have that wiring?
So far you haven't shown the original wiring. I don't know exactly what it was.
I gave you my opinion and went through this several times in the other thread.
Separate ballast wire for each tube or only one will come on.
The schematic I've offered does that. If you don't want to try that, wait for someone who knows more about it than I know to come along and tell you the proper way to do it.

>>1111095
buy it from digikey, mouser, or some other authorized distributor. i'm sure you could find genuine caps on ebay though if you looked hard enough.

bear in mind you don't strictly need audio caps. they're just specced to be less lossy.

>>1111069
>both 28 ohms
You didn't say 28 ohms between which color and what color.
That's why I drew the schematic as I did.
If it's blue-blue 28 ohms and black-black 28 ohms then I stick with my schematic.
If it's blue to black 28 ohms and blue-black 28 ohms the tie the two black to L and the blue to one tube each.

>>1111103
Like this

>>1111025
Weather =/= climate
Take your ignorance back to /pol/.

>>1111129
/diy/ is a /pol/ client thread

>>1111110
that schematic shows line going thorugh the ballast and thorught tubes and starters and out to Neutral before the ballast? but i have 2 wires going into the ballast as you can see on the picture. do i simply just disconnect the blue and use it as the neutral ?

>>1111129
but when a weather event like a hurricane happens it's suddenly OMG! CLIMATE CHANGE CAUSED THIS!!!

>>1111135
I'm in the USA
to me black is L
white is N
green is Gnd (earth)

I don't know what color your country uses for each one but the schematic is labeled with N and L
Just wire it like the schematic.
The electricity has to go from the L (hot wire)
to the N (neutral / not hot wire)
to do any work.
It performs it's 'work' by going through something on the way.
L>ballast>tube cathode~~tube cathode>N
the start circuit is:
L>ballast>tube filament>starter>tibe filament>N
(if the lamp is started the starter is an open circuit)

>>1111051
>TFW noise is due to the transformer magnetically coupling to something

I powered the amplifier on with external power supplies, and the noise went away. However, merely connecting the power transformer without allowing it to power any part of the amplifier, brings a 50 Hz noise to the output. FML.

>>1111149
did this and one didnt strike and the other one went insanley bright and i cut the power after 1 sec cause it was making sounds and sounded like it would explode

>>1111149
>>1111159
and then i tried but still sounded like it would explode and one didint strike, so i actually dont know what you mean

>>1111160
>so i actually dont know what you mean
I still didn't see where you told me the wiring for the ballast only'
28 ohms between ? and ?

>>1111162
blue-blue
black-black

>>1111165

>>1111167
will try this one

>>1111169
>will try this one
electrically, it's the same as >>1111083

blue and black on one end go to L
blue and black on other end go to tubes
other end of tubes goes to N

>>1111160
>still sounded like it would explode
Are you operating this on the voltage specified for the lamp originally?

>>1111157
Oh lol, found the issue. This ultra high-end amplifier (think $ 3000 class when new) has the SUPER LONG AND SKINNY ground wire for the input signal as well as the speaker outputs going literally a quarter turn around the transformer, on the underside of the case.

What the fuck. Moving them literally cuts 15 dBV of noise. GG Luxman. 0/10 Japanese pedantry.

Is this good enough to reflow small smd parts. And in general as a hot air gun.
http://www.ebay.com/itm/220W-LCD-Electronic-Heat-Hot-Air-Gun-Desoldering-Soldering-Station-Nozzle-/162195752894?hash=item25c39ec7be:g:D6oAAOSwFV9Xz7iI

>>1111194
LIKE THE MOMENT WHEN THE BRAKES LOCK
AND YOU SLIDE TOWARD THE BIG TRUCK
(Crashing noises)

You have to disassemble the entire FP assembly in order to access anything that's not the power amplifier. Bleh.

Im a bit confused about this, what exactly is V and I without subscript? does it mean instantaneous voltage and current? Is it correct that V = Vm/2 and I = Im/2?

>>1111450
V, I = Vm, Im
they just got lazy

>>1111458
but then what happened with the 1/2?

>>1111097

asking again please.

>>1111645
>I have a trashcan running on 6 AA batteries in series, can I just connect a 9V power supply to the battery terminals?

As long as there aren't batteries in it, yes.

>>1111645
>How many mA should my power supply be?
Look on the device and see how many mA it draws.
Your supply should provide that much or more.

>>1111645
>how can I determine how many mA I need for future such projects?
The same way. Look at the power requirements of the device.

If the power consumption isn't listed, connect an Ampere meter in series with a power supply or battery of the correct voltage and operate the device in it's normal manner.
Use a supply that provides the same or more mA than the device uses in operation.

Is it just me, or has anyone noticed there is far less free shipped stuff on aliexpress?
I created a cart a month ago before 2017 with 40$ worth of random electronics components, now I've checked again and many of the items in my cart now have a shipment fee, increasing the cost to around 70$, with shipping fees reaching 14$ in some cases.

I hope this isn't permanent, I liked the site. Maybe I should try ebay.

>>1111460
Trigonometric identity

>>1111270
...and to lend some closure to this, here's how it performed after the modification.

In short, pretty gud. All 50 Hz noise is gone and performance is generally ~3x better than the original specifications. Yay.

>>1111677
Any problem with using a higher mAh power supply, is there any danger for over-sizing it? (Provided it says 9V DC output)

>>1111681

I too have noticed this

>>1102621
I have a question about a project I'm working on.
I need to heat something up to 700°C using mains power (240V). What kind of resistance will I need to do that? How can I calculate the temp in °C?

>>1111894
You can try this:
http://www.jacobs-online.biz/nichrome/NichromeCalc.html

The thing is that you need quite a lot of resistance wire to run it directly from the mains. Use a transformer if you want smaller element. Also, even if your heating element is at 700°C, your work piece or whatever isn't. How close to it you can get depends on the heat losses and how long it takes depends on that and thermal mass.

can you 3d print pcb yet

Is it possible to use an attiny85 to both regulate a lipo boost circuit (4.2v -> 5v) and measure the voltage from the battery?

An anon made this schematic for a dummy blinking alarm light for the car, that only blinks when the key is out of ignition.

Question is, what wattage should the resistor be? And should I just get a mini pcb to put the resistor on or can I solder it inline with the wire as long as its in a safe housing?

>>1112065

Assuming standard 12v car system, with 25/15 fuseboard connections.

>>1111874
>Any problem with using a higher mAh power supply,

If the device specifies a fixed voltage and you supply that voltage it will draw the mA required if they are available.
Any extra capacity in mA will not be noticed by the device.

Some devices (LEDs for instance) require current limiting - constant current instead of constant voltage.
The item you mentioned is a constant voltage (9V) device.
It may require no, some, or all of the mA listed depending on the state it's in.
It will always expect 9 volts to be there.

>>1112065
>what wattage should the resistor be?
>Assuming standard 12v car system

A 12.6v car system usually has >14v when the car is running (needs higher voltage to charge the battery)
When the ignition is first turned off the battery voltage drops to ~13.8v almost immediately.
After sitting a while, the battery voltage falls closer to the 12.6v level.

The voltage drop across the diode is ~2v so the resistor is dropping the difference between the battery voltage and the LED drop.
To be safe I'd still use 12v across the resistor for calculating.

12v/470Ω=26mA
26mAx12v=.306W
almost 1/3watt

Using a 680Ω resistor drops the wattage to .21 watts allowing for a 1/4w axial lead carbon resistor to be spliced into one of the wires and covered with heat-shrink.

>>1108312
Not him but I got that exact wire stripper and it is fucking amazing, I didn't feel like paying $60aud to get a set of klein, but I think these things will last a long time anyway.

>>1112123
>File: dcp23.gif

I probably should have attached this pic instead.
It has the ways to calculate for watts on it.

This is a 400w 120v heating element from a fog machine.
1. What is the white circular thing on top?
2. Can I pump air through this safely?

>>1112255
>What is the white circular thing on top?

It's a safety device to disconnect the electrical supply if an over-temp condition is sensed.

Thermal switch. thermal breaker - sometimes called a Klixon because that company makes a LOT of them.

If there is a button on the other side you have to press the button to reset it.
If there is no button it either self-resets when the temp gets to the safe temperature or it is not resetable.

>>1112255
>Can I pump air through this safely?

If you didn't know what the 'white thing' was, you probably can't do much of anything with it 'safely'

This thread is cancer. All this information can easily be googled in 5 seconds.

What are the most ubiquitous circuits in your area of interest in electronics? I've been painting some schematic-inspired bullshit and I need more ideas.

What do you /ohm/ think of circuitmaker (altium) ? . I am a young electro engineer. I need a free tool to design circuit. I have been trying kicad but the interface fuck me up now.

>>1112263
Oh so its sort of like a simplified thermostat. And im going to be running hot air through it regardless, just wanted some insight.

>>1112462
might as well just pirate altium senpai

>>1102621
I'm laying 240q al feed for machine, what are your thoughs on putting up an i/o cabinet and feed it from the machine?

>>1112491
>like a simplified thermostat
Yes. It's just a factory preset thermostat.
They are usually wired to the control circuit and only carry a small current.
The controller senses the change in the status of the thermal switch and takes whatever action it's programmed to do.
Some are wired to directly control the supply current.

There are many types but the most common are NC > OPEN when temp is reached and NO > CLOSE when the temp is reached.

Yours is probably a LIMIT which opens to shut down the heater.

>>1112555
Awesome, thank you for the help. A built in failsafe system, ill still need to use a temp sensor to measure the air being blown from it.

With a little googling I found out that these heaters run around 440℉, and I plan to use brass or copper tubing coming out of it. I know brass is an alloy and usually contains some lead, could running this hot air through it cause leaching? Would copper cause leaching? If so my backup plan would be to coat the inside of the tubing with something heat resistant and food safe, teflon maybe

>>1112606
leaching of lead from the brass is the least of the things to worry about with this

>>1112614
How so?

I wanna do something like this (https://www.youtube.com/watch?v=90yM1BceT_8)) but are arduino cameras good for the job? If not, what are good small cameras for this type of work?

>>1112615
>How so?

You said you were blowing air through it.
If you aren't breathing the air directly or using it to bubble water you intend to drink, the microscopic amount of lead that could leach (perhaps none) can't be as dangerous as fiddling around with exposed heaters, blowers, and electrical wires.

Maybe more appropriate on /g/, but I just got done installing the mobo and PSU on my new build.
Waiting to buy a CPU (prolly an i5 6600K) and a GPU (idek, been a nvidia fanboy, but AMD Vega looks SIIICK).

>>1112725
Cable management. Could use a little bit of work, but I'm not unhappy with it as is.

>>1112727
Without the side panel in the way.

>>1112728
sexy

>>1112725
Case is a Pandora ATX by Bitfenix (which has an undeserved bad reputation for some reason. Sure, the side panels are a little flimsy, but that's a non-issue if you're not retarded. Sure, the radiator mount is a little weak, but I'm air cooling.) Also, who can pass up that programmable display on the front of the case?

Mobo is an Asrock z170 Pro4. Got it cheap. Open box on Newegg, had to jump on it.

PSU is a Seasonic G-series 550 watt.

>>1112733
Thank you very much.

how do I find the spec for this? http://www.allelectronics.com/item/mts-12pc/dpdt-on-off-on-mini-toggle-switch-pc-terminals/1.html
I feel like a DPDT is straight forward but it's hard to tell if it's behaving correctly....

>>1112753
Also worried I might have fried it with a 3V battery connection. Pin 2 works as expected but pin 4, 5, and 6 don't.

>>1112753
>it's hard to tell if it's behaving correctly....

That's what continuity testers are for.

>>1112757
ffffffffffffffine. Also, considering it's 120-250VAC can a 3V current be passed through it?

>>1112758
3VDC*

>>1112758
>>1112763

It's a switch
It connects two wire together
If 3v will go through the wire - it will go through this switch

>>1112765
the handle moves back and forth
the bar at the bottom connects terminals
it's not rocket science

>>1112765
All right. I did a continuity check and it's entirely dead on 4, 5, and 6. So I am not sure if it's something special about the switch or it's bad. I will keep looking for specs on it. I found a chart of various types of DP switches but without knowing what mine falls under doesn't help. Thanks for the feedback though.

>>1112767
>without knowing what mine falls under doesn't help

it falls under >>1112765
that one

RATED: 6 Amp @ 125 Vac, 2 Amp 250 Vac
ON-OFF-ON
connections for each state are shown >>1112765
there

pic related goes with >>1112766

>>1112769
so it looks like there is something wrong with the switch then.

>>1112771
show a diagram or better yet, a pic of what you are doing

>>1112774
refer to
>>1112765's left most diagram
If I connect a power source to the middle pins on either side, only the left side will actually allow power to flow to the load from its respective pin. The right pin is dead. I have an RGB LED for the load but am only connecting to ground and the blue pin to test the switch. It lights up on one side but not the other. Even trying moving the switch to different positions.

>>1112776

>show a diagram

>>1112767

>>1112497
I am going freelance, plus I had some trouble saving my work a while ago after craking it.

>>1112785
Still complex to me

>>1112883
What are you trying to do?

>>1112889
Reproduce a small version of ariane 5. Just a weekend hobby

>>1112766
>it's not rocket science
>>1112890
>a small version of ariane 5.

apparently, it is

where does the switch go?

How do I manufacture my own transistors from silicone ore?

>>1112937
>silicone ore

You mean... rocks?

anyone read Electrical Engineering: Principles and Applications by Hambley? is it worth it? I want to start messing around with more High Voltage stuff

First of all, excuse my ignorance and my limited English skills.

I created this thread >>1112415

The problem is that I have some hissing coming out from my audio port

I believe my GPU is inducing current into the op-amp IC mounted directly under it on the mobo.

However, it could also be that the isolation Gigabyte claims to have created on the mobo is just a lie and that even the Creative DAC outputs noise and the op-amp is just amplifying it.

The reason I believe the former is that I've managed to change the hissing's characteristics by putting load on the GPU and making it consume more power

the GPU is the Gigabyte G.1 Windforce X3 GTX 970

That's the background, here's what I want to accomplish: I want to build a super-cheap op-amp audio amplifier that I can fit inside an Altoids tin/coffee can. I have an aux output that comes from a non-amped port, that port is 100% quiet and I can't hear anything on it with my Shure SRH440s, what as I read, are quite sensitive (aka require very little power to drive)

The link that was given to me last thread to that blog also spoke of that O2 amplifier that the writer designed to be good, diy-er friendly, etc, but it's still a fairly complicated project for me, mostly because I don't want to make a PCB or be forced to get some fancy case, I just want something I can spend minimally (5-10$ max) on that uses very commonly available parts that I can walk down the street to get. This is meant to be disposable if it turns out I have to get an external DAC to kill the hissing.

The OP-Amp I've decided on is the NE5532, what I need from the good people of this thread is a schematic that won't burn out my expensive headphones and that introduces absolutely NO noise into itself, I only need it to have 3 ports, one for power, one for aux input and the other is where I plug my headphone, volume control would also be nice. (I can control the volume from my pc even if I have an amp, right?)

(cont 1/2)

>>1113028
(cont 2/2)

The specs of the headphones are:

Transducer Type Dynamic, Neodymium magnet
Driver Size 40 mm
Frequency Range 10 - 22,000 Hz
Sensitivity (@ 1 kHz) 105 dB/mW
Impedance (@ 1 kHz) 44 Ohms
Maximum Input Power 500 mW

>>1112898
>>1112890
>>1112883
He's not me. I was the one initially asking about the switch.

of the books in the OP, which has the most practical projects which you can build as you learn? I feel that the best way to cement my knowledge is to put it into practice as soon as possible

>>1113029
i know jack shit about audio but http://sound.whsites.net/ could have something for you

So this is probably a dumb question but, what are your guys feelings on things like the Radioshack Learning Labs?

I acquired 2 of them for free (one just the board, one complete in the box with the components)

I DO plan to learn some basic circuit design in the future after I graduate and have off time.
Im guessing I would be better off just using an emulator in the computer?

>>1113161
Also I have a Heathkit ET-3100 board.

Is this one worth keeping or not?

Im trying to get all my old shit out of my parents house right now.
Ill throw them on ebay if they arent worth having around. Theyve been sitting around for almost a decade now.

>>1113162

it's worth money, whether or not you want to keep it is up to you

I get what AC is, but I can't wrap my head around residential AC wiring. Why 3 wires? What's the difference between hot, neutral, and ground? Even in a 2 wire setup, why are both wires not considered hot?

How accessible is IC design to the homegamer? Companies like OSH Park can do turnaround PCBs for $5 each in small quantities. Does a similar service exist for ICs?

There was a group called HomeCMOS but the page hasn't been updated in 5 years so that's pretty much bust.

>>1113266

ground = the literal ground
hot = sin wave between +-120v
neutral = 0v relative to hot

>>1113277
So neutral is a DC voltage hopefully near ground, ground is a DC voltage AT ground, and hot is an AC voltage relative to neutral?

>>1113280

yes

>>1113272
You can get on MOSIS project wafers but it's pretty darn spendy, at least $10K I believe.

>>1113272
My VLSI professor had the chips we designed for our final manufactured. I could ask him where he gets them done at.

>>1113280

Not quite.

Ground is, obviously, the reference (and, literally, electrically connected to a pole in the ground). It's 0V, and the reference for everything else. It's not AC or DC. It's not supposed to carry current during normal operation.

Neutral is the center tap of the service transformer (the big one attached to the pole near your house). As a center tap, it provides a halfway point between the ends of the transformer. It's then bonded to ground at the main service panel (and ONLY the main service panel). Barring fault conditions, this ensures it is at the same potential as ground. The key difference is that neutral is meant to be a current-carrying conductor, while the earth is only there to help prevent any equipment casing or anything connected to it from becoming live in a fault. This is why they are bonded only at the main service; if they were bonded elsewhere and a fault occurred just right, everything attached to ground could potentially become energized.

Live/hot is what's actually connected to one of the business ends of the transformer. It's at 120V (in the US, anyway) relative to the neutral and ground. Because neutral is only the center tap, the two lives that the ends of the transformer provide are each 120V relative to neutral, but on opposite phases. That is to say, when one end is at +120V, the other is at -120V.(It's actually just under +/-170V at peak, as 120V is the average voltage, or root mean square/RMS of the AC waveform, not the maximum.) So, if you have an appliance that needs 240VAC to work, you connect it to the two hots instead of the hot/neutral.

That's how you end up with three (it's really 4) lines from a "single phase" system.

>>1113316
There are other similar services and at least couple of years ago, the smallest chips made on the oldest processes were "only" 2-3k.

How hardy and reliable are bench power supplies?

Im tempted to buy one of the thousands of old used HP bench power supplies on ebay.

Are they something that can be worn out and not work correctly?
Or are they something they works until it doesnt?

Also what about the fact that most of them do 2amps or less. Is that going to limit someone?

>>1113266
The reason that one wire is considered "hot" (live) and the other neutral is that neutral is connected to ground. So you'll get a shock if you touch the hot wire but not if you touch the neutral.

For a US 240V supply, both wires are hot.

>>1113449
What's the 3rd wire for?

I want to talk to my car's engine with my microcontroller through the OBD-II interface. I drew up pic related to convert the interface my car uses to microcontroller language.

Microcontroller is PSoC 5LP, logic level is 5V, will it work? Does it have any chance of frying my microcontroller or the car?

>>1102624
THAT LACK OF FEEL

>>1113576
you have to really fuck up big time to destroy a car electrically, be more worried about sending it some data encoded wrongly and accidentally erasing everything.
you don't have a better transistor laying around instead of using two? nothing wrong with it i guess.

>>1102621
Hey, where can I buy soldering kits/toys?

Like in HS we had a catalogue to choose a project from to work on.

I built a bitching DC power supply, and a AC strobe light that I still have, and use to this very day

>>1113673
ebay, banggood, aliexpress

How is this kind of circuit called?

>>1113708
that's just a bunch of parallel LEDs showing the effect their parasitic parallel resistance has on the brightness. there's not really a name for it i guess other than the obvious. please do the needful and give us more context.

>>1113710
I was wondering how to make one of these LED "level" meters often found on music equipment. That's what I came up with. As I ramp the voltage up (with the slider on the right) the LEDs turn on. I imagine it has a name. Notice the resistances have different values.

>>1113715
do you want it controlled by a potentiometer or voltage feedback or by a microcontroller?

you can wire a pot as a rheostat and use it as the series resistor but the brightness control won't be very linear and you'll need a second series resistor to prevent excessive current at the low ohm side of the wiper

if you have a feedback voltage to control brightness you can buffer it (and bias it) with an opamp and have that amp drive a LED through a resistor but again this won't be linear brightness control

with a microcontroller you just want PWM

>>1113715
>how to make one of these LED "level" meters often found on music equipment.
Those are usually done (when not done with a processor, that is) with ICs specifically designed to drive a bar graph display based on input level. Internally they have a bunch of comparators.
One such IC is LM3914 (www.ti.com/lit/ds/symlink/lm3914.pdf).

>>1113715
> I was wondering how to make one of these LED "level" meters often found on music equipment.
Not passively. Viable options include:
- a comparator per LED
- an ADC and some logic
- a comparator, a DAC and some logic.
- a microcontroller
- a dedicated "LED level meter" chip

Also: VU meters use a logarithmic scale.

>>1113353
VT?

>>1113708
what software is this?

Took apart my old xbox cos i was bored. How likely is it that the capacitors are still holding charge? hasnt been used in >3yrs

>>1113787
falstad circuit simulator. perfect for new enthusiasts

>>1113146
make:electronics by platt

Hello, I want to make a LED driver for 64 x 2.0v-3.8v@350mA each, in series OR parallel.

My wall voltage is 220v-240v AC.

I think I need a power supply to get it running at DC 220v@350mA OR 3.5v@22A . Anyone got a schematic or pointer?

>>1113789

zero chance. after a few days, all the caps will have self-discharged.

>>1113939
>at DC 220v@350mA OR 3.5v@22A

these 2 choices, at the extremities, are very bad. one presents dangerous voltages, the other requires very thick cables. what you want is to create a series/parallel combo using a bunch of these middle-ground units, where neither the currents or the voltages are crazy high.

I'm a newbie and trying to get my head around the concept of a bypass capacitor. If I understand it correctly, at a high enough frequency the current switches so fast that a negligible ammount of charge builds up in the capacitor, meaning that the current essentially does not decrease (because it switches too fast for it to do that)
am i on the right track?

I'm picking out parts for a buck converter which makes 5v/500mA from a 12v battery
My calculated Ipeak is 1 A, the only inductors that i can find which aren't fuckhuge are all rated for 0,9-0,7 A
Am i gonna be safe with those or should i look for bigger coils ?

>>1114030
most inductor ratings you see are for rms current ie dissipation. what you care about for peaks is saturation current which is often a looser limit. what sort of inductance do you need? if it's a really large value you should increase the switching frequency. if you're not driving your switch through a wet napkin you can do 100khz.

>>1114029
that's correct from the perspective of the power supply. basically there's an impedance of around few ohms from the main supply to your logic ic. current spikes across that impedance result in a voltage drop at the ic supply pins which can drop below the voltage requirement and result in fucked up logic. a bypass capacitor presents milliohms of supply impedance for short spikes, which eliminates this problem.

>>1114036
Lmin is 27uH at 100kHz (MC34063)
I'm looking at 0504 inductors, there is one that's 33uH/0.88A, the datasheets don't say anything about saturation current they only state max operational current

>>1114040
if the datasheet doesn't have an inductance-current plot then i wouldn't use that. it's probably a ferrite inductor and you can't be confident its inductance won't drop out sharply at 0.9A.

it's a little borderline because i'm respecting your aggressive sizing but look at NRS5030T330MMGJ. shoot for a 47uH anyway because dc dc converters can get pretty nasty looking outputs when you use the minimum values before considering esr.

I'm planning on becoming an electrician. I'm around 2 metres tall though, would this be a profession suitable to my size? Is there alot of squeezing into cramped spaces involved in being an electrician?

Another stupid question... Is being an electrician tradesman the same as dealing with electronics or is that a separate occupation altogether?

>>1114051

2 meters is good for working overhead, but is a small disadvantage in most other things, like reaching inside a wiring cabinet, etc. both plumbers and electricians tend to be compact.

an electrician is completely different from an electronics guy. sparkies work on high voltage, high current stuff: motors, relays, lighting, control panels, heating, ventilation. occasionally you deal in low-voltage electronic stuff, like a motor speed controller, but you dont deal with these things in depth. you essentially wire them as per a diagram. an electronics guy would be able to able to actually fix such a motor controller, whereas the sparky just pulls it out and sends it away for a replacement.

>>1114080
Thanks Anon that's really helpful. I hope to become good at both occupations someday.

I'm working on a project that will need to move a laser pointer and camera.

I'm looking at a pan tilt kit with servo's right now. Is there a better method to get something like a smooth ball motion? The actual system would be either ceiling mounted or mounted on a wall.

Hopefully I described this well, I think I didn't.

Welp.
This is what it took to finally get the basics through my skull.

I'll just have to live with being a 89IQ retard I guess.

>>1114170
i wanna fuck voltage

>>1112132
>E for voltage instead of V or E
>W for power instead of P
Why does this exist?

>>1114170
>89IQ retard
You mean 89IQ weeb?

>>1114228
>Why does this exist?
For little minds like yours to find something to bitch about.

/ohm/, I want to make an RC car from scratch, with the only IC I'm allowing myself to using being op-amps. Right now, I've got two choices that I'm trying to decide between:

1. Use a ~40kHz carrier wave and do simple amplitude modulation. Pros: Easier to build Cons: No way to get a nice 1/4 wave antenna, so lower transmission power
2. Build an oscillator in the tens of megahertz, and build a frequency mixer to allow the use of an intermediate frequency. Pros: Can use a nicely harmonic antenna for better transmission power. Cons: Much more complicated

How much of an issue should I expect having an antenna length much, much less than lambda to be? I'm not trying to do anything crazy with the project, just have the car go forwards or backwards while I'm in the same room.

>>1113353
I think this is only available to universities through fabs like MOSIS. I don't think there's an equivalent like oshpark for pcbs.

>>1114259
>Use a ~40kHz carrier wave and do simple amplitude modulation

that's nuts. if you're gonna xmit at 40Khz, you might was well do it with IR leds instead of radio, and use a ready-made 3-pin receiver/decoder from an old TV or VCR.

>Build an oscillator in the tens of megahertz, and build a frequency mixer to allow the use of an intermediate frequency.

equally nuts. first, it's better to be working around the FM band, cause then you can use any old radio to test if your transmitter is actually transmitting. this also means you can use a pretty small antenna. secondly, a simple 2-transistor hetero-dyne is all you need for a receiver. no need to replica a proper radio if all you need is simple ON/OFF control.

of course, there' all kinds of cheap 433Mhz little boards you can get if you abandon your aversion to using chips.

>>1114228
oh shit my curly cursive "E" I copypasted from wikipedia didn't work

>>1114030
You need bigger coils. Inductor current ratings are dictated by saturation current rather than power dissipation.

If it was just power dissipation, 10% more current means 20% more power dissipation which eats into safety margins rather than the device failing as soon as you go slightly over.

If you exceed the saturation current, the effective inductance drops to almost nothing and dI/dt goes through the roof.

>>1114228
Just wait til you get to quantum field theory

>>1114154
A pan/tilt assembly is what you want, unless you have some particular requirements (and a substantial budget, although even then that usually translates to a better pan/tilt assembly).

The main thing is whether you need >360 pan (i.e. the ability to track something that's orbiting the camera).

>>1111134
What are those fukken called again?

>>1114437

pixie boobs.

>>1114438
Cool.

>>1114437
Nixie tubes. Or numeric indicator tubes.
1488 is some play nazi codeword.

I want to generate a square wave from the input of my microphone and thought I can just use an op-amp as a comparator but I don't get any plausible output from it.
I am a newb and don't know if this should work.
I don't have an oscilloscope so I can't check the waveform from the mic and don't know how I sould connect it. pls halp

>>1114627
forgot pic

>>1114627
just make a diode clipper and put it on one of the amplifier stages

>>1114627

> square wave from the input

a microphone has an input of sound and and output of an audio signal. that doesn't make sense.

what are you trying to do? Are you trying to frequency modulate a square wave using an audio signal?

>>1114633
When I speak into a microphone I get a sinewave and I want to get an square wave with the same frequency.

>>1114635

probably just AC couple and use a schmitt trigger

>>1114635

all you have to do is increase the gain until it starts to distort, then increase it some more. there was a voice-recognition chip that used this technique of sampling squared waves and determining the sound by the pulse widths. it used an LM324 to amplify a mic, and over-driven to create square wave voice signals.

here is a useless schematic from Radio Shack, maybe you can find a clearer version by googling the voice chip: VCP200.

>>1114640

the EEVblog fag did a video about it, and made a better schematic: https://www.youtube.com/watch?v=kFth9K_IvwA

>>1114627
Can you provide more detail about the application? What is the microphone supposed to be picking up, and is the square wave supposed to be strictly periodic? Because if it is, that's only going to work if the microphone only picks up a pure frequency, which is unlikely.

>>1114686
I want to generate a square wave so I can determine the frequency on a microcontroller. I want to pick up whistling/ humming.

>>1114691
You'll have a much easier time doing an FFT with the audio input, if it has analog IO.

If not: feed the microphone output into a comparator with whatever VBias for the mic is as the other input. Have the comparator be supplied by twice VBias and ground, then attenuate to logic level.

You'll still be picking up noise, and I don't think whistling or humming will be pure frequencies, either.

>>1114697
> I don't think whistling or humming will be pure frequencies, either.

if you watch the video from >>1114645
at 24:26 for example, you can see that whistling and humming do produce reasonably pure sines.

New thread:

>>1115120
>>1115120
>>1115120