Learning electronics: Release the Magic Blue Smoke

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KnifeWrench: May 25, 2007; Practical and safe.; Bleak Gremlin

The March Hare posted:

Hi there friends. I've basically never touched anything electronic, but I'm trying to spin a motor using a rpi 3 and an L298N motor controller.

As a first step, I've just tried to get the L298N to turn on. Following directions I found on the internet, I have taken a 12V power supply and cut the end off. I stripped the wires, found the wire with the dashed lines on it which should be + according to reading I've done and hooked that up to the 12v+ thing (what is the name for these? terminals?). I've then hooked the other wire, along with a jumper cable to a ground on my pi, up the the ground... thing. Then I plugged the power supply into the wall, and nothing happened. Near as I can tell, this controller should have a red LED lighting up when it is powered up. What are my troubleshooting steps here?

Troubleshooting step number 1:
Buy a multimeter. If this is a one-off casual project, you can get by with a cheap one, but you get what you pay for, so if you think you'll try more sophisticated stuff, you probably won't regret a nicer one. Bare minimum it needs to do is voltage and resistance.

Troubleshooting step number two:
Check your assumptions. Hook your stripped wires from your 12VDC power supply to your new multimeter, configured to measure DC voltage. This will A) confirm that your power supply isn't a dud, and B) verify your polarity assumption about the wires

# ? Mar 26, 2017 21:45

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# ? May 9, 2024 17:16

Sagebrush: Feb 26, 2012

KnifeWrench posted:

Troubleshooting step number 1:
Buy a multimeter. If this is a one-off casual project, you can get by with a cheap one, but you get what you pay for, so if you think you'll try more sophisticated stuff, you probably won't regret a nicer one. Bare minimum it needs to do is voltage and resistance.

And audible continuity! That feature alone is worth whatever additional cost it is to go from a cheapy Harbor Freight meter up to one that has it.

This mini Extech model is the one I recommend to students who want a decent quality first multimeter. Not auto-ranging and I wouldn't use it for anything over wall-socket voltage, but it's inexpensive and does the job.

https://www.amazon.com/Extech-645618-Digital-Mini-MultiMeter/dp/B0012VWR20/

# ? Mar 26, 2017 21:57

The March Hare: Oct 15, 2006; _{Je r�ve d'un}
Wayne's World 3; Buglord

https://www.amazon.com/gp/product/B01ISAMUA6/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

So I knew that multimeters were useful and I purchased this one in advance. Not sure how to read the thing yet, but I've got the instructions on my desk. Will report back once I light myself on fire or whatever.

Trip report: Figured out how to use it. Measured it in 20 V -/... mode. Was negative when the negative stick thing was on the wire that I thought was positive because it had the dashes on it.

Switched them, and now:

Additionally: Copper desk seemed like a super cool idea when I wasn't mucking about with electronics.

Thanks for the help y'all, I'm sure I'll be back for more advice~

The March Hare fucked around with this message at 22:38 on Mar 26, 2017

# ? Mar 26, 2017 22:09

Sagebrush: Feb 26, 2012

Yeah the whole "white stripe on the wire indicates positive/negative" thing is probably the worst-implemented "standard" there is, as suggested by how I can't even tell you which way it's supposed to be. Test every power supply before you plug it into your device, IMO.

# ? Mar 26, 2017 23:44

taqueso: Mar 8, 2004

Definitely a good idea to make your devices resilient to reverse polarity, its a really common error even for veterans.

# ? Mar 27, 2017 00:02

huhu: Feb 24, 2006

I'm looking to read in a signal from a music system via an aux cord and then control two DC motors independently depending on wether the left or right speaker is making nose. I thought I'd be able to do this easily with the Arduino but it doesn't look like it. Anyone have any suggestions for where to start?

Edit: I found this -

http://interface.khm.de/index.php/lab/interfaces-advanced/arduino-realtime-audio-processing/

So I shall start there.

huhu fucked around with this message at 02:01 on Mar 27, 2017

# ? Mar 27, 2017 00:58

The March Hare: Oct 15, 2006; _{Je r�ve d'un}
Wayne's World 3; Buglord

Good to know. My new problem is that I cannot for the life of me figure out how to make this thing rotate rather than just jump all the heck over the place. I've got the stepper plugged in as follows:

Coil : RPi 3 GPIO Board #
A+ : 16
A- : 18
B+ : 38
B- : 40

I'm sending the following sequence with a 1ms delay between them based on something I found on the internet about how to drive a bipolar stepper motor:

a/a-/b/b-
1000
0010
0100
0001

It moves, sometimes mostly in the correct direction, but always ends up flipping around and flapping about.

Is it a timing thing or do I need to find the manufacturer specs for the motor I bought or what?

(in case it is in any way helpful: http://www.omc-stepperonline.com/bipolar-stepper-nema-17-54v-085a-36ncm51ozin-17hs150854s-p-103.html is the motor I have)

Further edit: I guess maybe it is controller specific, and not motor specific? I found this which seems to have a table for the phases: https://picclick.com/DC-Stepper-Motor-Dual-H-Bridge-Drive-Controller-321897484401.html so I also tried those: motor just vibrates a bunch.

The March Hare fucked around with this message at 01:36 on Mar 27, 2017

# ? Mar 27, 2017 01:05

Sagebrush: Feb 26, 2012

The sequence is correct, but 1ms might not be a long enough time for the motor to keep up. Try 10ms instead to start. Can your power supply source enough current for the motor? If it's too little, you'll definitely just get vibrations instead of movement.

Also, a Raspberry Pi isn't ideal for this. It doesn't have a real-time operating system (usually) so you can't guarantee the timing accuracy of GPIO outputs beyond a certain level. A hard-real-time microcontroller like the Arduino is a better strategy.

# ? Mar 27, 2017 01:52

ante: Apr 9, 2005; SUNSHINE AND RAINBOWS

Depending on your application, exact timing may not matter so much. Testing at 10 or even 100ms is a good idea though

Your sequence is wrong, try this:

a/b/a-/b-
1001
1100
0110
0011

Note the winding order, this way is less confusing (to me)

# ? Mar 27, 2017 02:10

PBCrunch: Jun 17, 2002; Lawrence Phillips Always #1 to Me

I've been doing some little projects with ESP8266 that involve connecting other "stuff" to the ESP module. I'd like some keyed connectors of various sizes that would allow me to connect and disconnect as needed.

I like Dupont wires and how easy they are to work with. Ideally, I'd like some kind of keyed Dupont wire headers. I don't really want to buy a crimp tool for 22 AWG wires, but I will if I have to.

What is the go to setup for putting keyed connectors onto perfboard/stripboard?

# ? Mar 27, 2017 05:08

sharkytm: Oct 9, 2003; Ba

By

Sharkytm doot doo do doot do doo; Fallen Rib

Molex KK 0.1"? Cheap, cheap crimpers, and can be ramped/keyed.

# ? Mar 27, 2017 05:25

Zero VGS: Aug 16, 2002; ASK ME ABOUT HOW HUMAN LIVES THAT MADE VIDEO GAME CONTROLLERS ARE WORTH MORE; Lipstick Apathy

I was checking out some Tesla battery cables I have, and noticed they seem to be using some kind of cold-weld by just jamming the wiring straight on to the flat copper tabs:

Is there an affordable hydraulic crimping tool and tabs to do this myself, or does it require some kind of industrial press? It's really cool and the tabs have much more surface area hitting the battery terminals than a normal 2/0 lug would.

# ? Mar 27, 2017 19:51

Zero VGS: Aug 16, 2002; ASK ME ABOUT HOW HUMAN LIVES THAT MADE VIDEO GAME CONTROLLERS ARE WORTH MORE; Lipstick Apathy

I got an easier one for y'all too... anyone know the name of this socket connector?

Edit: It has 15 pins.

Zero VGS fucked around with this message at 00:58 on Mar 28, 2017

# ? Mar 28, 2017 00:54

KnifeWrench: May 25, 2007; Practical and safe.; Bleak Gremlin

Zero VGS posted:

I got an easier one for y'all too... anyone know the name of this socket connector?

Edit: It has 15 pins.

Looked like a JST PA series to me, and this guy agrees:
https://teslamotorsclub.com/tmc/threads/in-development-inexpensive-custom-bms-for-tesla-battery-modules.51095/

# ? Mar 28, 2017 01:15

peepsalot: Apr 24, 2007; ��PEEP THIS...
��BITCH!

Zero VGS posted:

I got an easier one for y'all too... anyone know the name of this socket connector?

Edit: It has 15 pins.

What is the pin pitch? Measure between centers of the outermost pins and divide by 14.
Are there any markings (indicating mgfr, etc) on the connector?

# ? Mar 28, 2017 01:18

Zero VGS: Aug 16, 2002; ASK ME ABOUT HOW HUMAN LIVES THAT MADE VIDEO GAME CONTROLLERS ARE WORTH MORE; Lipstick Apathy

KnifeWrench posted:

Looked like a JST PA series to me, and this guy agrees:
https://teslamotorsclub.com/tmc/threads/in-development-inexpensive-custom-bms-for-tesla-battery-modules.51095/

Ah, thanks, good find! Looks like I need the S15B-PASK-2 as the female end.

Yeah, that guy is the foremost Tesla battery hacker so I've been following his notes very carefully, but he has a lot of information buried through lots of posts.

Edit: I was going to use some JST li-po balance cabling but now I'm thinking I should just get the female ends, solder them to female RJ-45 jacks, and make the runs with Cat5. These are all going to a battery management system that balances the individual cells at a max rate of 200 milliamps per cell so that's fine for 24 AWG Ethernet, and no data going over it so crosstalk shouldn't factor much.

Edit 2: Jeez, people don't gently caress around with the minimum orders on these... I only need 14 but the best I can find is a place with no minimum quantity, but a minimum order of $75

Zero VGS fucked around with this message at 01:39 on Mar 28, 2017

# ? Mar 28, 2017 01:25

Sagebrush: Feb 26, 2012

Can't find them on Digi-Key or Mouser?

# ? Mar 28, 2017 06:24

BattleMaster: Aug 14, 2000

So I just had an adventure in repair that almost ended poorly (for the device under repair, not for me, at least.)

I bought an Eberline ASP-1 Geiger-Mueller counter a while ago that was used surplus from the US government. It was dirty from having been dragged around in the field for years but it functioned beautifully, except for the fact that the analog meter on it got stuck at the high and low ends. I did some research into problems with analog meters and the cause of this was said to be little metal fragments stuck to the magnet in the meter. Apparently these things are so sensitive that even little disturbances like that can screw them up.

I took the device apart and removed the meter and opened it up, and lo and behold there were itty bitty little dust mote sized metal fragments stuck to it. I removed them with a bent paperclip and it regained the range of motion. Except that I hosed up putting it back together and snapped the meter's needle.

I panicked and considered replacing the meter altogether with another 0-100 uA model I had, but it came nowhere close to fitting. So out of desperation I superglued the needle back together which took several tries. I put the unit back together and now it functions beautifully except that the needle is a little messed up in a place where I crunched it with my tweezers and the paint came off. The actual point where it was broken isn't visible though, it broke off really close to the pivot point.

What's cool about this particular G-M counter is that it's actually mostly digital with a microcontroller doing all of the rate calculations. The meter is controlled by a DAC except when it's in battery check or HV check modes where it connects directly to those circuits which conveniently avoids needing an ADC or having the micro have to care about those things. The HV is adjusted with a pot but things like tube dead time and efficiency are set with DIP switches and the micro corrects for those when calculating what count rate to send to the meter. I haven't touched those on mine though because I'm assuming that it was properly configured for the pancake probe that came with it.

Anyway I'm glad that I actually managed to get it fully functional. I wanted to take it to work and take some measurements when I use the x-ray imager for an undergrad lab I'm TAing for. I'm kind of curious about how many counts I can pick up at different distances and angles when the x-ray bursts happen.

# ? Mar 28, 2017 08:18

Splode: Jun 18, 2013; put some clothes on you little freak

I tried using a 10W resistor as a heating element today. Turns out, the weird ceramic material they use is not very good at transferring heat. Quelle surprise. Time to get some nichrome wire.

Does anybody have any good methods for making elements/tightish coil windings by hand? I'd rather increase the element resistance than lower the voltage if I can get away with it.

# ? Mar 28, 2017 12:57

Shame Boy: Mar 2, 2010

BattleMaster posted:

So I just had an adventure in repair that almost ended poorly (for the device under repair, not for me, at least.)

I bought an Eberline ASP-1 Geiger-Mueller counter a while ago that was used surplus from the US government. It was dirty from having been dragged around in the field for years but it functioned beautifully, except for the fact that the analog meter on it got stuck at the high and low ends. I did some research into problems with analog meters and the cause of this was said to be little metal fragments stuck to the magnet in the meter. Apparently these things are so sensitive that even little disturbances like that can screw them up.

I took the device apart and removed the meter and opened it up, and lo and behold there were itty bitty little dust mote sized metal fragments stuck to it. I removed them with a bent paperclip and it regained the range of motion. Except that I hosed up putting it back together and snapped the meter's needle.

I panicked and considered replacing the meter altogether with another 0-100 uA model I had, but it came nowhere close to fitting. So out of desperation I superglued the needle back together which took several tries. I put the unit back together and now it functions beautifully except that the needle is a little messed up in a place where I crunched it with my tweezers and the paint came off. The actual point where it was broken isn't visible though, it broke off really close to the pivot point.

What's cool about this particular G-M counter is that it's actually mostly digital with a microcontroller doing all of the rate calculations. The meter is controlled by a DAC except when it's in battery check or HV check modes where it connects directly to those circuits which conveniently avoids needing an ADC or having the micro have to care about those things. The HV is adjusted with a pot but things like tube dead time and efficiency are set with DIP switches and the micro corrects for those when calculating what count rate to send to the meter. I haven't touched those on mine though because I'm assuming that it was properly configured for the pancake probe that came with it.

Anyway I'm glad that I actually managed to get it fully functional. I wanted to take it to work and take some measurements when I use the x-ray imager for an undergrad lab I'm TAing for. I'm kind of curious about how many counts I can pick up at different distances and angles when the x-ray bursts happen.

Doesn't the needle have to be exactly balanced for the readings to be accurate? Then again if it's just a for funsies meter it doesn't need to be that accurate I guess...

e: Oh if the battery test just connects directly to the meter you can probably really easily just run a power supply through it to confirm it's fine

# ? Mar 28, 2017 14:15

Jamsta: Dec 16, 2006; Oh you want some too? Fuck you!

Can anyone recommend a ~6" LCD screen (B&W, not backlit) for use with a micro? Preferably a dotmatrix, but if its segmented that may also work.

Want to make a clock/IoT message alert thing that reads well under sunlight and doesn't emit light itself.

Jamsta fucked around with this message at 15:12 on Mar 28, 2017

# ? Mar 28, 2017 15:10

Shame Boy: Mar 2, 2010

Jamsta posted:

Can anyone recommend a ~6" LCD screen (B&W, not backlit) for use with a micro? Preferably a dotmatrix, but if its segmented that may also work.

Want to make a clock/IoT message alert thing that reads well under sunlight and doesn't emit light itself.

That sounds like the perfect use case for e-ink but I'm not really that up to speed on how that all works

# ? Mar 28, 2017 15:12

Jamsta: Dec 16, 2006; Oh you want some too? Fuck you!

ate all the Oreos posted:

That sounds like the perfect use case for e-ink but I'm not really that up to speed on how that all works

Good idea, when I last looked they were still too expensive, but this looks about right:

https://www.aliexpress.com/item/Original-6-0-e-ink-e-paper-epaper-LCD-display-Screen-For-amazon-kindle-keyboard-D00901/32589664186.html

Not sure there is any micro support for it, looks like a direct Kindle swap out.

e: Looks like a hassle compared to regular Arduino compatible screens: https://learn.adafruit.com/repaper-eink-development-board-arm-linux-raspberry-pi-beagle-bone-black/wiring-the-raspberry-pi-1

# ? Mar 28, 2017 15:41

Acid Reflux: Oct 18, 2004

I've read about a bunch of projects all over Hackaday where people have used an entire Kindle to display all sorts of non-book information. You can pick up a used one on eBay for about that same price as just that replacement screen, and then you'd have a whole little Linux computer with wifi to do your bidding.

# ? Mar 28, 2017 16:00

Jamsta: Dec 16, 2006; Oh you want some too? Fuck you!

Acid Reflux posted:

I've read about a bunch of projects all over Hackaday where people have used an entire Kindle to display all sorts of non-book information. You can pick up a used one on eBay for about that same price as just that replacement screen, and then you'd have a whole little Linux computer with wifi to do your bidding.

That's pretty drat cool! Thanks for the headsup.

Bit overkill for me - was hoping to just use an ESP8266 + Arduino toolchain to do it all.

# ? Mar 28, 2017 16:08

Acid Reflux: Oct 18, 2004

If you're gonna do it, why not overdo it? :v:

# ? Mar 28, 2017 16:14

taqueso: Mar 8, 2004

This page has info on driving the display from a Kindle 2. You could make those waveforms with a microcontroller.

# ? Mar 28, 2017 16:20

Stabby McDamage: Dec 11, 2005; Doctor Rope

Sagebrush posted:

The driver board needs a 5v supply to power its own logic. The 12v line you've connected just powers the motors. I see on the datasheet that the board also has its own 12v-to-5v regulator that can be activated by removing the jumper (a small plastic block stuck on two pins) above the 12v power lines. Have you tried that?

If that doesn't work, it looks like you'll have to provide a regulated 5v supply onto the third pin, marked in your datasheet as connected to 5v VCC from the microcontroller. Connect a wire from a 5v line on the raspberry pi (if it has one, I can't remember) to the third pad next to the 12v lines, as indicated.

In order to spin the motors you'll also need to send a signal from the Pi's GPIOs, but one step at a time.

I had a module of roughly that shape based on an L298N, and it had an onboard 5V reg that was switched with an actual button. So I'd advise to check for a button or jumper that might engage onboard 5V regulation, just to save complexity.

Zero VGS posted:

I was checking out some Tesla battery cables I have, and noticed they seem to be using some kind of cold-weld by just jamming the wiring straight on to the flat copper tabs:

Is there an affordable hydraulic crimping tool and tabs to do this myself, or does it require some kind of industrial press? It's really cool and the tabs have much more surface area hitting the battery terminals than a normal 2/0 lug would.

I don't know about that flat cold weld, but why not just use round crimp lugs appropriate for your wire? Seems like the same (or better) surface area than these flat ones. Here are some for 6 AWG and the accompanying tool. I'd certainly agree that either form of crimp is better than screw-down lugs, though.

# ? Mar 28, 2017 17:51

DethMarine21: Dec 4, 2008

Jamsta posted:

Bit overkill for me - was hoping to just use an ESP8266 + Arduino toolchain to do it all.

These Sharp Memory Displays look pretty cool but are still a bit expensive. It's neat that the activated pixels turn reflective.

# ? Mar 28, 2017 18:02

BattleMaster: Aug 14, 2000

ate all the Oreos posted:

Doesn't the needle have to be exactly balanced for the readings to be accurate? Then again if it's just a for funsies meter it doesn't need to be that accurate I guess...

e: Oh if the battery test just connects directly to the meter you can probably really easily just run a power supply through it to confirm it's fine

When I set it to integrate mode and kept a mental count of the clicks I could hear from background radiation, my count agreed with the count displayed on its meter.

I wouldn't use it for actual science (my job pays for equipment for that anyway) or in a life or death situation, but even with my bodged needle repair I think that it's probably better than most things you could get your hands on as a hobbyist.

If the meter breaks again I'm going to devise a digital display for it or something, because the signal to the meter is just a 0 to 100 uA current so it should be easy enough to work with.

# ? Mar 28, 2017 20:28

MRC48B: Apr 2, 2012

Splode posted:

I tried using a 10W resistor as a heating element today. Turns out, the weird ceramic material they use is not very good at transferring heat. Quelle surprise. Time to get some nichrome wire.

Does anybody have any good methods for making elements/tightish coil windings by hand? I'd rather increase the element resistance than lower the voltage if I can get away with it.

Why? Find a junked oven, toaster, electric furnace, hairdryer or other electric heating appliance. Salvage the heating coils.

If you need new coils, look for a "Heating element Re-string kit".

Unless you just wanna mess with coil winding, in which case the answer is a cylindrical form that spins in a supporting frame.

# ? Mar 28, 2017 22:56

Zero VGS: Aug 16, 2002; ASK ME ABOUT HOW HUMAN LIVES THAT MADE VIDEO GAME CONTROLLERS ARE WORTH MORE; Lipstick Apathy

Stabby McDamage posted:

I don't know about that flat cold weld, but why not just use round crimp lugs appropriate for your wire? Seems like the same (or better) surface area than these flat ones.

I have a handheld hydraulic crimper for round lugs, but it doesn't look like much surface area on those lugs would actually hit the terminals on the battery. I'm using 2/0 cable, but the area of the mating surface seems like it might be a little less than the diameter of the cable, which I assume could create a possible hotspot? Or does it not work that way?

The terminal has a bolt that screws into it to clamp those flat lugs like I showed, but the hole is so wide that only the outer extremes of a 2/0 log would touch. Maybe I could ease the transition by getting some wide flat copper bus bar, cutting them into squares, and drilling a hole in the middle of each to make a copper square washer as a intermediate between the lug and the terminal. I'll take a picture when I can make it back to the batteries.

Sagebrush posted:

Can't find them on Digi-Key or Mouser?

Not on Mouser, and Digikey wants minimum order of 200, gently caress it, I'll just cut off the connectors and solder some PCB-mount ethernet jacks directly to the wires instead.

# ? Mar 29, 2017 02:16

KnifeWrench: May 25, 2007; Practical and safe.; Bleak Gremlin

Zero VGS posted:

Not on Mouser, and Digikey wants minimum order of 200, gently caress it, I'll just cut off the connectors and solder some PCB-mount ethernet jacks directly to the wires instead.

Please don't make me imagine a kludge of this magnitude driving down the road. Soldering wires to board mount connectors in order to make a cable should only be done on a bench, when there's no other option.

Fortunately for you, free-hanging RJ-45 connectors do exist.

https://www.digikey.com/short/3wqd5q

# ? Mar 29, 2017 03:17

The March Hare: Oct 15, 2006; _{Je r�ve d'un}
Wayne's World 3; Buglord

Update time!

Thanks for the tips y'all, I tried a bunch of the stuff everyone posted out but nothing really worked. Through raw guess and check, I have arrived at the following state:

http://tinypic.com/player.php?v=9t2xav%3E&s=9

using the following code:

code:

import RPi.GPIO as gpio
import time

try:
    steps = 20000

    gpio.setmode(gpio.BOARD)
    
    pins = [16, 18, 38, 40]

    for pin in pins:
        gpio.setup(pin, gpio.OUT)
        gpio.output(pin, 0)

    seq = [
        [1, 0, 0, 0],
        [0, 0, 1, 0],
        [0, 1, 0, 0],
        [0, 0, 0, 1]
    ]

    for step in xrange(steps):
	print 'REDDIT.COM/R/FIDGETSPINNERS'
        for s in xrange(len(seq)):
            for p in xrange(len(pins)):
                gpio.output(pins[p], seq[s][p])

            time.sleep(0.001)
finally:
    gpio.cleanup()

This is the best rotation I've gotten out of the thing yet. But, as you can see in the video, it is infrequently but occasionally changing direction without my asking it to do so. Googling indicates a whole host of things can cause this, so I guess I'll just keep loving with it until I get tired of it and buy an Arduino or something.

# ? Mar 29, 2017 03:30

Zero VGS: Aug 16, 2002; ASK ME ABOUT HOW HUMAN LIVES THAT MADE VIDEO GAME CONTROLLERS ARE WORTH MORE; Lipstick Apathy

KnifeWrench posted:

Please don't make me imagine a kludge of this magnitude driving down the road. Soldering wires to board mount connectors in order to make a cable should only be done on a bench, when there's no other option.

Fortunately for you, free-hanging RJ-45 connectors do exist.

https://www.digikey.com/short/3wqd5q

It's not really to make a cable; I was gonna cut off that JST 15-pin plug you saw in the picture, solder the free battery wires to the RJ-45 pins, trim the pins, flatten the wires against the RJ-45, pot it all in epoxy, and fasten it to the battery pack. That way it's just a female RJ-45 interface that can't budge, and I hook it to the BMS with an ordinary ethernet cable.

# ? Mar 29, 2017 03:43

Splode: Jun 18, 2013; put some clothes on you little freak

MRC48B posted:

Why? Find a junked oven, toaster, electric furnace, hairdryer or other electric heating appliance. Salvage the heating coils.

If you need new coils, look for a "Heating element Re-string kit".

Unless you just wanna mess with coil winding, in which case the answer is a cylindrical form that spins in a supporting frame.

it's a uni project, so I was hoping to make something custom to show off, but you are right. In the end I just bought a $12 hairdryer, and put a relay on the active.

# ? Mar 29, 2017 08:38

poeticoddity: Jan 14, 2007; "How nice - to feel nothing and still get full credit for being alive." - Kurt Vonnegut Jr. - Slaughterhouse Five

Today I learned that OSHPark supports directly uploading *.kicad_pcb files, which means you don't have to make and manually rename gerber and drill files. :toot:

I don't know if that's new or I just somehow missed it previously, but I figured that info might come in handy for someone else, too.

# ? Mar 30, 2017 04:02

Stabby McDamage: Dec 11, 2005; Doctor Rope

Zero VGS posted:

I have a handheld hydraulic crimper for round lugs, but it doesn't look like much surface area on those lugs would actually hit the terminals on the battery. I'm using 2/0 cable, but the area of the mating surface seems like it might be a little less than the diameter of the cable, which I assume could create a possible hotspot? Or does it not work that way?

The terminal has a bolt that screws into it to clamp those flat lugs like I showed, but the hole is so wide that only the outer extremes of a 2/0 log would touch. Maybe I could ease the transition by getting some wide flat copper bus bar, cutting them into squares, and drilling a hole in the middle of each to make a copper square washer as a intermediate between the lug and the terminal. I'll take a picture when I can make it back to the batteries.

If you're that concerned, I'd just find a reputable site for the 2/0 lugs and see what they're rated for.

# ? Mar 31, 2017 04:17

Methylethylaldehyde: Oct 23, 2004; BAKA BAKA

Ok goons, I have a need for a ~36 volt power supply for a project, and I have two ways of doing it. One would be to get three 12V lead acid batteries in series and schlepping around 50 pounds of battery, the other choice is to do something like this to a Dewalt 40v battery pack. I'm leaning more toward the battery pack mod, just because eventually this project is going to need to be something you can easily carry.

On a scale of 'UL certified' to 'aboveground pool in the basement' how stupid is this mod?

# ? Apr 1, 2017 20:27

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# ? May 9, 2024 17:16

CarForumPoster: Jun 26, 2013; â¡POWERâ¡

Methylethylaldehyde posted:

Ok goons, I have a need for a ~36 volt power supply for a project, and I have two ways of doing it. One would be to get three 12V lead acid batteries in series and schlepping around 50 pounds of battery, the other choice is to do something like this to a Dewalt 40v battery pack. I'm leaning more toward the battery pack mod, just because eventually this project is going to need to be something you can easily carry.

On a scale of 'UL certified' to 'aboveground pool in the basement' how stupid is this mod?

There are also probably adjustable DC-DC converters you could just use the regular battery with so youre not fuckin around with anything.

Something like this: https://www.amazon.com/GEREE-Conver...in%3A2888021011

Except rated for whatever you need.

# ? Apr 1, 2017 20:32

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