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Through a comedy of errors, I managed to smoke a Pi Zero W, which thankfully there is stock for. Here's a gentle reminder to color code your 5V power supply wires. That CPU gets REAL hot when I plug it in now. I was thinking good thing I didn't do this to my Pi 2 or 3, but apparently those actually are protected against this.
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Sep 22, 2021 10:12
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His Divine Shadow posted:Speaking of components, does anyone know what this is? Well 471 on a capacitor would indicate 470 pF. It could be a dual capacitor.
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Oct 24, 2021 21:19
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Strange question, but we have an old fiber optic desktop xmas tree that uses a small weird 12VAC motor to spin a color wheel in front of a lightbulb. The motor burned out and I got a replacement, but it is 5rpm vs the original which was about 2rpm. Is there a way to limit that speed without lowering the voltage to the bulb? Would something as simple as wiring them in parallel and just a resistor on the motor leg work? This is assuming it can even run with voltage under 12vac. Simplist solution would of course be a 6vac wall wort, but the bulb is non dimmable. Motor is listed as 1-2W. Bulb is 10W.
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Dec 13, 2021 22:14
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Stack Machine posted:Yep. You have the right idea. 2W at 12V works out to 1/6 of an Ampere so if you put a few 5.6-ohm quarter-watt resistors in series each will drop about 1V and burn about 1/6W. You can just keep adding these until it's slow enough. Those resistors all together will get a little warm, but not as warm as a 10W incandescent bulb so if you can find a place near that to put it, it's probably fine. This worked incredibly well for dropping the voltage, but today I learned a synchronous motor is a thing. Using that term I ended up finding a 1rpm motor which should be perfect.
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Dec 14, 2021 10:25
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Foxfire_ posted:A fx-888d is about $100 and is a perfectly cromulant entry level iron that has accurate heat control and won't fall apart I use this one and it's great for everything I do from auto stuff, to 3d printers, to small wiring for poo poo like my headtracker point model. I have a bunch of tips but 99% of the time I just leave the chisel on it.
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Dec 29, 2021 04:18
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Gromit posted:A friend asked me to take a look at her cheap rechargeable headphones, as she didn't know if it was an issue with the dock or the battery stopping it from charging. I know poo poo all, but can use a screwdriver and check for bad capacitors or anything easy like that. Same size will be fine. The only thing that will change with size is the capacity, but batteries like that will all be in the same ballpark. That one linked should be fine. When peeling the tape off make sure not to rip the battery open. Also maybe do it outside and above something you can just drop the fuming hot battery into. I'm curious why it swelled though, how old is it?
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Jan 28, 2022 02:41
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Is there a combo 5v Boost/Lipo Charge board that doesn't have a 50mA low output cutoff or cost $15? I'm using an Arduino with a small LCD screen and to get it to stay on I had to use a load resistor and I'm using waaaay more power keeping the board on than what the Arduino + LCD even use. 100ohm wasn't enough so I ended up using 2 150ohm resistors in parallel which did the trick. I tried wiring the key to a pin, but unfortunately that means you have to trigger the pin first to even get the board to boot. So I would need to add a button for it in addition to my on off switch and I don't really want to shoehorn that into the case. The only one I'm finding is this, but at $16 it costs more than everything else in the project combined: https://www.sparkfun.com/products/14411
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Feb 7, 2022 10:09
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longview posted:I guess the solutions you've tried are meant for USB battery bank applications, hence the shutoff feature? Yeah, in this case it's an 18650 powering a thermistor, Arduino, and LCD for reading temps up to about 300c. I was hoping to shrink the battery since with this it could literally run for days, but I might just pick one of those single 18650 boards up and use that. The board I have supports power passthough, but it's hilarious that the trigger delay from disconnecting the wallwart power is so long that whatever you have hooked up shuts down before the backup kicks in.
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Feb 7, 2022 19:19
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I just have my windows open and a fan blowing at me. How much am I gonna regret that in 20 years?
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Feb 9, 2022 01:23
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Good to know! My fan gets to keep its place on the desk..For now.
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Feb 9, 2022 01:58
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PDP-1 posted:I have a Hakko FA-400 (pic below) and it's... OK I guess. It has to be pretty close to where the soldering is happening to suck up the smoke efficiently. In retrospect I would have preferred one of the models with the swivel arm so that I could position it more optimally. For small boards on a benchtop it does the job it said it would do. Man, is it really just a 200mm case fan with a carbon filter? Edit: 120mm apparently and AC. Looks like people replace it with a decent DC fan for higher airflow. Bondematt fucked around with this message at 06:01 on Feb 9, 2022 |
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Feb 9, 2022 05:58
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ante posted:How many cells is the 18V battery? They are 5 cells for 16.5v to 21v. Nominally 18-18.5v. Typically these cells are 18650 in parallel pairs and larger AH batteries just add more to each cell. You'll see them advertised as 20v by certain brands, but they are all the same except for something like Dewalts Powerstack which is just large 5 flat cells for the best use of volume and has a high Amp rating.
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Feb 13, 2022 20:07
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petit choux posted:
This is correct. It's basically a potentiometer without the mechanical stops, so it wraps from max value right back to min. IE if 0* is minimum resistance, 359* is maximum. Going from 359-0 means going from max to min directly. Typically there is a pretty bid deadzone there too, like 340* to 359* is all max value. I can't see a reason for using these over a rotary encoder, but there has to be some reason for their existence. Edit: The one you linked here appears to have a dead zone between 330*-359*. Probably just shows 110KOhms for that range. https://www.digikey.com/en/products/detail/bourns-inc./3382G-1-503G/2080229 Bondematt fucked around with this message at 09:26 on Feb 19, 2022 |
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Feb 19, 2022 09:17
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Combat Pretzel posted:Here's some stupid question in regards to make a battery-based power supply with hot swappable battery blocks. As in hook up the new one, remove the old one. I suppose the safest way would be to have two boost converters, for each input, to bring it to a specific matched voltage, and then feed into one or more buck converts to output desired voltages? The cheap version would be mucking about with diodes into boost-buck converters? You're probably looking for switchover circuit ICs. They typically drive MOSFETs to isolate the batteries and can be setup to select the highest voltage battery. Bonus is some switch fast enough that if you unplug the wrong battery it'll still maintain power. Edit: Looks like they go by Powerpath controller as well Bondematt fucked around with this message at 01:23 on Mar 7, 2022 |
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Mar 7, 2022 01:20
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His Divine Shadow posted:I've used up my inventory of desoldering braid, man I wish I had a proper desoldering station. Why are they so expensive? Like hundreds of euros easily! 1) It's a pump and iron that needs to be isolated from 300*c solder flying in without jamming up. There's a reason the pens are so prevalent still, it's a hard problem to solve in one unit. 2) You don't want to insulate it, the reason it's so long is to dissipate the heat before it gets to the handle. I've seen one with a short tip and active cooling, but can't seem to find it now.
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Mar 12, 2022 19:07
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Hypnolobster posted:Most impressive yard sale score of my life, particularly because I rarely ever stop at yard sales. Getting an unused desoldering gun for 1/15th the price. Just garage sale things
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Jul 7, 2022 22:11
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I highly recommend these little guys for basic buck converting. https://aliexpress.com/item/2251832463081849.html?spm=a2g0n.order_detail.0.0.15f3f19cRtEvYn About a third of the footprint of an lm2596 buck converter and only a few MMs tall. I have one inside my Pi 2 case dropping 24v to 5v and another on the part cooling fan for my 3d printer dropping 24v to 18v to cut down on noise. Cuts down a lot of bulk since you can pretty much stick them anywhere in an existing case. Probably going to use a third for LEDs on the printer soon as well. Not sure how well they handle high loads, but for low power they seem great and don't generate any noticeable heat. The pot on them is good enough to dial in a specific voltage, unlike a cheap buck/boost I have where I barely touch it and it moves entire volts on the output. Bondematt fucked around with this message at 22:10 on Aug 8, 2022 |
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Aug 8, 2022 20:41
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Just think of scratched off traces and jumper wires going in random directions as adding personality to the board.
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Aug 30, 2022 20:01
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Whelp, I just learned a, thankfully cheap, lesson in buying cheap components. Picked up 100 packs of 3mm IR LEDs and Receivers on amazon to make some extra sets of eyes for my old paintball gun. Got one all wired up, plugged it in, and the range of detection is only like 1/4"-1/2" and in a very narrow FOV. Tried running the emitter "hot" at 1.5v using my supply and still barely made it further than 1/2". Got the real deal coming, but going from the LEDs costing 15 cents to $1 a pair, which is basically nothing compared to the time it takes to wire it up.
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Oct 5, 2022 08:37
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Shame Boy posted:Meanwhile, Fusion360 now only lets you make 10 documents total on the free tier apparently, since Autodesk just hates the idea of people actually using and liking their software. 10 editable at once, but I don't think there's a limit on read only and you can go back and forth pretty easily. Still dumb as poo poo, almost as dumb as forcing it to be cloud based so you can't even export without internet.
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Feb 15, 2023 18:16
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Is there any reason I couldn't/shouldn't use a properly rated MOSFET to control power for my 3d printer instead of a relay? 24Vdc power supply wattage would be 300w but I don't think the printer can draw more than 220w. So 10-13 Amps range. I'd be switching after the power supply, so it'll be 24Vdc. Would something like an irf3205 work, and is there a way to calculate the heat dissipation I would need? I'd be driving the MOSFET with 12v, so should be at minimum resistance. It would only be switched on and off when starting/ending a print session. Just trying to shrink my electronics case if I can.
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Mar 2, 2023 20:27
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Shame Boy posted:8m ohms at let's say 15 amps to be conservative would be ~1.8W of heat dissipation, which an IRF3205 could totally handle just fine but you probably want to strap a heatsink to it just so it doesn't get too toasty since it'll be dissipating that constantly for hours at a time. How would you switch the thing though? An N-channel MOSFET would require low-side switching, I assume the relay was switching either the entire power supply or the positive output. Correct, the relay was switching the positive output of the power supply. I'm guessing that switching the low side is a no-go on something like this?
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Mar 2, 2023 20:50
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Shame Boy posted:Not necessarily, it just makes it a little more complicated since you have to make sure power can't return via any other path. The printer may have been designed in a way that assumes that negative you want to switch can just be safely commoned with every other negative of every other component, and now that assumption isn't true anymore. Yes, the entire printer post power supply. So control board with delicate electronics which also has the heating elements run by the controller's mosfets. I would not assume good electrical design here, it's a Creality Ender 3 V2. I'm a Newby when it comes to electronics like this, so yeah definitely seeing why they use a relay on the positive. That's a lot of potential that you are taking the ground away from if you switch the negative.
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Mar 2, 2023 21:08
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Shame Boy posted:Yeah ok switching the entire thing like that probably isn't a great idea. Can you just find a smaller relay maybe? Not sure you'd be able to get a MOSFET + heatsink that was all that much smaller than a small relay anyway. Probably could get a smaller relay. Right now it's a big one built for 240v 30a which is definitely overkill. It's also on a board with a lot of wasted space. Thanks for your help!
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Mar 2, 2023 21:28
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That's super neat, and yeah when the printer initially turns on its only taking a couple of watts for the control board. Hotend & Heatbed take the majority of that 220W, but those are off at boot.
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Mar 3, 2023 00:50
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cruft posted:
I have zero practical use for this but some part of my brains wants one so I can make it go clickity clack.
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Apr 18, 2023 08:17
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kid sinister posted:Eh, just make yourself a Clackotron.
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Apr 18, 2023 18:50
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Cojawfee posted:I specifically went with a pinecil instead of the hakko because I heard too many horror stories of people thinking they are changing the temperature but instead just changing the calibration. Why the hell is that the default thing that happens when you push the button? That has to be a firmware glitch they just decided not to fix. One button sets and the other calibrates, it's real dumb but if you know that you'll be fine. Bad UX is bad.
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Apr 24, 2023 01:28
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Sagebrush posted:if i were in charge, i would have made it so that holding either button down for a second enters temperature setting mode, and holding both simultaneously for a much longer time recalibrates. or if they were willing to add one extra tac switch to the BOM, i'd have a shrouded recalibrate button on the back that you have to push with the tip of a pen. I mean poo poo, they made getting into the settings harder than calibrating, and 100% could have used the same "Hold button while turning it on" here.
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Apr 24, 2023 03:06
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Hey I had to re-calibrate once, and in a hurry! after accidentally changing the calibration instead of the set temp so it was waaaaaaaay hotter than it should have been
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Apr 24, 2023 03:24
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I love the fact it got stencilled and ovened. No checks after stencilling at all it seems. Is there tin in what look like grounded screw holes?
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May 27, 2023 07:02
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I managed to toast a Arduino Nano clone. Guess who's putting 24v, 19.5v, and 12v on all their barrel jacks now? Cheap lesson at least. Kinda crazy that these all use the same exact connector with no real standard to let you know without examing the brick itself.
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Jul 17, 2023 22:38
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Seems like it would be easier just to shock them OP.
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Aug 1, 2023 22:04
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Just spent 2 hours diagnosing a reversed capacitor. Turns out, when you rush to replace an out of stock component, you should really go look at the footprint to make sure the pins are the same. Who knew?! Surprisingly, there is no damage to the battery or the board. Even that capacitor seems fine.
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Nov 29, 2023 23:27
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kid sinister posted:Meanwhile I just have my Hakko. Maybe I'm missing out by going cordless? The ones posted here aren't cordless, just don't have a base station. Controls are on the iron and it plugs into a wall wart or power bank. They're nice, but Hakko just works too. Except for that stupid "hold up to calibrate" thing. What a dumb decision that was.
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Jan 4, 2024 06:00
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Some dash cams use super caps instead of batteries for their acceleration triggered recording. Keeps the RTC and acceleration sensor running, when triggered it records like 30 seconds after the hit. Not super useful, but at least tells you when it happened and you might be able to get the make/model/color.
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Apr 13, 2024 07:54
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