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I backed a Kickstarter project for a remote controlled LED light stick. After a few uses it won't take a charge anymore. It looks like the creators have vanished so no refund. I'm a little surprised in all the comments on Kickstarter that someone hasn't been able to figure out the charging issue. I've never troubleshot a circuit that wasn't my own. How likely will I have any luck diagnosing the issue and fixing it?
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Jan 5, 2021 05:22
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Post pictures edit: do you have a scope? Close to zero chance if not Although if you have a multimeter and the battery voltage is below 2.8v, just replace it with a new battery every two years when their lovely circuit kills it
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Jan 5, 2021 05:53
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Even if you figured it out, you probably can't fix it if they hosed up the charging circuit.
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Jan 5, 2021 06:04
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Whether it's debuggable depends on a lot. It's a kickstarter so it's not going to be some high-volume impossible-to-fix custom IC thing. It's probably going to be a 2-layer board too which makes for easy reverse-engineering from board shot to schematic if it gets to that point. Has anybody shared schematics? If not, has anybody at least identified the parts on the board? That should be enough to decide whether it's worthwhile to try fixing. If they rolled their own charging circuit using a microcontroller or something, it's probably e-waste now, and was when it was first built too. If it's a well-designed battery controller used according to the datasheet maybe it was just a bad batch of LiPos. Speaking of lithium batteries, they tend to fail spectacularly and energetically, so if you have a product that is potentially damaging them treat it with due respect, since it may be a house fire waiting to happen.
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Jan 5, 2021 06:13
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A couple weeks ago my wife and I got into an argument with our roommate over whether or not wall warts are called wall warts. She thought we were making that term up to mess with her cuz she'd never heard it before, but couldn't think of what to call them other than that. Anyway I was reminded of that because I'm currently reading a datasheet and apparently the official name according to Microchip is:  REGULATED WALL CUBE e: I also just noticed that the REGULATED WALL CUBE picture is clearly a dirty, kinda blurry photocopy of I assume a much older datasheet that they just awkwardly pasted into the otherwise crisp new circuit diagram 
Shame Boy fucked around with this message at 20:20 on Jan 5, 2021 |
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Jan 5, 2021 20:17
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I've literally never heard them called that outside the electronics industry. Usually "cell phone chargers" are probably the most likely to be recognised
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Jan 5, 2021 20:22
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For my backpack PC, I have 36v ebike battery (18650 cells which are 10s5p, with balancing BMS) which goes to a 36v-to-12v50a DC-DC converter and powers the whole PC and GPU with that 12v50a The battery has two input/output on it. When I want to run it at my desk instead of on my back, could I plug the other side of the battery in to this "HEP-600-36" 36v power supply and leave it like that?: https://www.meanwell.com/webapp/product/search.aspx?prod=HEP-600 The power supply allows me to adjust the amps from 8-16 via potentiometer. I assume if there's always 36v being applied to the battery at a current that keeps up with average power use, the cells would tend to stay nominal at 3.6v each? If the cells are staying cool is there anything else I should be concerned about? I'm just wondering if there's some anomaly that could cause a single cell to become overvolted faster than the BMS can balance it and hit 5 volts and explode, or something.
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Jan 5, 2021 20:43
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Shame Boy posted:A couple weeks ago my wife and I got into an argument with our roommate over whether or not wall warts are called wall warts. She thought we were making that term up to mess with her cuz she'd never heard it before, but couldn't think of what to call them other than that. They are wallwarts, but knowing that they are called that makes you a huge nerd.
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Jan 5, 2021 20:53
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ante posted:I've literally never heard them called that outside the electronics industry. i heard “wall dongle” once and i’ve used it ever since. not strictly accurate but the word “dongle” is a perennial crowd-pleaser
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Jan 5, 2021 20:55
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Zero VGS posted:For my backpack PC, I have 36v ebike battery (18650 cells which are 10s5p, with balancing BMS) which goes to a 36v-to-12v50a DC-DC converter and powers the whole PC and GPU with that 12v50a So first of all, your battery system is a black box and using it in any way other than the manufacturer recommend way has some chance of loving with the circuit that they have designed. Lithium is scary. That said, your strategy sounds like it should work. The risk with a constant voltage supply is that it will provide too much current and heat up the cells (or the balancing circuit) and make them explode, but it sounds like you're aware of that. Your power supply also has current limiting features, and if you turn it way down, then your supply will switch into constant current mode and hold at that current (and be less than 36v for that duration) until it starts drawing less current and switches back over into constant voltage mode. Assuming that limit is 8A, and your batteries can also take 8A continuous, that should also be fine. So yes, grain of salt, but it passes the smell test for me, and it sounds like you are also aware of the potential issues.
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Jan 5, 2021 20:55
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Of course, there's also the wall wart's danglier & bulkier sibling: the line lump.
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Jan 5, 2021 21:25
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ynohtna posted:Of course, there's also the wall wart's danglier & bulkier sibling: the line lump. Or the catchall term "[power] brick"
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Jan 5, 2021 21:55
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AC/DC Wall Adapter is what it gets called in electronics catalogs
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Jan 5, 2021 22:01
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To me those things are variously AC adapters (most commonly), power bricks, power thingies, wall plug thingies, or transformers. I use the latter less often these day because most of the supplies are switching now and I'm  I know that wall wart is common but I don't like the sound of it.
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Jan 5, 2021 22:15
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Sagebrush posted:To me those things are variously AC adapters (most commonly), power bricks, power thingies, wall plug thingies, or transformers. I use the latter less often these day because most of the supplies are switching now and I'm I only use it when I'm explicitly looking for or referring to one in a collection of similar things, because most of the other terms aren't specific to "AC adapter where the circuitry is in a box that is also the plug housing" and can apply to the in-line boxes etc. Like this all came up because roommate asked what thing she needed to unplug to move something, and I was like "oh the wall wart", since it was plugged in to a power strip along with a few other things including some in-line box AC adapters. Also pretty much all wall-connected switching supplies still have a transformer in them, at the very least to get isolation, but I guess they're not only a transformer sure.
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Jan 5, 2021 23:14
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Shame Boy posted:A couple weeks ago my wife and I got into an argument with our roommate over whether or not wall warts are called wall warts. She thought we were making that term up to mess with her cuz she'd never heard it before, but couldn't think of what to call them other than that. Whenever I’ve introduced anyone to the term wall wart things have gone surprisingly similar.
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Jan 6, 2021 00:36
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Surely Google fixes any family argument in seconds?
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Jan 6, 2021 00:54
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thehustler posted:Surely Google fixes any family argument in seconds? any good family spat is a small part of a much larger decades-long power struggle. rookie move to get bogged down in the weeds of "who's empirically correct"
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Jan 6, 2021 02:11
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REGULATED WALL TRAPEZOIDAL PRISM according to that picture
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Jan 6, 2021 05:04
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Zero VGS posted:For my backpack PC, I have 36v ebike battery (18650 cells which are 10s5p, with balancing BMS) which goes to a 36v-to-12v50a DC-DC converter and powers the whole PC and GPU with that 12v50a Lithium batteries really hate being kept at constant voltage long-term, especially since you'll usually have them higher than 3.6v each so in this case the power supply will try and discharge them. You really want some kind of changeover circuit to toggle between battery and PSU -- or, instead, a 12v 30A Meanwell supply on the low-end. That will be much safer to just hork onto the line and let fly.
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Jan 6, 2021 16:42
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I've got a bunch of holiday lights that run on batteries, but I want to convert them all to wall power for next year. I have a little bit of hobby electronics experience from a few years ago. Is there a more to it than a 5VDC brick and a big resistor?
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Jan 6, 2021 16:49
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dupersaurus posted:I've got a bunch of holiday lights that run on batteries, but I want to convert them all to wall power for next year. I have a little bit of hobby electronics experience from a few years ago. Is there a more to it than a 5VDC brick and a big resistor? Speaking as someone who's done this several times cuz my wife likes using those LED wire sets as nightlights: nah that's about it. Personally I cut off the end of a USB cable to use, so I can just plug it in to a USB wall charger since I have a million of those and I assume everyone does. If you don't care if the LED's are super bright you don't even need that big a resistor. I'm using normal-rear end quarter watt resistors for all of mine and they barely even get warm, but they're only passing ~10mA. At this current the LED's are still pretty visible and definitely bright enough as an accent. e: Keep in mind if you wanna run your LED's much higher than this current, the resistor will start to heat up (regardless of the power rating, I mean the power still has to go somewhere) so you'll need to make sure you mount it where air can flow around it. Not at all hard to do since christmas lights are generally free-hanging wires, but I figured worth mentioning. Shame Boy fucked around with this message at 17:12 on Jan 6, 2021 |
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Jan 6, 2021 17:08
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If you're just hooking up a DC wall adapter up to the same electrical point where the battery hooks up, do you even need the resistor? Wouldn't the lights already have that to work with the battery anyway? Hell, there's a good chance the battery can dump more current than a random DC adapter can. Edit: Looked up a AA alkaline and they can only do 50mA constant apparently. So my bad, they do provide far less current if that's what it is. I'm used to Li-Ions. Forseti fucked around with this message at 17:29 on Jan 6, 2021 |
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Jan 6, 2021 17:26
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Forseti posted:If you're just hooking up a DC wall adapter up to the same electrical point where the battery hooks up, do you even need the resistor? Wouldn't the lights already have that to work with the battery anyway? Hell, there's a good chance the battery can dump more current than a random DC adapter can. Yeah, AAs. Although I hadn't thought about using USB, the adapters I was looking at are like 5V 2A, vanilla USB is like 0.5A right?
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Jan 6, 2021 17:35
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Yeah, 500mA is the max you get from a USB port without doing any trickery. Most will do 1000mA if you put a small resistor across the data lines (this is how it knows the device supports this "standard"). If you don't put a resistor across them it's not supposed to give you more than 500mA but I wouldn't bet that you couldn't find one that does so I wouldn't count on that without verifying. The really high power modes require communication with the controller on the other end afaik (although I really only am somewhat familiar with QuickCharge 2 and 3).
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Jan 6, 2021 17:40
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LED lights powered by e.g. CR2032 coil cells usually need a resistor added since they rely on the battery ESR to limit the current.
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Jan 6, 2021 17:42
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was doing research for a custom Kerbal Space Program console i'm designing and i ran into this extremely cool labour of love someone's working on. the highlights- uses a bunch of actual aircraft instrumentation, inc. a legit FDAI/navball; a bunch of scratchbuilt analog displays to emulate the precise Apollo command module instrumentation scheme, including at least one scratchbuilt tape meter (the readouts are printed on a long flexible reel that runs between two spool) that looks like a nightmare to fine-tune; and, especially for this thread, he's handling the LCD character decoding with flywire diode matrix ROMs, just like they would have back in the day    https://forum.kerbalspaceprogram.com/index.php?/topic/156435-kerbal-instrument-panel-in-desk-apollo-themed-hardware-controller/ First post has the instrumentation, about halfway down the first page are the flywire diode ROMs
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Jan 6, 2021 22:59
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dupersaurus posted:Yeah, AAs. Although I hadn't thought about using USB, the adapters I was looking at are like 5V 2A, vanilla USB is like 0.5A right? Yeah you're absolutely not gonna need two amps, though quite a lot of USB chargers can do over 2A these days even without any of the quick charge things. The LED string isn't gonna need more than 10-50mA anyway, unless you plan to run a bunch of them in parallel off a single jack or something. Forseti posted:If you're just hooking up a DC wall adapter up to the same electrical point where the battery hooks up, do you even need the resistor? Wouldn't the lights already have that to work with the battery anyway? Hell, there's a good chance the battery can dump more current than a random DC adapter can. In every one of the battery-powered LED strings I've taken apart, the battery box has a resistor inside next to the switch, cuz yeah you don't want to just dump the full battery current across the LED's. You gotta swap it out for a higher valued one regardless though since you're going from 3V battery to 5V USB.
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Jan 6, 2021 23:15
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Forseti posted:If you're just hooking up a DC wall adapter up to the same electrical point where the battery hooks up, do you even need the resistor? Wouldn't the lights already have that to work with the battery anyway? Hell, there's a good chance the battery can dump more current than a random DC adapter can. AA batteries will do a few amps for a few seconds. More than enough to burn up an LED.
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Jan 7, 2021 06:24
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Does anyone know where to get those linear guide rails / servos that you use in a Flying Probe / AOI machine? I can't figure out how to get something high speed, there's plenty of them for like.. standing desks. e: I know the standard ‘square x’ rails and the belt-driven carts, but is there a high-precision option? PRADA SLUT fucked around with this message at 09:00 on Jan 7, 2021 |
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Jan 7, 2021 07:30
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Ambrose Burnside posted:https://forum.kerbalspaceprogram.com/index.php?/topic/156435-kerbal-instrument-panel-in-desk-apollo-themed-hardware-controller/ Pretty cool, thanks for sharing it
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Jan 7, 2021 09:29
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PRADA SLUT posted:Does anyone know where to get those linear guide rails / servos that you use in a Flying Probe / AOI machine? I can't figure out how to get something high speed, there's plenty of them for like.. standing desks. McMaster Carr probably has them but I am not skilled at navigating their massive catalog. The 3D Printer is probably a good place to ask too if nobody here knows
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Jan 7, 2021 15:28
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PRADA SLUT posted:Does anyone know where to get those linear guide rails / servos that you use in a Flying Probe / AOI machine? I can't figure out how to get something high speed, there's plenty of them for like.. standing desks. Go play around on igus.com
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Jan 7, 2021 15:44
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This is a vague question, but are there any gotchas with I2C config? For example, SPI might only work if configured with a certain phase, and polarity, with different devices have different requirements. I'm struggling getting the MLX90614 IR thermometer to work. - Works on Raspberry Pi - Doesn't work on STM32. Have tried L4 and F3 dev boards. No commands work; no signs of life. I'm using the same drivers as with the Pi. - Other I2C devices on the same line (eg a display) work - Have tried I2C clock speeds from 10kHz - 100kHz - I've eliminated wire issues; ie I've used the same wires on the Pi and STM32 boards. It's described as using 3V, while the lines it's connected to are notionally 3.3V. Could this be a problem? How would you troubleshoot? Use an oscilloscope? Could it be that it's SMBUS instead of I2C be an issue? The Ref Manual states the line I'm using is SMBUS compatible. Thank you. Dominoes fucked around with this message at 03:40 on Jan 8, 2021 |
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Jan 8, 2021 03:26
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Is the bus terminated? https://www.i2c-bus.org/termination/ Edit: To expand, I don't know off the top of my head, is the Pi 5V and the STM32 3.3V? There's a rise time on your bus that depends on its capacitance and the pull up resistors. 5V will rise faster Forseti fucked around with this message at 03:59 on Jan 8, 2021 |
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Jan 8, 2021 03:55
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Look up "clock stretching", that's a fun one https://www.i2c-bus.org/clock-stretching/ Also, you have a pull-up resistor at each pin at each peripheral device? Do you have a logic analyser? One of the best $10 you'll ever spend, if you don't
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Jan 8, 2021 03:59
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Forseti posted:Is the bus terminated? https://www.i2c-bus.org/termination/  .ante posted:Look up "clock stretching", that's a fun one I noticed there are a few SMBUS-related bits on the STM32 I2C control register. Tried setting them, but still doesn't work. I suspect that would also have kept it from working.
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Jan 8, 2021 04:06
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Dominoes posted:How would you troubleshoot? Use an oscilloscope? Could it be that it's SMBUS instead of I2C be an issue? The Ref Manual states the line I'm using is SMBUS compatible. Thank you.
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Jan 8, 2021 04:08
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Yeah a logic analyzer should answers really really fast. Usually it's something with pull-ups, weird ACK bit, address conflict, or something like that. Or maybe the STM32 peripheral isn't actually configuring the I/Os and they are stuck as push-pull or something like that.
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Jan 8, 2021 04:33
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Also, programming whatever dev board you have with the Arduino standard I2C scanner sketch will rule out any hardware issues
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Jan 8, 2021 04:33
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