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/diy/ - Do It Yourself


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File: 129 KB, 1000x769, 1417560666644.jpg [View same] [iqdb] [saucenao] [google]
806660 No.806660 [Reply] [Original]

Old thread:
>>799233
>I'm new to electronics, where do I get started?

There are several good books that are commonly recommended for beginners and those wanting to learn more. There are also plenty of good Youtube channels that teach about the basics as well as advanced concepts. The best way to get involved in electronics is just to make stuff. Don't be afraid to get your hands dirty. Take something apart or build something you find cool on one of the many electronics websites.

>What books are there?

Beginner:

Getting Started in Electronics by Forrest Mims III
Make: Electronics by Charles Platt
How to Diagnose and Fix Everything Electronic by Michael Jay Greier

Intermediate:

All New Electronics Self-Teaching Guide by Harry Kybett, Earl Boysen
Practical Electronics for Inventors by Paul Scherz and Simon Monk

Advanced:

The Art of Electronics by Paul Horowitz

>What Youtube channels are there?

https://www.youtube.com/user/EEVblog
https://www.youtube.com/channel/UChturLXwYxwTOf_5krs0qvA
https://www.youtube.com/channel/UCosnWgi3eorc1klEQ8pIgJQ
https://www.youtube.com/channel/UChtY6O8Ahw2cz05PS2GhUbg
https://www.youtube.com/channel/UC1rxMIOt82ieNE19w15U5YQ

>What websites feature electronics projects? Where can I get ideas for projects?

https://www.adafruit.com/
http://www.instructables.com/tag/type-id/category-technology/
http://makezine.com/category/electronics/

>Where do I get components and lab equipment from?

http://www.jameco.com/
https://www.sparkfun.com/
http://www.ramseyelectronics.com/
http://www.allelectronics.com/
http://futurlec.com/
http://www.ladyada.net/library/procure/hobbyist.html
http://www.mouser.com
http://www.alliedelec.com
http://www.newark.com
And sometimes even just ebay.

>What circuit sim software do you use?

This mostly comes down to personal preference. These are the most common ones though:

NI Multisim
LTSpice
CircuitLab
iCircuit for Macs

>What software should I use to print circuits

Circuit Wizard
ExpressPCB
EAGLE

>> No.806667
File: 166 KB, 823x350, 46_1168774997.jpg [View same] [iqdb] [saucenao] [google]
806667

Hello, /ohm/ i'm desolated.
It's been about 2 months and I'm not able to find the problem on the power supply that I built. (Pic related).
The problem is: If there is a resistive load on the output, I can drain 5A on the output with out the voltage droping a single mili volt.
If I conect a goddamn capacitor on the output and then conect a resistive load on the output the voltage drops 1 to 2 volts. If I remove the capacitor, everything goes back to normal.
Because of that, there is no capacitor on the output of my power supply at all, and this is getting me really insane. There is nothing wrong on my my circuit, the same schematics on the pic related is the same circuit I build I changed nothing. If anyone out there can help me I would be very grateful.

>> No.806673
File: 11 KB, 238x370, 1.jpg [View same] [iqdb] [saucenao] [google]
806673

Hello /ohm/!
I have a question - how does the circuit in the attached picture works and what is its purpose?

>> No.806675

>>806667
Sounds like it starts to oscillate when you add the capacitors. Part of the reason is how the transistors are connected.
Bigger output capacitor would probably be the easiest fix.

>> No.806676

>>806673
Looks like an oscillator producing pulses with fast rising edges. Collector voltage rises, transistor goes into avalanche, capacitor discharges, transistor turns off, repeat.

>> No.806677

How big is that capacitor?

As US1 has literally no load and acts as cheap voltage reference only you might have too much off a capacitive load.

>> No.806678

>>806677
>>806667
forgot to qoute

>>806675
oscillate - yes probably, bigger cap - no

>> No.806679

>>806673

I'm probably stupid, but I can't see this circuit doing anything. Basis on the transistor is connected to ground?

I could make it into an amplification circuit if i connect them differently.

Or maybe I read the schematic incorrectly, and it is meant to amplify the negative aspect of a waveform centered around 0V, for example a sine between +90V and -90V, this would amplify the part that is below 0V.

I'm probably wrong on all accounts here, so can someone please answer him correctly? I haven't done amp circuits since the 90's, and I just realized i need a refresher.

>> No.806680

>>806677
>>806675

If I put a 10uf 35V cap on the output it starts to mess up.
Could you explain me more why the transistor connections messes my circuit?

>> No.806683

>>806678
>>806680
If I add a bigger cap on the output, it ocilates more!!
I added a led on the output together with the cap and the led is blinking.

>> No.806688
File: 638 KB, 823x708, cheap circuit.png [View same] [iqdb] [saucenao] [google]
806688

>>806683
like I told you here >>806677

This circuit is a really bad one for capacitive load. Have attached a pic of how to fix your circuit, ofc you have to recalculate some resistors for the +0.7V drop over the diode (V1) or the difference to the zener voltage of V2.

I recommend removing the voltage regulator and just use a zener diode as reference. If you want to keep the adjust-ability then go with V1.

>> No.806691
File: 130 KB, 1280x800, duuuuuude.jpg [View same] [iqdb] [saucenao] [google]
806691

>>806683
I have this crap pocket osciloscope that saved my life many times and I measured the output of the power supply when a cap is connected. It realy is oscilating(pic related).
What can I do in order to fix this?

>> No.806692

>>806688
and if you want to know why: even linear DC/DC converters have a phase and frequency response, the cap acts as a low pass lowering phase margin to a point lower than 55°, even 50/60/110Hz can be enough to get to that point with low cost regulators.

Further explanation requires understanding of complex numbers and Laplace I'm afraid.

>> No.806694

>>806676
Thanks! I've read an article on wikipedia on transistors working in avalanche mode of operation, and that was my initial guess, but I wasn't sure if I was missing something or not. I'm still new to this stuff. Thanks again!

>>806679
If my understanding of http://en.wikipedia.org/wiki/Avalanche_transistor is correct, then if you bias a transistor like that, you can get really fast switching times due to avalanche breakdown. So it's a pulse generator with very fast rise times.

>> No.806705

>>806680
The basic problem is that your transistor additions have gain and this additional gain makes the circuit unstable (LM317 wasn't designed it in mind) when you add little capacitance to the output.
The simplest fix would be to try to swamp this by using (much) bigger output capacitor. It's not always practical, though. Other options would be to add more intelligently placed compensation capacitors (from that transistor shit to LM317's feedback pin, perhaps) or lowering the booster circuit's gain.

>> No.806708

>>806688
I tried the v1 fix and it screwed the psu a little more.
When I connect a capacitor, everything works well. whan I add a resistive load, the psu drops almost 2 volts

>> No.806712

Is there a better design that I can still reuse my 2n3055?
something with op amp.

>> No.806724

I've been told to make my LED clock I should use WS2803 if I want RGB LEDs, but I'm going to need 10 of those chips for a 4 digit clock because each digit has 15 segments.

Also:
>Nobody really uses I2C to connect a microcontroller to a chain of shift registers.
>You're a beginner and [I2C]'s more complicated than SPI.

I dunno. I don't understand how I'm supposed to learn about any of this stuff. That WS2803 isn't even on any of the stores listed in OP. It's for sale elsewhere, but like... what... I dunno.

>> No.806737

Anyone here knows any good literature related specifically to PCBs?

I need to do a paper describing the whole manufacturing process and I'd like to not just copy everything from wikipedia

>> No.806739

>>806724
>I dunno. I don't understand how I'm supposed to learn about any of this stuff. That WS2803 isn't even on any of the stores listed in OP. It's for sale elsewhere, but like... what... I dunno.

That looks like a SPI interface tho?

http://www.digikey.com/product-detail/en/TLC5955DCAR/296-41090-1-ND/5181351

two of those should get you fixed.

Also, digikey is the place to go for rare parts.

>> No.806756

>>806739
>That looks like a SPI interface tho?
Yes. The person I quoted was trying to discourage me off trying I2C, and {for SPI} suggested the WS2803.

>TLC5955DCAR
That says it was 48 outputs, divided by the 3 RGB pins means 15 RGB LEDs per chip, so I'd need 1 of those per digit, so I'd need 4 of them, which would cost $24 instead of $10. Less components, but doesn't seem like it'd be worth it. Unless it can somehow hook up multiple RGB signals to the same pins and then toggle them on/off with other pins, but the guy who gave me advice last time said that was a lot more complicated and at least the WS2803 was incapable of that. It's stupid that I can't set a global RGB value for them all.

>> No.806760
File: 150 KB, 1920x1080, ohm challenges.png [View same] [iqdb] [saucenao] [google]
806760

Challenges!

>> No.806761

>>806737
Like the industrial manufacturing process with wave soldering and shit? Or do you just want to DIY a board?

>> No.806768

>>806760
Saved!

I made a coil gun once, but when I charged the cap bank with 550J parts of the ground plane got vaporized when I pulled the trigger.

Yes, vaporized.

>> No.806773

>>806761
The whole industrial manufacturing process, from the design to the final product (not including casings or what ever comes after the pcb is made).

I don't have to be really thorough as this is just a 10-15 page work, but i'd like to learn something along the way

>> No.806807

>>806676
And the transistor doesn't break?

>> No.806814
File: 105 KB, 669x564, fmmt415.png [View same] [iqdb] [saucenao] [google]
806814

>>806807
Use a big enough capacitor and sure it breaks.
Google FMMT415's datasheet. It is specifically rated for this use. Pic also related.

>> No.806819

Does anyone have any experience hooking multiple rotary encoders up to a microcontroller? they'll be driven at about 240 pulses a second and I'd like to have them hooked up to the same (small) 5v microcontroller. I guess the teensy has enough interrupts but it runs on 3.3v, the arduino pro mini is something im comfortable working with but it can only handle one encoder at a time, any board suggestions?

>> No.806838

>>806760
Buahg

>> No.806850

I have nothing to do all summer so I might as well learn electronics. I have done the first year of an electronics degree but that has mostly just taught me maths.

Any good projects to start with? Which soldering iron should I buy? etc

>> No.806884
File: 125 KB, 640x480, muh_spoilzz.jpg [View same] [iqdb] [saucenao] [google]
806884

I just won an auction today for 5 traffic signal heads. I got a summer project now, gonna build my own sequencer to control the lights. I think they're LED unfortunately, I'd rather have incandescent but for $60, who's gonna complain?

>> No.806949

>>806760
Number 58, what's a nickelodeon?

>> No.806973

>>806884
Did you buy traffic lights just to make a sequencer?

What do you plan on doing with the lights once you've made the sequencer?

>> No.806974

>>806850
For starting out buy the cheapest shit you can get.

Once you're interested enough, you can go buy better ones.

Otherwise you'll be just wasting money.

>> No.806980

>>806850
I bought a $20 analogue temperature control iron about a year ago with the intention of upgrading it but it hasn't skipped a beat.

http://www.hobbyking.com/hobbyking/store/__24790__Soldering_Station_with_Adjustable_Heat_Range_with_US_Plug.html

I bought it just for my hobbies and the odd time I bought work home. It's a great starter. After that get some 60/40 or 70/30 solder and that should be fine for your needs. I prefer 1mm for most of my work.

>> No.806998

>>806980
that soldering iron has served me very well over the past year

>> No.806999

I posted this on /g/ the other day but didn't getting any reply:
I'm thinking of using a couple of sliders/dials to control certain functions in GIMP/Photoshop/etc. (brush size, brush hardness, opacity, etc.)
However I haven't done any electronics project, outside of the odd repair soldering. So I really have no idea how to get started on something like this or how complicated it would be.
At the moment I'm thinking of using potentiometers as input for a Arduino Leonardo and then connect it to the PC as a Keyboard or Mouse (which the Leonardo can do natively)

>> No.807006

>>806999
> So I really have no idea how to get started on something like this

<!--begin script preload-->
<script language="javablabla">
<dial class="code">
you need to reverse engineer the photoshop code to find out what triggers the negative and positive values of each property. You then crack it to assign the mouse wheel for it. Look for microsoft mousewheel datasheets.
</dial>
<dial class="slider">
Just imitate the mouse wheel behavior in your slider
</dial>
</script>
<!--end script preload-->
<!--begin loading reversed code here-->

>> No.807042

>>806973
I bought the traffic lights just because I've always wanted one to hang somewhere. eBay has exorbitant prices and expensive shipping to boot. Now I have some lights so I'm going to see what I can do with them.

>> No.807085

Complete retard here, just one quick question

If through-hole design's production can't be automated, does that mean we can only use EDA tools with SMD components?

>> No.807090

>>807085
>If through-hole design's production can't be automated
But it can be automated. There are machines which populate the PCBs and machines which solder them. Have been for decades.

>> No.807093

>>807090
Why is SMD better for mass production then? Is it just easier to automate?

>> No.807097

>>807093
The components and the resulting devices can be smaller, lighter and cheaper. These alone are more than sufficient reasons for preferring SMT.

>> No.807101

>>807097
Alright, makes sense. Thanks

>> No.807110

>>807093
Through hole components require a human worker to insert. They don't work with pick and place machines.

>> No.807116

>>806676
Where do I learn to detect shit like this guy?

>> No.807145 [DELETED] 

How is a single electricity directed between a gorillion gates so it reaches the correct memory cell?

>> No.807161

So I have an idea for something, but I am having trouble finding a place to start.

I love game trainers. You know? The thing where you can search for values in a video game and edit those values to get shit like infinite lives? The Gameshark for the Gameboy Color had one and several emulators I've seen have them.

My question is, how would I go about making a game trainer for something like the 3DS or other handheld/console using an Attiny or Arduino?

Does anyone know of any great sites to read about game trainer theory and learn taht way how to do things?

I know this seems like an odd concept, but I loved my game trainers and the ability to mod everything through a little bit of work was a blast.

Thanks in advance, guys and gals.

>> No.807169

>>807110
That's just plain wrong.
However, there are cases where it makes more sense to insert and even solder the through-hole components manually.

https://www.youtube.com/watch?v=2sm_qdeconI

>> No.807250

Hey everyone,

I am wanting to connect to an SNES or SNES controller and allow for external inputs via the internet or even text message, a la Twitch Plays.

What would be the best way to accomplish this? I want to do fighting games with friends via voting and take bets.

>> No.807363

>>807250

first you need a micro-controller that has an internet stack. the RasPi is the obvious choice. then you need to learn a programming language to communicate with a server, and do I/O to interface with the NES. Ruby is the obvious choice. then you need to create a server somewhere on the net to talk to all these RasPis. or you could overlay your instructions on some existing servers, such as IRC. lots of work needed.

>> No.807366

So I have an LM317, LM337, some giant ass capacitors, a dual gang pot, and a 24 VAC center tapped mains transformer. I intend to build a split supply, which itself is pretty easy.

I'm fucking terrified of mains voltage, and building something that uses mains voltage. How do I make sure I don't get electrocuted?

Also my workbench has a stainless top. Is it a good idea to ground my bench? Can anyone give me some safety pointers so I don't electrocute myself?

>> No.807373

>>807366

nobody dies from 120V, dude. you just feel a little tingle, at most. children under 6 have been known to sleep right through electrocution accidents at 120V.

so first thing is to stop being a child afraid of shadows. second thing is to isolate all the 120V bits with tape or heat shrink. if you use a fuse and a switch on the 120V line, you have at most 6 points that are connected to the plug. once you tape all those up, you are completely safe from touching a live wire.

thirdly is to stand well back when you first try it. use a broom-handle to flick on the switch from a distance. then get closer and take measurements until all your irrational fears are gone.

>> No.807392

>>807366
Make sure the power is completely off and disconnected before working on your project.

Test your thingamabob on a GFCI outlet. If you don't have one, you can get GFCI power strips, or you can make a GFCI outlet box with an extension cord that plugs into your ordinary wall power socket.

Grounding your benchtop is optional. GFCI devices will protect you from hot-to-ground and some other faults since they basically just measure the difference between the currents through the hot and neutral wires. If the electricity isn't coming back through the neutral wire almost exactly the same as it's going out the hot wire, that means some of it is going somewhere it's not supposed to. So it cuts the power.

Don't leave any exposed wire ends. Try to keep everything tidy, use electrical tape and heat-shrink tubing to reduce the risk of shorting accidents. If you use wire nuts, put a little piece of tape around the wires to secure them together, in case the wire nut becomes loose.

Build everything in some kind of box or enclosure. It is a good idea to ground the enclosure if it is made of metal. Otherwise I would recommend a non-flammable thick plastic. Wood is combustible and it doesn't have such a high dielectric strength so I would be careful with wood (but don't count it out entirely)

>> No.807409

>>806760
so let's roll

>> No.807410

>>807409
is VFD good too?

>> No.807412
File: 105 KB, 600x600, cover_ridethelightning_lg.jpg [View same] [iqdb] [saucenao] [google]
807412

/ohm/'s official soundtrack.

ontopic: How much time do I need to spend before I literally "hold the lightning in my hands" ?

>> No.807650

>>807363
I have a Beaglebone Black and a Raspi. Which is better for this endeavor? I appreciate the help. I just need a direction to go.

>> No.807652

>>807650
Doesn't matter, flip a coin if you have to.

>> No.807678

looks a oscilator, none input one output, but pase polarization seem wrong

>> No.807872

I have a CR2032 set up with 10 LEDs all parallel. What resistor value should I use to make them light up at a moderate level and last long?

>> No.807883

>>807872

the CR2032 has a short-circuit current of around 20mA so you dont need any resistor. also, it has a capacity of around 220mAh so it wont last very long, maybe 30 mins.

>> No.808382

My WES51 came with this black rod with a magnet at one end. Anyone know what this is for?

>> No.808391

Anyone have a guide to converting a APC to accept 1v/oct from a eurorack seqencer

ty

>> No.808401
File: 1.94 MB, 2448x3264, 2015-05-04 23.29.41.jpg [View same] [iqdb] [saucenao] [google]
808401

>>806660
So I'm the guy that accidentally built an AM radio while trying to build a lightning detector. After letting the smoke out of a few transistors and overheating my power supply at least once, I've refined it a little bit. The antenna I'm using is a large steel table, something like 24"x60".

You have to tune the base voltage of the first transistor using the pot to right above where you're picking up an AM radio signal. I've read about this configuration, and it kind of works like an adjustable diode.

Even with a clear sky, it pops and crackles with some livelihood. If you tune it right, it's sensitive enough to pick up my lipo charger from many feet away, and it emits a click when you turn a light on or off. It also picks up appliances switching on and off, and cars starting outside. I added a low pass filter to cut all of the high frequency garbage that was getting through, and so the transistor wouldn't saturate and start melting shit.

I just built this with parts I had on hand, tinkering after work every night. I'd love it if someone tried to replicate it or make some improvements. I was aiming to use the fewest components I could.

>> No.808407

>>808401
I just measured it, and with an indicator LED on my breadboard, the whole thing draws 35 mA at rest (or so my multimeter says).

As a caveat, I have no idea what the hell I'm doing.

>> No.808409

>>806819
ayy so i did some more research and i guess on an arduino mega (the easy route) I could just use 4 inturupts, but what if the two encoders overlapped? would i lose a signal? would it be best to have smaller microcontrollers handle each motor/encoder set? i just need to make sure that i catch at least 95/100 pulses so I dont lose much position per movement

>> No.808413

>>808409
Consider feeding into counters that you check at a set rate instead of interrupts.

>> No.808415
File: 1.06 MB, 2592x1456, IMG_20150502_163438073.jpg [View same] [iqdb] [saucenao] [google]
808415

I have this N3015 oscilloscope. 1983 made. Can I use it for daily, 5/3/12V work?

>> No.808423

>>808401
A simple lightning detector is basically a bad AM radio. You can expect a two-transistor circuit like that to detect any and everything even remotely "lightning-like" as a lightning.

If the thunderstorm is near enough, the signal strength is so high that you can even use a normal scope to see the strikes, if you attach a small antenna to it.

You need signal processing if you want better performance and reliability. There actually is a lightning detector IC with built-in filtering.
http://ams.com/eng/Products/Lightning-Sensor/Franklin-Lightning-Sensor/AS3935

>> No.808446

>>808409
If it's only 240 pulses per second or less, you could just rig the processor to get a timer interrupt at a reasonably high rate (say, 2400Hz), sample all the encoder outputs and decode movement. Remember to sample all the outputs simultaneously (with a port read, instead of a bit read) so that you won't get skew-related errors.
This also guarantees your processor won't get excessive amounts of interrupts when one of the encoder outputs chatters for whatever reason.

>> No.808447

>>808415
You know that best. Why do you think it's not suitable for your purposes?

>> No.808450

>>808447
Is it capable of displaying 3v/5v/12v DC? Because when I connect it, it displays a square wave, but with empty space between the waves. It's just a moving dot. Other then that, it can only display max 200ms, is it always that low for scopes? I would like atheist 1 sec.

>> No.808451

>>808450
I use it to display 1 sec signals

>> No.808469

>>808450
It's an analog oscilloscope. They draw the waveform using that dot. If the sweep speed is very low, you can see the dot. You need a scope with memory to "fix" that.
Square wave with fast enough edges will look like two dashed lines. It'll look like that even on scopes with memory.

Looks like it has a switch for AC/DC input selection and the input attenuator covers the range you want.

>> No.808714

>>806949
I'm not sure, but I think its a small device that plays a film when you put money into it

>> No.808715

>>806949
It's those things you drop a nickel in and then it animates a short clip by having you crank it.

>> No.808732

>>806760
rollin

>> No.808744

Hey /ohm/,

I'm that crazy Anon who is trying to recreate "TwitchPlays" through a Raspberry Pi's GPIO header connected to a controller.

I am new to the concepts of the GPIO. I normally stick to electronics that involve shit like 555 timers and junk like that. This is a new endeavor for me.

I'm gonna explain what I want and I'm hoping someone has some ideas about how I can accomplish this.

Greentext for simplicity:

>Hear about TwitchPlaysPokemon
>Want to do own version using fighting games
>Will take bets on fighting games using Magic cards because my Friendly Local Game Store likes vidya
>Am using a Gamecube and Melee since Melee uses seven main buttons: Four directions and X, B, and A
>Don't need L, R, or Z because shields and grabs
>Soldered wires to the pads on the controller and to the variable resistors on the analog stick
>Connected new wires to Arduino digital pins for testing
>Can make characters jump, attack, and special
>Can't figure out how to make them move in four directions despite jacking directly into variable resistor
>Want to wire controller pad wires to GPIO header on Raspberry Pi
>Want to communicate with header over internet and allow people to send commands from phones and shit


Does anyone have any ideas about where I should go from here?

>inb4 "Fucking Quit, OP"

No, I'm having too much fun. I just hit a snag is all.

I forgot to mention that the signal from the GPIO has to be "LOW" in order for the buttons to work. When you press a button on a controller, it connects to ground, which makes it work.

Not 100 percent sure how the fuck an analog stick works to be perfectly honest

>> No.808752

>>808744
Sounds like yo're off to a good start. Controlling the buttons of an RPI header shouldn't be any different than controlling them from an Arduino at an electrical level. They're both TTL push/pull outputs. You've got to install some libraries to work with them from a program/script on the RPI, lots of tutorials on that available.

>>Can't figure out how to make them move in four directions despite jacking directly into variable resistor

The joystick potentiometers are wired to form a voltage divider that creates an analog level at the wiper (center pin). To do a good job you should remove the potentiometers and control the wiper points with a DAC. For a so-so job you should be able to leave the potentiometers in and control the wiper point with a single GPIO output. This will give you some level of forwards and reverse by bringing the GPIO low and high, as well as stopped [centered] by bringing the GPIO pin to high impedance.

>> No.808761
File: 7 KB, 184x274, fodiy.jpg [View same] [iqdb] [saucenao] [google]
808761

Hi there hi/diy/ous people, just touching on the first chapter of resonance in my EE book. I get the jist of how a LRC can pick up certain frequency but am a bit baffled as to how the workings of those components are able to filter out a particular frequency, I gather the controls on the front of a radio can vary the inductance and capicitance values but how does it all actually work?

>> No.808762

>>808752

I'm not interested in precision when it comes to the analog stick. Everyone is going to be mashing buttons anyway, so I think just full on and full off will work best. What is the difference between high and high impedance when it comes to GPIO?

>> No.808767

>>808762
A GPIO pin in the high impedence state is not connected to VCC (HIGH) or GND (LOW). This state is normally used to read inputs, but it can be used as a third output state in some circuits.

When using high impedance output imagine it like the GPIO pin is just disconnected from everything (an open switch). In this state the only effect on the wiper voltage will be from the potentiometer, so it will read as centered provided nobody's touching the stick.

>> No.808774

>>808761
air variable capacitor
or
varactor

>> No.809008

Anyone know where I can get a transformer thats AC-DC, about 18 watts.

Ridiculously hard to find online.

>> No.809016

>>809008
>AC-DC
Calling it a power supply instead would probably produce better results.
>about 18 watts
Bigger is ok.
You also need to know voltage and probably things like plug/connector types also matter.
Now try again.

>> No.809027

>>809008
Transformers are AC-AC. Either stepping up or stepping down the voltage.
Usually nameplate ratings are in Volt-Amperes

>> No.809170

I have something weird going on.

I have connected an LED to my GPIO on my Raspi, but it blinks for some reason. I haven't run any code yet and the only thing I have installed is WebIOPi. Anyone have any ideas?

>> No.809176

>>809008
>18 watts
Voltage and current matter. What are you powering? Also transformers by nature only put out AC.

You can wire up a bridge rectifier and a few capacitors to get output from a transformer into DC, and then step that down with an LM317. Super easy and cheap circuit to build, and one everyone should have on their bench. If you don't want to do that, you can buy self-contained switching converters. But those dump all sorts of RF noise, and can get kind of expensive.

Obviously be careful with mains voltage. Shit is dangerous as fuck.

>>809170
I know at least on the arduino, pin 13 is used as some kind of test pin and is connected to an LED on the board that lets you know shit is happening. Could just be a diagnostic feature that's there to tell you that nothing has had its ass ripped out.

Just a guess. Never played with a raspi.

>> No.809521
File: 1.62 MB, 3264x2448, IMG_8394.jpg [View same] [iqdb] [saucenao] [google]
809521

Hey /diy/,beginner here interested in making circuit producing a 40kHz frequency current outputting a 60watt ultrasonic motor.

My biggest question is; which resistors are in series/parallel? Are the capacitors in series/parallel?

Also will current rate (amperes) be affected by the time it reached my motor?

>> No.809564
File: 112 KB, 500x440, 555.gif [View same] [iqdb] [saucenao] [google]
809564

>>809521
All the resistors are in parallel, the current get's divided through all of them. The capacitors aren't in series or in parallel, since they are not connected together in any way, and they act independently, specially in a multivibrator like yours.
Be careful when analyzing that circuit because it's unstable, currents won't be constant.

I've never seen a such a powerful multivibrator, neither one that works at that frequency, or at least with much precision.
If you just want a 40kHz square wave I would use gif related, a pot would allow you to choose the right frequency, for the power thing, just attach a power mosfet to the output.

>> No.809588
File: 16 KB, 450x292, 94.jpg [View same] [iqdb] [saucenao] [google]
809588

>>809564
Going to work on calculating values with the 555 chip tonight. Yes I wanted to add a pot, would that be in place of the voltage divider to the left of pic related?

Also I think 555 chips can take voltages between 4.5-15V, 18 being absolute maximum. Though it'd be pushjing it, I theorize my 12V 7.6A supply won't do harm to the chip.

>> No.809635
File: 854 KB, 1632x2200, DSC_0950.jpg [View same] [iqdb] [saucenao] [google]
809635

>>809588
You can change R2 for a pot. 12V are no harm to it, you aren't even driving inductive elements that can generate kickbacks.
I recommend you an IRFP250 mosfet, that's the one I used for my flyback driver, I even got to run it with 42 volts 3-4 amps (around 150W) isolating the 555 with a 7812.
For lower powers (130W max) I use the IRF540N, the bad thing about this one is it's a TO-220 and its more difficult to heatsink.

>> No.809641

>>809588
Forgot to mention, if you've got an android phone, Electrodroid is a neat free app with many info and calculators (including 555 timers) for electronic hobbyists.
I also use Everycircuit to simulate circuits on the go.

Maybe they should be added to the catalog as handy software tools.

>> No.809649

So with the maximum character limit in the OP, why don't we just make a pastebin and just link it instead of pasting the entire OP each time. That way we can get more information in the OP post and we won't have a character limit.

>> No.809664

Thought I'd ask here at the risk of getting flamed but I'm trying to repair my aux cable. I stripped down the rubber around the cord and exposed two wires which I'm assuming is positive and negative, no other wire is present so I guess no ground wire? Anyway, so the problem with the cord was loose cables near the aux jack so I just got rid of the jack altogether. Basically what I hope to accomplish is to join half of the aux cable and half of another cable with an audio jack, and hopefully fix the issue. As I said before, the aux cable only had 2 wires present but the other cable has 3, with the 3rd wire being the ground.

Aux cord wires are red and white. I have no clue which is pos and which is neg.

Other cord wires are red, gold and blue.

I'm assuming that both reds are positive, white from aux and gold from cord might be negative? I don't know but I would appreciate help.

>> No.809677

I'm going to try and adapt a basic microphone pre-amp as a dedicated amplifier. I didn't realize until today that I had put together a biased circuit to amplify a DC analog (0-5V) to AC (+/- 12), while another circuit, meant for a microphone, actually had a DC blocking cap, because an electret microphone requires a DC bias. It might not really get me anywhere, as I definitely wanted that +/-12, BUT it might allow me to test out an AC amplifier/buffer for use with a usb dev board.

>> No.809740
File: 18 KB, 500x304, Pptrans.png [View same] [iqdb] [saucenao] [google]
809740

>>809588
In a circuit like that the series resistor will limit the output power. To get 60W to the piezo, you'd need a very small resistor. A more practical solution would be to use a push-pull buffer stage (pic related).
I don't know what kind of piezo thingy you really have, but the ones I've seen are generally high voltage, low current types. You either need very high supply voltages to drive them, a transformer or some kind of resonant matching circuit.

>>809649
No-one has bothered to do that, that's all.

>> No.809835

>>806673
>>806676
I don't get this - How does the 2pF cap discharge through the transistor?
Shouldn't the voltage stabilize after reaching avalanche voltage as if it was a Zener diode?
Or does the transistor behave like a Zener diode with a very narrow hysteresis? Or maybe there is some time delay after dropping bellow the avalanche voltage?
Thanks in advance. I haven't met with avalanche breakdown in transistors so I'm very confused by this thing.

>> No.809852
File: 40 KB, 683x403, Ultrasonic-Cleaning-Transducer.jpg [View same] [iqdb] [saucenao] [google]
809852

>>809740
I got one of these, used in ultrasonic cleaners.

Where would this go though? I think voltage divider is to turn the transistor on/off apidly enough for 40kHz.
>>809588

R4 will be the resistor converting the 12V to 9V for obtaining 60 watt on my transducer

>> No.809854

Hello /ohms/ I have a problem.
I have a red LED powered by a coil on a NFC reader, it actually work, but the problem is that this LED is pulsing and I would attenuate this pulsing by using a capacitor, but I don't know how ... What should I do ?

>> No.809872

Could one build an analog calculator out of opamps?

>> No.810009

>>806760
Rolling.

>> No.810027

> Could one build an analog calculator out of opamps?

op-amps can be made to add, subtract, integrate, and differentiate. to multiply, you need either an analog multiplier chip, or maybe you can make one out of op-amps (google it coz spam filter is being a little bitch)

so yes, you could build an analog calculator if you were autistic enough. or you wanted a topic for a master's thesis. i'm sure some people have done it already.

> I get the jist of how a LRC can pick up certain frequency but am a bit baffled as to how the workings of those components are able to filter out a particular frequency.

coils and caps as essentially frequency-variable resistors. if you make a voltage divider where one element is a coil or a cap, the amplitude of the voltage coming out of the junction will vary with frequency. a cap at the bottom of the divider will attenuate high frequencies, a coil will attenuate low. put them together and you've created a band-pass filter.

> I got one of these, used in ultrasonic cleaners.

I once had a project involving ultrasound foot massagers. it was a long time ago, but I recall it was way more complicated that just putting a square wave on a transducer. to get any kind of power out of the thing, we needed a very precisely-tuned resonant circuit that was adjusted for each individual transducer. and this circuit put out some quite high voltages.

> the problem is that this LED is pulsing and I would attenuate this pulsing by using a capacitor

if by ''attenuating'' you mean ''make it flash less, and be more constant'' you can just place a cap across it in the correct direction (+ of cap to + of LED). the cap will store a charge when the LED is powered and dump the charge into the LED when it's not. depending on the schematic, it might make more sense to connect - of cap to ground instead of - of LED. use 100uF @ 16V for a start, and go up or down depending on results.

>> No.810095

Hey /ohm/, I'm making a benchtop power supply. Should I connect the neutral output to the chassis of the power supply as well as the ground of my dc output circuit?

>> No.810122

>>809872
Of course. Then you'll find out why people don't make analog computers anymore.

>> No.810131

>>810095
>Should I connect the neutral output to the chassis of the power supply

no, dude, the power supply should be floating, (case not grounded, no output wires connected to ground or to the case) coz that's the safest option. lots of reasons. one such reason is if you put two power supplies in series, and if their cases are touching, you'll short out one of them.

you can have a separate grounded terminal in situations where it's appropriate to connect to it.

>> No.810134

>>809835
The transistor doesn't work like a zener diode. Instead, the increasing current through it causes the voltage drop across it to go down, which in a circuit like that increases the current even more.
Ordinary neon bulbs exhibit a similar dynamic negative resistance effect and you could replace the transistor in that circuit with a neon bulb. It wouldn't be nowhere near as fast, though.
>I haven't met with avalanche breakdown in transistors
Avalanche pulsers are rarely used and avalanche is undesirable in normal transistor circuits.
Btw, you can also use the B-E diode like a (normal) zener. The voltage is around 6V, but it's said that the zener use quickly ruins the transistor as a transistor.

>>809852
Those things need hundreds of volts to produce the rated power.
You'd replace the R3/R4/Q1 combination in that 555 circuit with the buffer. Then you'd need a transformer or something to feed the element.
IMO it would make more sense to use the piezo as a part of the oscillator so that the feed frequency would always be right.

>> No.810154

>>806760
rollerino.

Also, hi, I'm new to /ohm/

>> No.810155

>>810154
Gotta reroll, I'm beginner tier

>> No.810156

>>810155
God damnit, I need something easier

>> No.810158

>>810154
>>810155
>>810156
>54
>55
>56

Those are some damn nice numbers.

>> No.810160

>>810158
Yet they're all too difficult for me.

I can barely make a counter

>> No.810167

>>810160
Why don't you just pick one which sounds fun?

>> No.810168

>>810167
Rolling is part of the game, but a stun gun sounds fun.

I've got a 555 timer and a car coil, would that work?

>> No.810176

>>810168
Sure, a 555 + a big transistor + an ignition coil would produce nice sparks and annoying shocks. No idea how stunning it would be. Probably not very.
Btw, if you use a 12V supply, keep in mind that the ignition coil produces the best spark when the switch (transistor) opens. Your transistor needs to be able to handle the kickback of the coil. If you try to (totally) kill the inductive kick, your spark suffers.

>> No.810178

>>810176
Maybe he could use something like a resistor in series with the transistor an a high voltage cap in parallel with both?

>> No.810179 [DELETED] 

Rolling so help me God

>> No.810183

>>806760

>> No.810189

Not gonna build a boolean algebra calculator in a circuit, that is excruciatingly boring. I could do it in an Arduino in a day.
Hence, reroll!

>> No.810195

>>810178
Sure, a capacitor would be one way to protect the transistor. In any case, you need a relatively high voltage transistor for it to work well.

>> No.810218

>>810134
Hundreds of Volts? I heard they require 600V excitation, but many people have them running at 110V
>IMO it would make more sense to use the piezo as a part of the oscillator so that the feed frequency would always be right.
Can you elaborate? Or type of circuit required

>> No.810219

>>806760
ROAL

>> No.810221

>>806760
Reroll because I have no idea what that means.

>> No.810261

>>810221
FSM means finite state machine.

>> No.810269

>>809740
Also Input would be connected to pin6 & RLoad would be connected to pin 2&7 on the 555?

>> No.810273
File: 1.97 MB, 3264x2448, 2015-05-09 14.27.39.jpg [View same] [iqdb] [saucenao] [google]
810273

>>810261
Does this count? It's kind of a mess, but if you ground any of the 3 red wires in any combination and push a pushbutton, a corresponding LED latches on until you push the button with the same wire not grounded. Each bit uses 4 transistors and I think 5 resistors.

It's an FSM in that you can change the input without changing the LEDs, but when you push the clock button, it they change state. Am I following the concept?

>> No.810277

>>810273
Seems about right, mind making a webm of it?
The best way to tell if you have the right idea or not is to draw a FSM diagram and see if your circuit follows the logic of the diagram. If it does, then you're good.
Usually, you do the diagram and state encodings before the circuit but not everyone is aware of how to properly do the diagram/encodings.

>> No.810377
File: 1.85 MB, 3264x2448, 2015-05-09 20.23.02.jpg [View same] [iqdb] [saucenao] [google]
810377

>>810277
Wish I had read this sooner. I took it apart because I needed the breadboard/jumpers.

It's super easy to build though. Here's a shitty schematic that I drew in my notebook. If anyone has any improvements, I really don't know what I'm doing so I'd appreciate the help.

>> No.810426

Any common electronics where I could extract a >= 100uH inductor from (preferably SMD)?
I'm building a LC Filter for a video camera, got capacitors and a diode from an old dead power supply and I'm too lazy to leave the house to go to the next local electronics store for one piece.

>> No.810529
File: 149 KB, 1535x1045, ultra.png [View same] [iqdb] [saucenao] [google]
810529

>>810218
Whatever >>809852's element needs, it won't do much with just 12Vpp excitation.
I meant building a high power "crystal oscillator", where the piezo element itself acts as a crystal. Pic related, an actual ultrasonic cleaner which does that.

>>810269
What? No.
It is an output buffer. Input goes to pin 3 and RLoad is your piezo and transformer and whatnot.

>>810426
Make an air core coil.

>> No.810555
File: 84 KB, 1361x768, citcuit.png [View same] [iqdb] [saucenao] [google]
810555

Hey /ohm/, I finally decided to pick up NI Multisim. I really like it so far. Much easier than the trial and error method I used to use haha.
Pic is a simple voltage regulator circuit for a new power supply I'm building.

>> No.810592

>>806760
trollin!

>> No.810692
File: 2.62 MB, 4128x3096, top.jpg [View same] [iqdb] [saucenao] [google]
810692

I have this old output transformer thats been sitting around, was wondering if you knew anything about it or what it could be used for.

Im not knowledgeable in electronics, I bought it around 2007 when I was aspiring to build guitar tube amps, and kinda just dropped off the idea after putting a few guitar pedal kits together.

The numbers on top read
16707
17448
138228

>> No.810696
File: 3.05 MB, 4128x3096, bottom.jpg [View same] [iqdb] [saucenao] [google]
810696

>>810692
>be 16, avid garage saler, with older brother during townwide garage sales in small city
>2007, garage sales are still decent, everyone takes part
>play guitar as hobby, but the hobby is mostly because I liked the idea of building guitars/amps/pedals
>both of us on lookout for any tube amps or radios that can be converted for guitar
>never had luck finding anything like it ever
>get to a nice enough house with an old very small house next to it, looks almost like a converted garage house
>not much of anything exciting
>one box of junk metal stuff with this transformer sitting on the top.
>ask the lady how much and she dumbfoundly goes "are you serious right now?, gonna have to ask my dad"
>she says that when she asked her father for garage sale stuff, all he gave her was the box and said that "people are gonna be fighting over this" referring to the transformer
>she goes and gets an old decrepit man out of the small house
>I buy the transformer and we kinda give him a short spiel about how we are looking for tube amp stuff, hoping he has more stuff
>he invites us inside his small house
>walk in, shelves built into the walls filled with tons of tube radio chassis
>handwrapped antennas, speakers, tubes and tools just laying around.
>lights up a tobacco pipe and goes on giving us a little tour
>he was an old radio repairman whose hobby was to build them
>he invented something and got a page in popular mechanics years ago, he showed us the page

Ended up spending close to 3 hours with this guy, because he was interesting and at same time you couldnt understand what he was saying.
Missed the rest of the garage sales because of it.
I went back one other time but nobody answered the door, felt weird so I never went again. Guy is dead by now for sure.

I had forgotten about this thing for years sitting in a box, but I had lunch with brother for his birthday recently and somehow it came up.
If it its not nice, ill just keep it around for sentimental value

>> No.810700
File: 2.57 MB, 4128x3096, side.jpg [View same] [iqdb] [saucenao] [google]
810700

>>810696

>> No.810736

>>810700
>>810696
>>810692
That is one sexy transformer.
Any way you could take the shielding off? If we can see its guts we can probably get a better idea of its details.
Based on the wiring it definitely looks like a flyback.

>> No.810741

What's the practical difference between a ground and a negative voltage? Is it just for dumping more volts?

>> No.810751

>>810741
Remember, voltage is relative. Ground is just 0 volts with respect to your reference point, which is usually your emf source.
Voltage can also have direction which implies the direction current will flow. A negative voltage just means that current is going to flow in the opposite direction with respect to your reference point.
Put a multimeter on a battery with the positive and ground leads reversed, it's negative voltage then just because you switched your reference point.

>> No.810808

>>807161
it depends, you need to insert values of some kind into your 3ds, so the starting point would be, where can you input that data, how can you connect the arduino/attiny to that port/interface.
Also nowadays is easier with plain software, keep that in mind, you don't see trainers for pc for example

>> No.810848

>>810736
>take the shielding off

You would have to wreck it to do that.

>>810696
>and said that "people are gonna be fighting over this"

Sounds like it could be a speaker transformer.

>> No.811402

>>810736
>> take the shielding off

are you retarded?

>> No.811415

Hey, a semi-retarded question, I guess:

If I want to make a triac-like dimmer like this one: http://www.ibiblio.org/kuphaldt/electricCircuits/Semi/03224.png, but I can only use thyristors. It seems to me that adding full bridge rectifier should be enough to have a circuit with the same properties. Is it right, or am I missing something?
I want to use it for AC heater control.

>> No.811417

>>811415
That was some rough sketch about the generic idea, not a real schematic.
You'd probably need to tinker with the trigger circuit, if you were to use a rectifier.

>> No.811456

>>811415

a heater is gonna be something like 12A, so if you were to rectify it, you'd need to buy 4 rather expensive 20A diodes. a Triac would be cheaper. and cheaper still would be some thrift-store wall thermostats: $2 for a mechanical one, about $5 for a digital one.

>> No.811465

What you guys think is a good EAGLE alternative? I heard good things about KiCAD, but I wanted your opinion if possible.

>> No.811493

>>811465
ExpressPCB. It's free and very easy to use

>> No.811524

>>811493
Isn't it oddly crippled, like not capable of producing Gerber files or something?

>> No.811590

>>806760
rollin'

>> No.811720

>>806884
I'm envious.

>> No.811721

>>807169
That is fucking cool

>> No.811731

I'm controlling some LED's from an FPGA on a dev board.

I have a lot of 3.3V GPIO pins that I can use to drive an LED. If I where to buy an LED with a forward bias voltage of 3.3V, would I need a resistor?

>> No.811838

>>811731
The LED current would be badly defined, varying from negligible to pretty high, depending on details like the exact supply voltage, LED type and temperature. The only positive thing is that you're unlikely to burn your FPGA pins with a 3.3V LED.
Use lower voltage LEDs or use higher supply voltage for them. Use resistors.

>> No.811852

>>811731
The forward voltage is not a sharp threshold, it's an exponential function.

FPGA outputs generally have current limiting, but it's time to grow up and Do Things Right, dude.

>> No.811861

I'm looking to make a 3.5mm audio switch, very new to electronics.

One with two switches, one to select the input [tv]/[pc] and another to select the output [speakers]/[headphones]

How should I wire it? do they make switches that will switch both the +, -, and ground at the same time?

>> No.811863
File: 61 KB, 361x361, SKU139908g.jpg [View same] [iqdb] [saucenao] [google]
811863

>>811861
Done some research, do I just need two of these and 4 female 3.5mm jacks?

http://www.banggood.com/2-Position-Latching-Toggle-Switch-9-PIN-3PDT-250V-2A-125V-5A-ON-ON-p-936489.html

>> No.811886

>>811863
yeah that will work.

cheaper way ( possibly noisier ) you could tie the grounds together and use double pole double throw switches

>> No.811890

>>811886
Thanks, I'll play it safe and get the 3 pole one.

>> No.812034

/ohm/ I need some advice.

I'm trying to get back to microcontroller programming and I want to code and flash my microcontroller through a terminal window as I do a lot of coding on my Linux system.

However, I can't seem to find a friendly way to do this with the PIC uC. There should be a way, but I'm running into multiple problems just getting simple things installed. I do have AVR series of uC but I lost the programer due to moving and will have to build my own.

So if I really want to program uC using my ubuntu system and only using terminal, am I pretty much stuck using AVR microcontrollers or is there something I'm missing here?

>> No.812266

Can anyone suggest me any projects with AVR butterfly? Does anyone have any tips/tutorials or has anyone used it before to give me some insight. I just got it to fool around but would be nice to make something productive.

>> No.812269

>>811863
you may want to make sure they're break-before-make, tying together the audio outputs of the tv and pc might have regrettable results

>> No.812281

I'm making a water equalizer, where would I find cheap small water jets? All the ones I'm finding online are for big fountains that shoot water several meters in the air. I'm looking for 1 meter at most and probably not even that high.

>> No.812314

>>812034
PIC SUCKS on Linux. But you can try doing this:

http://hackaday.com/2010/11/03/how-to-program-pics-using-linux/

It's slightly outdated but works

>> No.812321
File: 45 KB, 1280x720, maxresdefault[1].jpg [View same] [iqdb] [saucenao] [google]
812321

>>812269
Unless arcing is a concern, such switches are always BBM: they work by rocking a see-saw that pivots on the center contact, so to connect both terminals at once, the lever would have to massively deform for no reason.

>> No.812344

>>812034
Microchip do support MPLAB X and XC8 on Linux, but considering AVR programmers start at less than ten bucks (it's really just SPI) you're setting yourself up for a lot of pain for very little gain.

>> No.812353

>>812266
>this question screams "I bought this on a whim because I have too much money and wanted to look cool, not because I had an idea for a project"

Try thinking of something you hate doing and automating it. Considering it has a built in LCD, why not try making a video game like Tetris.

>> No.812364

>>806760
oh fuck it.

>> No.812679

>>806760
roll

>> No.812857

I have this plug that barely fits a 2.1 mm barrel. I need to really squeeze it in to get it to fit. What's the next closest size?

>> No.812902

https://www.humblebundle.com/books

Is there anything worthwhile in here?

>> No.813020

>>812902
The ones behind the pay more than the average pay wall look okay for some light reading, but a bit expensive. A while ago they had a bundle with a manga physics book, it was pretty decent.

>> No.813023

>>812857
2.2mm

>> No.813032

>>806999
>>807006
Rather than reverse engineering Photoshop, it's much easier to set shortcut keys (like '[' and ']' are the default ones for adjusting the brush size) and simulate those keyboard presses with an Arduino or a Teensy or something.

>> No.813183
File: 464 KB, 1920x1080, 20150514_153025.jpg [View same] [iqdb] [saucenao] [google]
813183

This was somehow part of a telephone system. I don't know what the fuck it is or what to do with it, but it looked cool and my boss said I could have it because we were going to throw it out anyways.

>> No.813193

>>813183
If you have no idea what it is, you probably can't do anything with it.

>> No.813197

>>813183
Looks like a phone exchange for company use, with 5 (or 6, if one of the connectors is broken) external lines.
Maybe someone is willing to buy it.

>> No.813199

>>813197
I'm not so much interested in selling it. I was mostly wondering if anything would be worth salvaging out of it. I'm trying to get into electronics as a hobby and don't really know what, if anything, is worth grabbing out of this.

>> No.813201
File: 2.32 MB, 3264x2448, 20141031_071527.jpg [View same] [iqdb] [saucenao] [google]
813201

Hello /ohm/
The battery in bike light is kaputt. It's a Moon Meteor 200. I've tried searching the numbers but I haven't found anything similar. Could you guys point me in the right direction? I've already contacted the manufacturer and they were of no help.

>JY 112739
>1200 mAh
>3.7 V
>120628
I'm guessing the last one is the date of manufacture (YYMMDD).

http://chxenergy.en.made-in-china.com/product/PBxnQkybaRVc/China-Lithium-Ion-Polymer-Pack-Battery-for-GPS-Medical-Device-3-7V-1200mAh-753048-.html
This is the closest I could find, but the dimensions are a little off. The longest dimension of my battery is 30 mm (37 mm if you include the fold of material with the small PCB on it) whereas the quoted dimension on the site is 39 mm.
>Minimum order: 3000

>> No.813220

>>813201
Hobbyking have a search by size thing but im not sure they would have it

>> No.813224

>>813199
>salvaging this
fuck you if it works you should just buy a buttload of phones and keep it in a cupboard in case you ever have kids.

>> No.813237

Simple question:
What is the cheapest and easiest way to wire up switch to be remotely switched?

Issues:
How to power the remote device? Putting something in series with a lamp is just asking for trouble.
What kind of signal? IR or wifi or something else?
Price.

I'm looking for something practical.
I could always just use a small arduino powered relay with seperate power but I'd rather not.

>> No.813309
File: 147 KB, 600x600, 09825-01b.jpg [View same] [iqdb] [saucenao] [google]
813309

does anybody know how to use this fucking thing (sparkfun ISP pocket programmer)?

can't get the drivers to recognize the device and I cant find an up-to-date tutorial

>> No.813329

>>813237
A long wire.

>> No.813333

>>813201
Any lipo with a 3.7v nominal will do. Probably has a JST connector on the end, pretty common.

>> No.813336

>>813237
This guy:
>>813329

I actually had this problem, and it had to be fixed in a couple hours due to an competition. I used Audio in the end.

Probably one of the more easier solutions if you want to go full EE without the Arduino shield crap you could do ultrasonic?

Remote Device.
9V Battery -> Switch -> Ultrasonic Oscillator (40-60kHz) -> Maybe Amplifier -> Piezo.

Maybe you need some sort of amplifier circuit after the oscillator. I think if you use a 555 as oscillator the voltage output will be fine at that frequency. You might need more current output but than you could use a crappy Push-Pull configuration.

Receiver:
Ultrasonic Receiver (You can buy these for small frequency ranges) -> Amplifier -> Active bandpass filter -> Latch/Hold circuit -> Some digital stuff -> Relay/Mosfet (depends on current through wire)

This last part is the most tricky. The amplifier (Opamp) used should be non-shitty, the bandpass filter tuned precisely. The Latch/Hold function should not be triggered by noise. So use a comparattor or something.


BoM:

Remote Control:
-9V Battery
-555 + Resistor/Caps
-Piezo
-(maybe) 2 okay-ish transistors

Receiver:
-Ultrasonic microphone + Resistors/Caps
-Opamp(s) + Res
-RC or LC filter
-Comparator?
-Digital Stuff like flipflops?
-Relay/Mosfet

Fucking cheap.
If you're lazy go with sparkfun IR stuff, if you want to throw away money go WiFi

>> No.813340
File: 89 KB, 982x608, 1431802341297.jpg [View same] [iqdb] [saucenao] [google]
813340

>>813237
was easier to just get something like this and mod it for what i needed.

>> No.813431

>>813309
Does the thing work at all? Do the LEDs light up, does a new USB device appear when you connect it? If you have an oscilloscope, is the crystal oscillating? Btw, a lot of what SparkFun do is tech support, if you contact them and they conclude it's broken you'll probably get a new one.

Once it's working, follow any avrdude tutorial, just select the right programmer type.

>> No.813452

>>813431

LED's light up and it shows up as an unknown device even after I download the new version of the driver, I can't get it to register on Atmel Studio.

I'll see about sparkfun tech support

>> No.813460

>>813452
A quick web search indicates that Atmel Studio doesn't support it directly and instead uses avrdude as the programming tool. Have you tried using avrdude directly?

>> No.813494

Looking to build an aluminum case for a small processor and wanted to use thermal tape to bridge the gap from the cpu to the case. It says its dielectric strength is 15 KV/mm, but does that mean it's an insulator, or that it'd take that much energy to melt the actual tape, and it does nothing to actually insulate against current?

http://solutions.3m.com/wps/portal/3M/en_US/Electronics_NA/Electronics/Products/Electronics_Product_Catalog/~/3M-Thermally-Conductive-Interface-Tape-8904-02?N=8704987+3294001773&rt=rud

this is the tape in question.

If it does not insulate against electric current, what is the standard route to insulating against charge in an aluminum case? The case is being used as a heatsink, but isn't that the norm for building with aluminum cases?

>> No.813523

>>813460

well doesn't really matter because it's still an unknown device

>> No.813527

>>813494
It means it is electrically insulating.

>>813523
Have you possibly installed other AVR programmers? For example, during Atmel studio's installation? You might need to uninstall them first.

>> No.813552

>>813494
>insulators and conductors.
anything will conduct electricity if the voltage is high enough anon. 15KV/mm just means 1mm thickness of tape will insulate up to 15KV, if you ramped the voltage up to like 16KV the tape would break down and conduct.

what kind of processor? voltage is what like 5V? 12V max? vs 15000V? no problem tape will survive.

>> No.813579

>>813336
Let me simplify the question
How can I power something permanently in that situation?
It's a 230VAC wire that's simply interrupted. Depending on the lamp that's being used the resistance and therefore the voltage drop over my device will vary. This is way out of my skillset.

>> No.813589

>>813579
If you don't want to use a battery, then your AC-DC power supply will be in parallel with the lamp.

>> No.813594

>>813199
Work out what precisely it is, whack it on eBay, and with the proceeds, buy whatever components you feel you need.

Here's a similar board from a PBX from the same manufacturer, listed for nearly $150: http://cgi.ebay.com/220558385735 . Don't scrap stuff that's perfectly functional.

>> No.813597
File: 2 KB, 568x194, notparallel.png [View same] [iqdb] [saucenao] [google]
813597

>>813589
Pretty sure it's wired like this.

>> No.813599

>>813579
Don't use a wire that's interrupted, use a pair of wires that the power moves between, like you'd see in a hallway lightswitch.

>> No.813607

>>813527
>>813552
I was more just wondering if it was written like "don't worry, this things won't melt until you hit it with 15 KVs, bro! Oh, you didn't want that current to hit your processor either? Well, shit."

Guess this works though. Thanks for the input guys. I'll buy a sheet and just cover the whole board with it since it won't act as a conductor. That way, I can isolate the board from the case without needing to secure it.

>> No.813685

I want to make a circuit that flashes an LED faster as the amplitude of an RF signal increases. I'm not sure what kind of IC I'd need to use to control the rate of flashing.

Also the input signal frequency will be on the order of 30GHz, which is way too fast to see, assuming an LED is even capable of switching that fast. So I need the output frequency to vary between something like 0-20Hz. How would I accomplish this?

>> No.813693

>>813685
It helps to split up a problem in sub-problems.
First you need an RF receiver.
Second you need to be able to measure the amplitude(strength) of an RF signal.
Don't map the led directly to the signal. convert the frequency to the lower value. I wouldn't know how so I'm going to shut up now

>> No.813715

>>806760
roll _

>> No.813744

Are you able to solder components onto perfboards that don't have copper around the hole? I've been trying to do it with a few components but I haven't been able to get a good joint.

>> No.813780

>>813607
>without needing to secure it.
If you make a rattle toy, there's always the risk that the sheet gets damaged at some point.
Secure the board someway.

>> No.813809

>>813333
Should I unwrap the material and see how the PCB is connected or is that inadvisable for any reason?

>> No.813810

I thought I could just plug 20 leds into a battery and it would just "work" until after asking someone expert I was shot down and made to realize that at most I can light up 3 leds with a 9v battery with a resistor.

Is there a way to light up a lot of leds with a 9v battery through the use of advanced circuitry? I think there probably is but I don't know where to even start looking

>> No.813811
File: 37 KB, 3000x1300, Untitled.png [View same] [iqdb] [saucenao] [google]
813811

>>813810
Connect them in parallel or series-parallel.
You can also try your luck with this: http://led.linear1.org/led.wiz
Pic related. That calculator has a tendency to make stupid suggestions, though.

>> No.813812
File: 39 KB, 637x276, 1431905224501.jpg [View same] [iqdb] [saucenao] [google]
813812

>>813810
https://www.youtube.com/watch?v=r7PYLRIphwg

>> No.813871

>>806660
Thanks OP for this. I've been trying to get into flat screen repair and found this thread a few weeks ago. I thought it was gone. But here you are, being great.

>> No.813878

>be me, today
>have exam, analogue circuits
>be off-books repeat student, complicating matters
>study this year's course, mostly anecdotal type stuff, describe the operation of an R-2R ladder, what is meant by the Q factor of an RLC, bias a CE amp etc.
>go to exam
>because off-books turns out I'm sitting paper based on last year's course, all in-depth transistor stuff, beta values and aspect ratios and transconductance
>remember literally 0% of last year's course

fuck


I'm sad now

>> No.813882

>>813878
Talk to your tutor immediately. When were you told what the content of your exam would be?

>> No.813887

>>813882

The situation is complicated. I had 3 exams this year, maths, signals & systems and analogue circuits. Originally I was under the impression that I'd be sitting exams from this year, since as far as I was concerned, and what I had been told, all off-books meant was that I didn't attend college and I wasn't marked for labs and tutorials, obviously. At that point I'd looked at the module pages for those subjects and saw that maths and signals and systems were the same as last year, analogue was different. So I studied the old maths and S&S courses and the new analogue course. Then the day before my first exam, maths, I found out that when I checked the module page it hadn't been updated, and the course had changed, the half of the paper which had been linear programming was now probability. I contacted my tutor and she said normally off-books people took a paper on the previous year course, but I would have had to contact the course coordinator, which nobody told me to do, and she said it was probably too late now. So I went and did maths, and it was based on the new probability course, but that went OK because it was pretty basic probability questions anyway. Since a previous-year exam hadn't been set for me for maths I thought it wouldn't be set for me for analogue either. But it was.

In the end it's all down to me not checking up on things enough, I don't think I have any grounds for appeal. At least supplemental exams are free.

>> No.813976

>>806760
Probably shit

>> No.814209
File: 123 KB, 2960x900, PSU.png [View same] [iqdb] [saucenao] [google]
814209

Hey /ohm/, how would I improve the transient response and noise of my benchtop power supply? I want to use it for my future projects so I want as little noise as possible if and when I do analog/audio stuff.

I already have a low pass filter on there and the transformer I have I salvaged, that's why I'm using a voltage doubler after the transformer. The transformer wasn't capable of putting out the 28 volts max I wanted by itself.

>> No.814224

>>814209
That ringing probably comes from your filter. Use a non-ideal inductor in simulation or add a damping resistor.
Add a capacitor to LM317's feedback pin. See the datasheet for details.
Voltage doubler goes against your noise goals.
Consider using a better regulator.

Also, design your audio stuff so that it isn't overly sensitive to power supply noise.

>> No.814237
File: 22 KB, 346x395, voltage-doubler-circuit-2-diode.jpg [View same] [iqdb] [saucenao] [google]
814237

>>814209

- your voltage doubler does not look like any doubler I've seen before
- it's a very bad idea to use a doubler in a power supply, for misc reasons
- your caps are pathetic. to get a reasonable current, you want to make the 220ufs and 100uF about 10x bigger.
- pic shows an actual doubler - dunno what yr circuit is doing, you're just putting 2 caps in parallel with 2 diodes
- you just get rid of the doubler and accept whatever output range you get until you find a proper 24Vac x-former.

>> No.814248
File: 9 KB, 300x255, Switcheable_rectifier.svg.png [View same] [iqdb] [saucenao] [google]
814248

>>814237
>your voltage doubler does not look like any doubler I've seen before
One of the first images on wikipedia for voltage multiplier is my circuit.
http://en.wikipedia.org/wiki/Rectifier#Voltage-multiplying_rectifiers

>-it's a very bad idea to use a doubler in a power supply, for misc reasons
I can't find a transformer that's the size I need, plus I won't be pulling much amperage from the thing so it should be fine.

>your caps are pathetic. to get a reasonable current, you want to make the 220ufs and 100uF about 10x bigger.
I'm not going to be pulling any more than 1 amps or so from the thing since my regulator is rated at 1.5 amps.

>>814224
>That ringing probably comes from your filter. Use a non-ideal inductor in simulation or add a damping resistor.
Alright I'll try that.

>Add a capacitor to LM317's feedback pin. See the datasheet for details.
C1 and C3 are the caps the datasheet suggested

>Voltage doubler goes against your noise goals.
Eh yeah true. I hate being poor or else I'd just buy the appropriate transformer.

>Consider using a better regulator.
If I can salvage one or buy one for dirt cheap I will.

>> No.814249

>>814224
>Voltage doubler goes against your noise goals
Oh another thing on that.
That's why I put the switch on there. That way I can turn off the voltage doubling when I need to.

>> No.814260

>>814248
>C1 and C3 are the caps the datasheet suggested
It also suggests using a third one on the adjustment pin.
The other anon is right, 220uF is small for 1A current.

>> No.814272

>>814260
What do you suggest then? There's no way the cap needs to be 10x bigger. I rarely see caps that big and my parts are 90% salvaged. I can't find equations on it. The caps I see in computer PSUs are usually between 400 to 600 uf

>> No.814281

>>814272
An old rule of thumb was 1uF per 1mA.
Some explanation: http://waynestegall.com/audio/ripple.htm
Also, your doubler runs at 50Hz, not 100Hz, and you have two capacitors in series -> you need 4 times bigger capacitors to achieve the same ripple level than with a normal diode bridge.

>> No.814295

>>814272
220uf for a 1A power supply? forget it. You are going to get a lot of ripple. Consider using a 2200uf capacitor, it will be a lot better and if you have the money, buy a 4700uf.

>I rarely see caps that big and my parts are 90% salvaged.

You don't see caps that big on the things you salvage because the things you salvage use switched power supply. Its rare to see devices that use linear power supply these days and that's why you don't see bigger caps. If you don't believe us, try it yourself, science is all about tests and discovery. Build your power supply with 220uf caps and see what happens when you get a 1A output current.

>> No.814502

>>807161
>>My question is, how would I go about making a game trainer for something like the 3DS or other handheld/console using an Attiny or Arduino?
There were some threads on /g/ a month ago about that, search for ROM Hacking on its archive. Those were great threads.

>> No.814621
File: 397 KB, 1485x1170, perfboard assembled by a monkey.jpg [View same] [iqdb] [saucenao] [google]
814621

>>813744
>Are you able to solder components onto perfboards that don't have copper around the hole? I've been trying to do it with a few components but I haven't been able to get a good joint.

I dont see why you cant just wrap some wire around the leads, it's so easy a monkey can do it. here is an example assembled by a lovely primate I know personally.

>> No.814742
File: 84 KB, 800x600, qm1500-1.jpg [View same] [iqdb] [saucenao] [google]
814742

I've got a dead monitor and wanted to test the different parts of the circuit to see what's gone wrong. I've already discharged all the capacitors.

I grabbed one of these shitty $10 multimeters because the nicer one I bought from china still didn't arrive after 2 months and them sending a second one so fuck that.

What setting do I want it on for testing things like capacitors and controllers on a circuit?

>> No.814749

>>814295
Alright, I found some 1000uf 50v caps in an old TV. They seem to work. I have at least 5, so I could put two in parallel at C4 then again at C2 upgrading those 220uf to 2000uf each.
Then I could put a 1000uf cap at C6 and upgrade C5 to 47uf.

Basically almost multiplying all my caps by 10.
I found some 2200uf capacitors but they're rated at only 25 volts and will get blown once I throw that doubler switch.
Otherwise, think those will be enough?
There's not really much I can do about the caps in series since those are required for the voltage doubler, unless I made one of the caps large and the other smaller. That might increase the overall capacitance.
So maybe have C4 at 3000uf with 3 caps and C2 at 1000uf?

Sorry, I'm still relatively new to this if it wasn't obvious.

>> No.814760

>>806760
Rollin,
Some of these look hilarious.

>> No.814763

>>813744
Not getting a good joint is usually down to not getting your wires clean and bright. Also use a good solder such as Multicore.

I usd to have special abrasive rubbers that were great for cleaning edge connectors and component leads - not sure where you can get them now.

Also made do wire fine wire wool to clean components - just clean them well away from where you solder - wire wool fragments and electronics are not a good mix.

>> No.814767

>>814742
mostly the diode mode. but if you dont have knowledge of the basics you shouldnt do something like this.

what kind of monitor is it?
look for blown fuses/capacicators/parts first

>> No.814770

>>814749

Yeah, two 1000uf in parallel in each side will be great, your total capacitance will be 1000uf when the doubler is not turned on. This is because when caps are in series, the capacitance decreases.

The other question is, do you really need a 28V power supply?
I have years working with amplifiers (op amp and transistors), RF circuits and I've used more than 20v on my symmetrical power supply (10V each side) just a few times for my projects.

What I suggest for you in this: build the power supply without the doubler, it will prevent lots of pain in the head for you. Just use the transformer you have and accept whatever output you get for now. In the future, you upgrade it with a new transformer when you have the money. If you need more output voltage, you can connect another power supply in series with yours. A 5V 2A mobile phone wall charger will do the work. Do not be afraid, connecting two power supplies is totally safe, just do not exceed the current of the power supply with least current, in this case yours with 1.5A output.

>> No.814778

>>814770
>you can connect another power supply in series with yours.
I didn't even think about that.
I have multiple transformers, all of them are around 12ish volts with load. I may see if I can use multiple transformers instead of a doubler to get the voltage I want.

24v is probably all I'll need. I'd just rather have more than I need and not need it than not have enough incase I do need it.

>> No.814783

>>814767
Samsung p2350. Backlight keeps turning itself off after being on for a second. Capacitors are all fine. Checked the backlight itself and it seems fine. Saw a forum post about the mosfets being shorted so want to check that. http://www.badcaps.net/forum/showthread.php?t=12944

>> No.814784
File: 133 KB, 2960x900, Linear PSU v2.png [View same] [iqdb] [saucenao] [google]
814784

>>814778
>>814770
Alright here's version 2.
I'm using two transformers instead of a voltage doubler, I increased my smoothing capacitor to 2000uf, and I also found out the transformers I have are 10:1 not 17:2. The only reason why I thought they were 17:2 was because I didn't realize transformers without load read a higher voltage than what they actually are. I thought these were 14v transformers, but they're 12v.

The ripple actually looks a lot better than it did beforehand.

>> No.814786

>>814778

There you go.
Now you can make two 12V power supply and make a symmetrical one. Just make the same project two times and if you want more than 12V just connect the negative of one in the positive of the other.

You have 4 x 1000uf capacitors, use 2 in each power supply.
You can salvage inductors from old pc power supplies, normally the 5V lane has a 100uH inductor. Its the one with a 0,75mm wire and 26~30 turns.

>> No.814787

>>814786
Is it better to make a symmetrical power supply rather than just wiring up the two transformers? I suppose it'd let me pull more amperage along with the higher supply voltage when I connect them, if it works that way with current too.

>> No.814793

>>814787
It's better to make two power supplies.When you connect two transformers like this, if the wire of one transformer is thinner than the other transformer, it will lead one of them to overheat.
And no, it would not let you pull more amperage because you are wiring the two transformer in series. The current will be the same in the two transformers and the maximum amperage will be the maximum amperage of the least powerful transformer.
That's another good point of making two power supplies. If you put a 0.33/5V resistor on the output of each one, you can connect them in parallel, doubling your amperage.

>> No.814794

>>814793

Sorry, I meant 0.33Ohm/5W and not 0.33/5V.

>> No.814810

>>814621
That's exactly what I tried doing but the bonding didn't go too well.
>>814763
I'm using the Lester brand after many recommendations. Is that good? Additionally, to clean wire, I just wipe the lead with the steel wool?

>> No.814819

>>813780
Fair enough.

Thanks for the input man, I'll work on securing the board.

>> No.814822

>>806660
Can someone explain why /ohm/ is so negative about commercial micro-controllers such as arduino?

>> No.814824

>>814822
it is just like hackaday comments, sour people that want to whine.

not everybody is a professional electronics designer, a lot of people just like messing around

>> No.814826

>>814822
its a $1 chip that they sell to chumps for $40 because it only works with their garbage ide.

>> No.814828 [DELETED] 

>>814822
Because micro controlers "kills" electronics. Please, note that I put "kill" between quotes.
By kill I mean that people wants to put a arduino every where. Simple projects like lighting up a led using a light sensor that would be easily solved with just one op amp, people want to use an arduino and dont even want to know there is another way to do it.

>> No.814836

>>814822
Because micro-controlers "kills" electronics. Please, note that I put "kill" between quotes marks.
By kill I mean that people wants to put a arduino every where. Simple projects like lighting up a led using a light sensor that would be easily solved with just one op amp, people want to use an arduino and dont even want to know there is another way to do it, making a project that would cost less than $3 cost $40 because of the Arduino. I know sometimes you really need to use it, sometimes there is no other way like in projects tha involves keypads, LCD displays. But even on these cases you can have cheaper micro-controler solutions like PIC (just YARR the compiler) or use a atmel that worth less than 3 dollars.

>> No.814843

>>806760
Might as well.

>> No.814845

>>806760
reroll

>> No.814880

>>814836
>>814826
>>814824
Got it.
>>814836
Is there any materials off which i could learn this type of stuff? Im first year in my higher education vocational engineering course and next year it expands into electrical part so i know how to operate with the basics such as AC calculations, transformers, op amps, magnets ect.

>> No.814885

>>814880

These 7 videos will get you started on op amp's world:

https://www.youtube.com/playlist?list=PLvOlSehNtuHu2FviAaZaiyXwN41G4b1Lf


This book is great:

The Art of Electronics by Paul Horowitz
(Just YAARRR the goddamn pdf, you dont need to pay $140 for the book.). I still use it even after I'm graduated from university.

>> No.814963

>>814885

>The Art of Electronics by Paul Horowitz
This, a million times this.
I highly recommend buying the book if you're serious about electronics.
If electronics had a holy text, this would be it.

>> No.815027

looking for a cheap AVR that can handle 2-3 analog outputs/inputs

is an atmega8 enough?

>> No.815032

>>814885
>>814963
TAoE works better as a reference for people who already know their shit. Practical Electronics for Inventors is a wayyyy better resource for someone who is starting out.

>> No.815043

>>815027
If you're going to use less than 6 I/O the Attiny85 is great, 1MHz using the internal clock and up to 20 with an external one. Works fine with voltages from 2.7 to 5.5, with an sleep mode that allows it to work on a few microamps. It's also quite popular and documented. For more I/O you can use the 2313.

>> No.815051

>>806760
Roll

>> No.815056
File: 127 KB, 720x1280, Screenshot_2015-05-21-03-31-27.png [View same] [iqdb] [saucenao] [google]
815056

>>806760
Bored, let's roll.

>> No.815235

>>814783
could be also a dead converter for the backlight.

i mostly just change the mainboard with problems like this because sometimes its a pain in the ass to find the right spareparts or even the faulty part

>> No.815241

Is it safe to not wash hands after touching solder joint s with lead?

>> No.815249

>>815241
Probably much safer than to walk under the sun. Lead is only 40%, touching them won't make lead stick to your fingers, trespass the skin barrier or anything like that. If you are constantly soldering, clipping, and filing lead and your fingertips have darkened consider to clean your hands before you touch something you are going to eat.

>> No.815338

>>806760
I'm up for this!

>> No.815341
File: 598 KB, 1920x2560, madstash.jpg [View same] [iqdb] [saucenao] [google]
815341

Sup /ohm/, sup Paraelectrical Plebeian (PP) threw this out, and I just happened to find it on the side of the road. Let's see what we found!

>> No.815343
File: 455 KB, 2560x1920, IMG_20150520_142451.jpg [View same] [iqdb] [saucenao] [google]
815343

What's this???

>> No.815344
File: 492 KB, 2560x1920, IMG_20150520_142516.jpg [View same] [iqdb] [saucenao] [google]
815344

ohhai :3

>> No.815346
File: 597 KB, 2560x1920, IMG_20150520_142641.jpg [View same] [iqdb] [saucenao] [google]
815346

This appears to be some standardized module, it only contains surface mounted parts. I could not get a decent grasp on what is it, I found some datasheets describing laser wavelenghts and such but what it is, I don't know

>> No.815347
File: 478 KB, 1920x2560, IMG_20150520_142718.jpg [View same] [iqdb] [saucenao] [google]
815347

oh well...

>> No.815349
File: 536 KB, 1920x2560, IMG_20150521_202629.jpg [View same] [iqdb] [saucenao] [google]
815349

This cute chip hanging on for it's dear life is a NEC PS2652. Datasheet sez it's an optocoupler, containing an internal led and a phototransistor, breddy cool
So that's it, free stuff.
I wonder what this device was before it was vandalized

>> No.815353

>>815347
Looks like the power supply of a monitor or TV.

>>815346
This is likely the part of a switching PSU that gives you the high frequency output.

>> No.815384

This is not really related to electronics, but I think it is the best place to ask: how hot can an immersion water heater get when it's not submerged in water? I'm asking this because I want to use it to turn wood into charcoal, and it should be able to heat up a reasonable amount of wood to >250°C.

>> No.815424

>>806660
Dont know if this is supose to be a general question thread, but Im sure someone here might be able to help.


I am going to be working on a project that reads serial data from a 12v source, but Ill the using a 5v device to read the data and possibly interact with the 12v device.

How should I go about dropping th 12v serial to 5v serial? is there a way to do it safely wtih resistors and diodes or am I going to have to find a voltage reg (like a 7805?)?

TLDR: have 12v serial and need 5v serial without buying stuff.

>> No.815431

>>815424
If you mean to say that you have a device using the standard RS-232 levels and you want to connect it to a 5V UART, then you need to invert the signal in addition to scaling it.

A transistor, couple of resistors and a semi-optional diode will do that. Or an IC like MAX232. Transistor inverters can be slow, so you might have problems at 115200bps or higher.

>> No.815439

>>815431
To be honest I dont know much about serial connections, but what I need is to have a way to read the codes from an obd 1.5 computer, at a baudrate of 8192. I dont know what standard the cars computer is using, the 5v device is uart though.

When you say invert the signal, what exactly do you mean?

>> No.815509

>>815424
>Dont know if this is supose to be a general question thread
See, that's what I've been saying all along: the whole /ohm/ thing is dumb and no-one understands what it's supposed to mean, and unlike /ak/ (which is also a pun) electronics has very little to do with /m/ and nothing to do with /o/ and /h/.

>> No.815512

>>815509
lolwut

>> No.815516

>>815439
>>815431
>how to convert 12v to 5v
You didn't say you were using it in a car. Cars' electrics are full of horrid noise; it would be an excellent idea to fully isolate your input.

You can do this with an optoisolator: inside is an LED shining on a photodiode. Because diodes are current-devices, they don't much care what voltage goes across them, so long as it's greater than their forward voltage.

To the car, you connect the LED side through a current-limiting resistor.

On the computer side you /supply/ the appropriate voltage, and connect it through the photodiode to the receive pin, with appropriate current-limiting and pullup/pulldown resistors.

Crap in the car's electrics can't reach the computer, because there is no electrical connection between them whatsoever.

Read the datasheets, and make sure you get one fast enough for the connection you're planning to run over it.

>> No.815520

>>815516
Ill pick up a fast optoisolater and see what happens, at first I just need to see if I can read anything from the car then go from there.
Im not going for a full car computer setup, its an obd 1.5 situation, cant use as most scan tools to see why the check engine light is on.

So do you think that if I were to (with current limiting) just hook the upto isolator up like this it would actually send meaningful data,
Car:
serial out -> resistor -> opto isolator -> ground
MCU: RX <- Opto isolator <- resistor <- 5v

>> No.815607

>>815424

you can use a transistor to level shift up or down. also, there are chips made for just that purpose (Rs-232 to TTL and vice versa), as used in old RS-232 computer ports, the MC1488 and MC1489. dunno if they're still available. If not, Maxim makes modern equivalents, check this page to see which one is appropriate: http://www.maximintegrated.com/en/datasheet/index.mvp/id/1798

the Maxim chips dont need +/- 12V supplies, unlike the MC148x chips.

>> No.815631

>>815509
The name is supposed to be "/ohm/ - electronics general" but the OP left off the second part in the subject.

I decided to name this general /ohm/ because it sounded better than /eg/ or /eeg/ or even worse: /egg/.

/ohm/ is a euphemism, not an acronym.

>> No.815663
File: 30 KB, 645x354, rs2324.jpg [View same] [iqdb] [saucenao] [google]
815663

>>815424
been using this on a couple of 8051 projects. highest speed i've used so far was 115200 baud with no problems. diode was a 1n4148 and transistors 2n2222 and 2n3904

>> No.815690

>>815631
It still suggests a board, which it isn't.

The whole idea of giving a general thread its own idiosyncratic identity is dumb: as you just saw, the people who stand most to benefit from general threads fail to recognise it as such.

>> No.815703

How would I design a circuit that has an LED turn on when a capacitor is fully charged?

I'm thinking it'd have to be in parallel since no current would flow through the cap once it is fully charged, however in parallel current would still split between the cap and LED.

What am I missing?

>> No.815704

>>815703
Maybe the fact that you need to compromise at least a bit about that "fully charged" state and turn on the indicator when the capacitor is not 100% charged.
You can detect either voltage or charging current. The latter would be independent of the charging voltage, but requires a resistor in series with the capacitor.
If you want that the indicator LED won't rob current from capacitor, you have to have a separate supply for it.

>> No.815706
File: 162 KB, 581x547, 767gu.jpg [View same] [iqdb] [saucenao] [google]
815706

>>815690
its a stupid /g/ thing that op wants to spread here.

>> No.815709

>>815704
So like a voltage dependant source for the LED linked to the cap voltage?

>> No.815711

>>815509
>>815631
>>815690
>>815706
it's easier to ctrl+f ohm than to search for electronics general or anything else like that. it's also usable with 4chan's search feature: https://boards.4chan.org/diy/ohm
it's useful to have an acronym or a pseuso-acronym for these threads, as it is constant, while the names of the threads might be altered slightly (stupid questions thread, stupid questions general, questions that don't deserve their own thread, etc). in fact I found this thread by searching ohm in the catalog.

>> No.815718

>>815703
The best way is to use an OP amp as a comparator and compare voltages using voltage dividers made with resistors. You can also use a zener if you want to charge the caps up to a determined voltage (e.g: 3.3, 5, 12...V), take into account if you add an LED in series the voltages would add up (e.g: white LED+5volt zener = 3.3+5)

If you parallel say a white LED with a capacitor the cap will charge up to 3.3 volts, when it reaches that voltage the LED should lit up. It's like having a pond and making a hole at a certain height, the water will flow out through the hole (the LED), not allowing the pond (the cap) to fill more.
If you do this, set a resistor to lomit the current going into the cap and resistor circuit, this will stop the LED from frying when the voltage is reached.

>> No.815722
File: 26 KB, 545x306, mosfet.jpg [View same] [iqdb] [saucenao] [google]
815722

How do I check mosfets are working with a DMM?

>> No.815723

>>815718
K I haven't had our class on diodes and what not yet so I'll look into those. Thanks my man. I didn't even think of using an op amp either.

Luv u, /ohm/

>> No.815725

>>815706
>implying /g/
It's everywhere

>> No.815726
File: 9 KB, 600x600, masterpiece.png [View same] [iqdb] [saucenao] [google]
815726

>>815709
Well, you could say so.
Pic related would be one (crude) way to do it. The LED turns on when the capacitor voltage is around 11V. This might actually need a shunt resistor from base to ground to produce reasonably sharp turn-on.
You can use fancier comparator circuits to reduce the current draw from capacitor even further, make the turn-on sharper and to get the threshold closer to full charge.

>> No.815727

>>806760
Roll

>> No.815734

>>815722
short gate to source
use the diode beeper on drain-source to see that there's a diode in one direction and nothing in the other direction
use the resistance measurement to see that the gate is isolated from everything else
use the resistance measurement to charge the gate (gate positive, source negative on nmos).
measure the drain-source resistance to see if the fet is now on
if not, tease the gate with your finger or a power supply to turn the fet on

Yeah, bit tedious and clumsy. Maybe someone else has a better method.

>> No.815814
File: 217 KB, 571x572, 2015-05-23_04-16-56.png [View same] [iqdb] [saucenao] [google]
815814

Does anyone with some SMD PCB design experience feel like auditing my board? This is my first layout attempt, I was going to start with some basic shit but tooling cost and lack of ideas made me put it off, so while I have done a lot of research I have probably made some retard level mistakes and I'd rather not have a completely useless board(I know i need to add some fucking test pads).

Let me know what the best format is to send it in. I'm using altium btw.

>> No.815816

>>815690
>The whole idea of giving a general thread its own idiosyncratic identity is dumb:

Not really, it helps people identify the general once they're involved in it.
Just like >>815711 said, I do the same thing to jump to the general. All you need to do is append "Electronics General" to the end of /ohm/ and you've solved all the confusion. Anyone who can't understand that "/ohm/ - Electronics General" means a general thread for electronics discussion probably shouldn't be here in the first place.

>> No.815819

>>815706
It's not a /g/ thing. It's a 4chan thing.
Every board does it, even other generals on this board.

>> No.815854

Where the torrents for art of electronics 3rd edition at tho?

>> No.815860

>>815854
Pdf version is coming out in June. Not sure exactly when though.

>> No.815864

>>815860
that would explain why noone has taken the time to scan it yet.

>> No.815885

>>815860
Fukin sweet

>> No.815893

>>815631
>/egg/
Made me giggle

>> No.815896

>>806760
Rowl

>> No.815916

>>806760
Wut is a plasma speaker

>> No.815928

>>815916
http://en.m.wikipedia.org/wiki/Plasma_speaker

>> No.815938

>>815690
>people who stand most to benefit from general threads fail to recognise it as such.

Its read as directly "ohm" and not as "o - h - m".
ohm and resistors are one of the fundamentals of electronics easily recognized even by people with little knowledge of electronics.

See:
http://archive.moe/diy/thread/698995/#q704783

>> No.815974

>>815938
>>815690
>>815706
>>815711
>>815816
>>815893

autism

>> No.815985

/mu/tant here (sorry is this isnt the place to ask)
has anyone here built their own synths? i have ~1 year of electrical experience, and was wondering if you guys ever built synths. ive built a simple Atari Punk with a 1/8th Input, and was wondering where to go next.
sorry again if this is the wrong place.

>> No.815988

>>815663
Ill give it a shot, thanks.

>>815607
if the above message messes up Ill look into that or an elm(numbers). Thanks

>> No.815989

>>815985
>ive built a simple Atari Punk with a 1/8th Input, and was wondering where to go next.

there are lots of places for synth design on the web. even entire web sites devoted to that old shit. Mr. Google knows where to find all those knob-fiddling losers, so ask him.

>> No.816001

>>815938
There's evidence of this happening, here, right-here, in this very thread.

You can't speculate or reason evidence away.

>> No.816002

>>816001
He would've asked the same thing no matter what the general was called.
"Not sure if this should go here" posts happen all the time, all across 4chan.
Serious question, how new are you?

>> No.816052

>>816001
It wasn't because the general is ALSO called /ohm/, but because OP forgot to put electronics general in the title, which is explained in the post chain you are replying to.
Noone will look at "/ohm/ - electronics general" and think "hmm, this is the elctronics general, but it's also called /ohm/, so maybe it's not an actual electronics general, even though it clearly says so in the title". But even if someone would, that's not enough reason to stop using it. That's like saying we should stop using memes, because some people don't get them on day one.

>> No.816056

>>816001
Regardless, complain all you like. /ohm/ is here to stay since it's been /ohm/ for several months now.
It's pretty much grandfathered in.

>> No.816064

>>816056
The thing he's complaining about is that this particular thread this time has no mention of "electronics" in its title, making it somewhat more difficult to find for those who are new on this board and would like to ask electronics related questions. Which is counterproductive.

You can have your /ohm/ in the title as well. You know, like "/ohm/ - electronics general", which has been the norm this far.

>> No.816106
File: 61 KB, 500x392, atari_punk01a.jpg [View same] [iqdb] [saucenao] [google]
816106

Why do my pots keep combusting? I wire center prong to input voltage, left prong to output(555), right prong grounded to bottom of pot.

I'm using a 9V battery in a simply circuit with a 1/2W 50Kohm pot. Do I need one with a higher watt resistance?

>> No.816122

>>816106
Yea try a higher power rating

>> No.816123

>>816106
Also, 555 timers generally run on 5 volts so put a 5V voltage regulator after the source

>> No.816258

>>816123
you need at least 5v for most of them, 18v is the limit but i've seen people running them on 50v unfiltered rectified AC and they don't explode.
>>816106
why not use a higher value like in the diagram?

>> No.816259

>>816258
>why not use a higher value like in the diagram?
wait never mind, can't actually read

>> No.816276

>>816258
Huh, didn't know that about the 555's. Should have checked muh datasheets

>> No.816281

>>816276
yeah, i say "most of them" because just about every chinamen and his dog still manufacturer them, so while the LM555 has these specs, you might find the clones catch fire at 9v or that they work fine down to 1.5v

>> No.816301
File: 5 KB, 542x390, multivibrador astable con 555.gif [View same] [iqdb] [saucenao] [google]
816301

>>816106

dont use a higher-wattage pot, your circuit is the problem. pin 7 of the 555 is used to discharge the timing cap. it does this by essentially shorting pint 7 to ground when appropriate. if your pot is at the min value, you're shorting it across the power supply which will cause it to burn. solution: put a fixed resistor in series, like 1K, which will limit the max current thru the pot to Vcc/1000.

this is one of those things that are often omitted from schematics coz it's assumed you know it. sucks if you dont.

>> No.816327

>>816301
>this is one of those things that are often omitted from schematics
fucking this, the amount of bullshit pseudo schematics around is outstanding. it seems linear is the only company still including application notes in there datasheets too.

>> No.816465

>>813594
>This
Also in this day and age scrapping for "free" bits and ends isnt worth the hassle.
Unless youre using it to practice your desoldering skills and finesse with the iron.

>> No.816468

>>814836
To be fair arduinos pro mini are $1.80 with free int shipping on Aliexpress.

>> No.816469

>>815343
If you dont know what a capacitor is or how to discharge it properly, you shouldnt be messing with it.

>> No.816571

>>814836
I see your point overall but on the subject of micro-controllers arduino clones for nanos and minies are very cheap now, < $3, so in terms of cost effectiveness that's not really an argument anymore. The cost factor is what made me reconsider my PIC snobbery.

I mean yeah I can still get a 12f683 for less than $1 and pound out some assembly when I need a little 8 pin device for a project, but when you start needing more I/o and the choice is between a $2 16pin pic and a $2.5 arduino complete with arduino's really handy hardware library and free decent implementation of C, then, if productivity is your concern instead of instruction cycle efficiency you have to go with the arduino.

Also as a hobbiest in a rural area I have no day to day contact with other builders except online and PIC guys online seem to either be more professional or maybe have a more independent approach toward problem solving so no one gives a shit about your code. At least when you create some cool software library on an arduino someone gives a shit enough to reuse it. I like that validation.

>> No.816741

>>816469
lmoawhat the point of that image was the n channel mosfet under that sheath
>implying I don't know how to discharge a capacitor

>> No.816799
File: 3.21 MB, 390x293, 1432322831542.gif [View same] [iqdb] [saucenao] [google]
816799

>>816259
wot.
I meant to write 500Kohm. Yet they still burn.
>>816281
This is very true.
>>816301
>>816327
Seriously? Wow I would have never figured. Thank you. I'm going to try yours in the next couple days. Having a pot in front of the voltage divider makes a lot of sense.

>> No.817231

>>806760
Alright, I'm a total newbie to /ohm/.

I don't really need an outright answer, but can someone give me a vague idea on how to build a LED Cube Equalizer without a microcontroller?

Or, pretty much any equalizer without a microcontroller for that matter.

>> No.817241

>LED Cube Equalizer

first step is to call it the right name. it's a spectrum analyzer. an equalizer is something completely different. now go forth and google.