Convert ATX Computer Power Supply for USB 

Yeah, when I made it I thought I'd use the USB option a lot but have ended up using the other outputs more.

I agree, it's always more fun to transform something than to start from scratch. Greetings from Canada.

I took the basics of communication theory! (Maxwell's equation for an electromagnetic wave derived in a dream)

How's that subscription going?

Build useful stuff or repair their broken stuff. That'll show 'em.

ru-vid.com/show-UCMJeKn3Ce20GcPIdUUCbHIAfeatured

Our significant others still wouldn't care 😂

@@ernieschatz3783 100%

It's my pleasure. I'm glad to have given you the inspiration. I know I've appreciated it when others have done the same for me so it's always a pleasure to return the favor. I haven't uploaded videos because I've taken on a full time job which has me travelling a lot. I still hope to find time to make more videos.

Thanks! Greetings from Canada.

Thanks!

Thanks! Glad to hear it!

Yeah, I agree. Someone else recently pointed out something similar except in that case it was because of the thin wires in the cable I reused for connecting to the USB board -- they might not be able to handle high current. I've been using it to power servo motors, normal USB uses hadn't occurred to me.

Ouch. I hadn't heard. Grant was a great guy. His passing is a loss to all he helped and shared with.

RimstarOrg 1 mês atrás I miss making all these videos for you. I recently started a new job, one involving teaching (!), and so I've focused on that until I'm up to expert level there. I'll do more videos then.

Hi. Welcome!

Thanks. Good suggestions. I especially like 2. I'm all for preventative things like that.

@@RimstarOrg Actually suggestion 1 came from an Amphenol service bulletin I read while managing a tech shop in the 1980s.

Yes, you can use one wire of each color. I'm pretty sure each wire's diameter is rated for the rated available current otherwise it wouldn't work in a computer.

Yes! A V12 to power a lawnmower sounds awesome! :) Seriously though, for portability I either had to bring batteries (wouldn't last the two days of the Makerfaire and there's no time to recharge), bring my desktop computer (no way I was doing that, and no laptop), or make this. And this will be useful for many more things too. Regarding the fuses, some places I read said you needed them and others indicated what you're saying. No way I was going to take a chance on that internal fuse blowing at an inconvenient time since it'd be a nightmare to replace. A lot easier to play it safe and have easy to replace fuses. Re the 3V3 feedback wire, I was aware of it but it just didn't come up in my case. Maybe I should have mentioned it anyway.

RimstarOrg If you do not want the internal fuse to blow, then you should have the external fuses 'set' to a lower amperage. (That way they blow before the internal one(s).)

+RimstarOrg what about the voltage drop across the fuse on the output? It does not seem to affect the raspberry presumably because it has some input tolerances, but I don't know for more sensible electronics

I don't know what the voltage drop is across the fuse but I measured the voltage at the 5-volt binding post and it was 5.24 volts just using the meter so the voltage drop can't have been much.

RimstarOrg whatever happened to lasersaber?

Hi kieron, I'm glad to hear you've stuck around all this time. I don't know for certain that this power supply will limit the current to the maximum amount written on the sticker on the power supply. But if the load tries to draw any amount up to what's written then the power supply will give it. So if the sticker says the maximum is 22A and the load tries to draw 5A then the power supply will give it only 5A. And in case you go shopping for them, merret is spelt marrette, which is actually a brand name but that's what many people call them. A more generic name is twist-on wire connector.

@@RimstarOrg Thank mate, thats cool. Good to know devices will only draw as much as they need hmm... Ive just made a "camper" trailer and put 12vs in it too for lighting and power supply (camera). It means i can just rock up, cook my food and then kip in my car. Here in the UK our cars are tiny lol, thought id share :) Just got back from Wales. Needed it, i like the peace and the quiet of nature. ibb.co/DpPMS4m ibb.co/w7kpjhm ibb.co/gVDb1hN ibb.co/NpD5Gfv

Keep in mind that I was talking about the specific power supply in this video. A battery would behave similarly. However, some power supplies allow you to limit the current to something below their maximum, called current limiting. Nice job on the trailer.

@@RimstarOrg Thank you. I appreciate it. Have a good one, all the best kieron

I'll have to check my notes, I know I got that from a webpage but don't have access to the right computer at the moment (it takes a while to boot up and I have to get going). You want to dissipate power and taking it from the largest source make sense to me. But I'll find that reference for you anyhow this evening.

Thank you

Here's the reference. The stuff on dummy loads is near the bottom.

Where's the reference?

Whoops. pcbsmoke.wordpress.com/2012/11/21/converting-an-atx-power-supply-into-a-dc-bench-supply/

Yeah, I agree. It would have looked better.

I bought it from a local electronics store.

It's possible that what goes wrong is that the insulation on a live wire (the 5V wire for example) goes bad and the copper part of the wire touches the metal case of the device which is plugged in but not necessarily turned on. If that case comes in contact with something which is grounded then there will be a high current electrical path from the live wire to the case and then to ground, not even involving the ground wire. So we put the fuse on the live wire. It's done the same way with household wiring in North America, except there the question would be why do we put it on the live wire (HOT) and not on the neutral. See my video about What is Ground for diagrams and explanation ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-zLW_7TPf310.html. It applies to this PC power supply too.

I don't have a record of how much my resistor cost but I did buy an extra one so it couldn't have been too much, certainly less than $10.

@@RimstarOrgforum.cxem.net/uploads/monthly_2017_01/image067.jpg.2a6ac673a795a8dffb6eee742e14a4c6.jpg

You are rigth. Better a powerfull LED lamp.

I use Sony Vegas Movie Studio Platinum 11 (a pretty old version) but I they've since been bought by Magix www.vegascreativesoftware.com/us/

Yeah, for normal usb uses, the current will be too high, as you measured. I use it for powering servo motors, not the usual application. The only thing I can suggest is to put a low current fuse to protect your phone. Your converter idea might be the way to go.

I would be worried about plugging in a phone, unless I were certain that the phone had sufficient current limiting circuitry.

Yeah, the tradeoff is expensive parts bought in the stores locally vs a longer wait time/possibly low quality. Sometimes I don't want to wait.

Thanks! You should be able to charge your cellphone but you should put a 2.5A fuse on the 5V USB wire going to the USB board. This was a good suggestion by Jarrod Coombes here in the comments. I didn't have normal USB applications in mind when I made this -- I use it for powering servo motors. Some normal USB devices assume the current is limited to much lower than it is in this power supply and don't provide their own protection so the fuse should add protection for those devices. You still charge it at your own risk though.

I just remembered that someone else here in the comments suggested using the purple wire for the USB instead. It's 5V and 500mA.

Thanks for your reply @RimstarOrg

This was the only use I had to the board. Gradually I'll have stripped everything useful from that old computer and throw what's left away. This way, the USB boards gets to be used again. It's good to know that you can buy them though. I'm sure I'll need more at some point. Thanks. Regarding the size of the wires in the PSU, they were all 18 AWG. I know that because I used the 18 AWG sized hole on my strippers to strip them.

Cool idea! I don't know if I'll do it but it sure sounds like it would be fun.

@@RimstarOrg YES. Please search for Wire Sound Recorder on the internet and you will get a lot details. This was a very basic device which illustrates the basic details of analogue sound recording techniques

Good catch! You're right. In my diagram, I show the dummy load connected to the 5V but when I actually test it, I connect it to the 12V like I said I would. I chose the highest power source because it should be able to handle the high load better, so go with the 12V. Connecting it to 5V in the diagram was an error. Thanks!

@@RimstarOrg 👍🤞It's fine. I'm happy. I will make sure that I can connect the circuits properly. Because I don't have basic knowledge in electronics And I am training to learn from videos in RU-vid I thank you very much

I don't think they'll be enough. Even my 10w10ohm resistor got hot enough to cause a little browning of the poster board that it was sitting on. The purpose of the dummy load is to be something that you will look like you are powering something. You could also look for a real load, in other words, power something, perhaps an old incandescent lightbulb.

Wow, true enough. I'm actively working on a project but it's still at least a month away from being ready, depending on my work-travel schedule (which can take me away for a week or two at a time). I really want to get a video out before the end of the calendar year.

@@RimstarOrg How about converting an old pc with a 500 power supply into a massive PSU with multiple displays and amperage control knobs? I am designing one in Visio which I started earlier today.

@@RimstarOrg YEESSSS!! HE LIVES!

It might power some things but not others. I don't know how to determine which. I needed them otherwise my motor controller wouldn't work.

@@RimstarOrg Ahh I'm you. Im sure the 5v out from the supply should be ok? I've got loose usb sockets with no circuit.

You can see at 3:29 that the 5V output is rated for 22A, so yes. However, the ribbon cable I reused from the USB circuit board has very thin wires which wouldn't handle even 15A, probably not even 10A. So with suitable wires, and possibly without the circuit board, it should be able to output 20A.

@@RimstarOrg cool thx for the reply im gonna build one. :D

I don't know. As I show in the diagram at around 5:58, the 12V output can handle 10 amps. That's 120 watts (12V x 10 amps = 120 watts). Most soldering tools require less than that. So possibly it would work.

Hi Carleigh. How big is your Van de Graaff generator's dome? That's an indicator of its potential output. The first thing would be to test if your generator is working well. I show a bunch of simple demonstrations you can try here ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Gf6EbRmYImI.html. Very humid air is also bad and will reduce the voltage you can get. Also, make sure there are no sharp metal objects within a few feet of the generator since they may bleed off the charge. The spark length is also a good test (like I do near the beginning of the demo video) but is dangerous to do if you have a big generator and don't have access to a safe Earth ground (I wouldn't want you to damage your production equipment). If the generator seems fine then it may be the bottle. Make sure you use tap water and not distilled water since tap water is more electrically conductive. My bottle was a plastic one with thin walls. I don't know how well a glass bottle will work or one with thick walls. A thick bottom may also make it work less well.

Hi Marinus, I've started a fulltime position teaching at BlackBerry QNX so I don't have as much time as I used to. I'll get back to projects eventually, but not until I'm settled in at this new job.

I don't know if the USB board with the connectors on it which I took from the computer has any current limiting so I can't say for sure. If it doesn't then the 22A would be the limit. However, the ribbon cable which I used has very thin wires in it too and so they'd probably melt at 22A. If all your cellphone uses is 1A or 2A then that should work fine. Note that the amp rating isn't how much the current will be output, it's a limit as to how much is available. It's your load, your cellphone, which determines how much current is output.

@@RimstarOrgtanx

Hmmm... I hadn't considered using it as the low voltage power supply to feed one of my high voltage power supplies (which then feed the tesla coil). It should work. It would be a fixed voltage into the high voltage power supply but at least I have a selection of 3.3V, 5V, of 12V. The current ratings are even higher than the low voltage power supply that I usually use. Interesting.

@@RimstarOrg Thank you, that was very helpful ,Im low on money so ill just go to my local scrapyard and try my best to find parts that i can use and if it won't work i'll just buy old used psu

You're right. Thanks for pointing that out. Hopefully they followed the steps I did as I followed the diagram, then they'll notice that I didn't make that connection. I'll see if I can pin your comment to the top or something.

@@RimstarOrg 👍🤣 It was a long time ago you posted this video so hopefully someone would've been in touch by now if they had a 'head scratching moment' Luckily these supplies are pretty well protected, but I can just picture someone wondering 'why does my power supply keep shutting down🤔?'...lol

Well done you know Ohm's law!

@science mode laboratory - absolutely NOBODY cares whether V=1/Q. You shouldn't concern yourself with it either PS: This is RU-vid, and that's for watching videos.

I've used a power bank normally used for charging phones. A quick search shows that using battery directly is a bad idea though there are some options still. Here's a random webpage that goes through the options along with the dangers www.arrow.com/en/research-and-events/articles/battery-power-your-pi

@@RimstarOrg the RU-vidr great Scott made a video where he build a console and he used batteries ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-_MtN_s4tVK0.html That's the video

Notice he pointed out that the Pi Zero that he used has a DC-DC converter on it, the PAM2306. He also added more battery management circuitry to automatically switch off the power if the battery voltage goes too low.

@@RimstarOrg ok

Sure, I've done it here rimstar.org/equip/negative_voltage_multiplier.htm and here rimstar.org/equip/pos_neg_voltage_multiplier.htm.

@@RimstarOrg Sorry my mistake. I have a bad memory.

Yes. My website is rimstar.org. The Science and Electronics Projects section would be most relevant to this RU-vid channel.

You can try both 5v or 12v. See if one works also there a 3v3 you can look up. It's not in this Video.

Maybe your load isn't high enough.

Thank you but I already fixed it. But my other atx power supply is also not working as well even though I put 10watts 20ohms dummy load to 5v supply.