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Two stupid newbie questions: I have an 8x8 LED matrix, specifically this one. The example they link to (on arduino.cc) doesn't show any current limiting resistors though. Do the LEDs in the matrix have some internal current limiting, or am I missing something here? Second, a 74HC595 (8 bit shift register) can only pass about 70mA total. If using it to control 8 LEDs you have to limit each one to about 9mA and they'll be quite dim. You can use a transistor for each LED, but is there a way to do it with fewer components?
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Jan 30, 2015 13:22
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Parallel Paraplegic posted:That's like my favorite part about electronics. "Hmm that thing I randomly saw looks useful, might as well buy 10 of them for $0.05 each!" 
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Feb 4, 2015 00:19
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Salvaged some components from a 90s era voice logging machine at work that we were scrapping. Some pots, a rotary encoder, and this thing: It's a 320x256 EL display, which are apparently still sold and cost $600.  According to the datasheet it's got a really simple interface, so I'll see if I can hook it up to an arduino and draw a dick on it or something. Collateral Damage fucked around with this message at 20:53 on Feb 12, 2015 |
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Feb 12, 2015 20:51
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When I come across long winded videos that I still want to watch without skipping around I use the Youtube playback speed control. Most people are still perfectly understandable at double speed if you can stand the chipmunk voice they end up with.
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May 26, 2015 08:23
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Jonad posted:What's the best way for me to give myself lead poisoning, electronics thread?
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May 30, 2015 12:36
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Parts Kit posted:You might be surprised. For instance, radioactive antiques are very much a thing.
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Jul 12, 2015 17:26
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I always get nervous when something doesn't work as expected but gets warm cause it usually means a short circuit somewhere. 
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Sep 7, 2015 16:17
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You could just grab a length of Cat5 which is cheap and will be good enough for most low voltage applications, and you get 8 conductors to play with.
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Sep 13, 2015 09:29
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And another notch for the "the weirdest problems have the simplest causes" theory.
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Oct 24, 2015 07:29
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General_Failure posted:May I ask something else? Can someone point me in the direction of a thread to ask about Arduinos? I've always built everything from scratch and have been resistant to buying a prefab uC solution. But I think it's time. I'm prepared to buy an Arduino knockoff from Aliexpress
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Jan 12, 2016 18:06
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There are a couple out-of-the-box USB-HID boards that you just hook up whatever buttons/levers/controllers you want to, for example http://www.leobodnar.com/products/BU0836/ Google for "usb game controller board" should find you a couple of other options. Alternatively some of the Arduino boards (Due and Leonardo at least, possibly others) can be used as a USB-HID device, which would allow you to do stuff like macro programming as well.
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Feb 9, 2016 15:39
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huhu posted:I'm designing a PCB that has 12 push buttons on it and I'd like each one to individually be able to trigger an LED when pressed, additionally they supply information to a Raspberry Pi or Arduino. My two ideas thus far were to have a wire from each button go to the LED but this would require 12 diodes, or have the LED wired up so that 5V > LED > all the push buttons > 220 resistor for each button > ground, but was told that the voltage drop across the LED might not cause the buttons to be triggered when pressed. My third thought was some kind of thing that receives all 12 push buttons and if any of its inputs are high, it'll output a high. I'm not sure if such a thing exists or if you guys have any other ideas.
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Jul 26, 2016 09:43
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ekuNNN posted:Yes, 670 to be exact. They don't have to do any hard work or anything though. I plan to control them by daisy-chaining 42 of these boards: https://www.adafruit.com/products/815
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Sep 9, 2016 20:18
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ekuNNN posted:We're basically making a screen out of servos. White pixels are servos in one position, Black pixels servos in another position. It doesnt Have to be controlled by a single controller, but the less controllers I have to buy the better. e: And if you have to custom build it, as PP said if you're only using two absolute positions anyway, solenoids are going to be a much better solution than servos. Collateral Damage fucked around with this message at 23:55 on Sep 9, 2016 |
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Sep 9, 2016 23:47
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Platystemon posted:I have a device I’m wiring to run off two power sources. One is a linear voltage regulator with +5.2 V output, and when that cuts out, as happens regularly, it needs battery backing.
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Sep 28, 2016 23:39
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Just have a 24-12v step down circuit to feed your lower voltage stuff. It's small and cheap if you don't need it to handle lots of current.
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Oct 19, 2016 19:27
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That's an awesome project ekuNNN, and now I understand why you needed so many. How did you solve the servo controlling? Did you daisy chain a whole bunch of control boards, or end up with some bus solution?
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Nov 3, 2016 15:17
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Yeah that's a good idea, I know they like to showcase cool stuff being done with their boards.
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Nov 3, 2016 16:51
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Private video?
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Nov 18, 2016 18:38
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johnnyonetime posted:Aside from just stringing more and more extension cords out there is there a better solution we can implement that could handle the load of all the light strings and possible go across one plug? Maybe like a high wattage power supply in the garage that runs out to the front yard? Sorry if this is an idiotic question, it's not the sort of thing I can just plug into google and get a decent answer. The faded strands are probably due to moisture/corrosion or a failing power supply rather than insufficient mains power.
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Dec 1, 2016 13:45
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Well that's one hell of a dumpster find. https://www.youtube.com/watch?v=d_S9YsD9Y0c
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Apr 1, 2017 22:32
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Cumslut1895 posted:Poor baby doesn't want a spider phone 
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May 8, 2017 09:33
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I have a pair of Argon 6340A active speakers for my PC which have some garbage "energy saving" feature where they'll shut themselves off if there's no sound input. The problem is the input detection is way too insensitive and even though the manual says they'll shut off after 20 minutes, they often shut off after ~30 seconds if the input volume drops too low, like during a quiet part of a song or game. It's pissing me off and I want it gone. I haven't cracked the speakers open yet, but there's an audible click when they turn off and on, so I'm assuming there's a mechanical relay that just cuts power to the amplifier. I figure if I can get to it, I can just bypass the relay to have the speakers active all the time. They still have a power switch in the rear to manually turn them off if needed. Alternatively I had the idea that I could run a USB lead from the computer to the speakers and use the power from the USB port to activate the relay so they'll stay active as long as the computer is on, but turn off when I turn the computer off. Without knowing the exact specs of the relay yet, do you think this would be a reasonable approach? Collateral Damage fucked around with this message at 11:12 on Jun 20, 2017 |
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Jun 20, 2017 11:09
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Nah, it's a pretty distinct click, not the pop you get when you turn a poorly made amplifier off.KnifeWrench posted:You have the switch in the back if you're concerned with draw while the computer is off. Using a relay as a wire is silly and wasteful. Collateral Damage fucked around with this message at 14:56 on Jun 20, 2017 |
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Jun 20, 2017 14:54
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So I cracked the speakers open to have a look. This is the main transformer. Power comes in on the left, the power switch is on the right with an inline fuse after the switch.  This is the relay board. There's a relay in the top left, but the back of the board is all epoxied over so I can't just short it out. So my new plan is to just bypass the board completely. The 4-pin connector at the bottom goes to the signal board. The 2 pin connector goes to the power LED, but I had to disconnect it to get the board out of the case.  I'm thinking this board doesn't do 220V rectifying, right? So I'm not sending AC into a tranformer that expects DC by shorting over the two connectors? The small transformer on the relay board outputs 11V AC and I assume it does low voltage rectifying to feed the input detection and power LED. Collateral Damage fucked around with this message at 18:26 on Jun 25, 2017 |
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Jun 25, 2017 14:33
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The 4-pin connector was glued in place so I just cut it off. Now the speakers are always on unless I decide to switch them off. Only drawback is the power LED doesn't work any more, but I can live with that. Screw your energy saving regulations. We have nuclear.  
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Jun 25, 2017 18:26
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ate all the Oreos posted:So my "scroll wheels in a box" project has evolved into trying to make a simpler, cheaper version of this overpriced bullshit:
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Jun 26, 2017 16:05
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Sagebrush posted:You might need a port expander or one of the bigger Arduino models (Mega) if you have a lot of candles and buttons, since you need one pin for each LED and each button, and a basic UNO only has 19 I/O pins. But the programming logic is pretty trivial -- something like this should do what you want, if I'm picturing it correctly:
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Jul 20, 2017 10:28
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Sockser posted:Yeah, that's what I assumed is what did it. I think I maybe put that jumper there (while shitfaced) to power the strips directly off the Teensy while I was debugging stuff and then didn't pay any attention to it when I shoved a 5v supply into the other side.
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Dec 29, 2017 10:08
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Historical reasons I bet. And with bands you don't have to care about mounting your resistor with the number facing up.
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Sep 2, 2018 13:31
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 Lead is dangerous? Hold my cigar.https://www.youtube.com/watch?v=jQ_85fp1avs
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Sep 28, 2018 22:26
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csammis posted:Soldering jobs, coding jobs, drawing jobs, construction jobs, cooking jobs… It happens way too often.
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Jan 19, 2023 11:13
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I have a TS101 and from what I've read it's basically the same as the Pinecil at a $10 or so premium, not enough to matter. Just go with whichever you can buy with the least amount of jumping through hoops.
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Dec 26, 2023 23:29
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Oh yeah I should mention the TS101 came with a very nice and flexible silicone USB-C cable, so all you need is a 45W+ USB-PD power supply. If you have an android phone made in the past two years you probably have one already.
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Dec 26, 2023 23:37
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I wonder if it would be enough to power something like a wireless keyboard or mouse. Would be nice to never have to charge that again.
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Apr 14, 2024 14:05
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| # ¿ May 5, 2024 18:52 |
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I built a custom wireless board a while back using a nice!nano controller (basically an Arduino Micro with a built in BLE module). It's powered by a 130mAh battery and a charge is good for about two weeks of daily use.
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Apr 14, 2024 16:25
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