ATX Breakout board - yet another group project?

Each voltage has a 2A polyfuse in the circuit. The board also drives the power on/off pin.

That begs the question: Why is a polyfuse necessary? What if he wants more current?

I don’t know the answer specifically, @Scriven, but I do know that ATX power supplies often don’t behave when there is a an very uneven load on the different voltage rails. This project is cool and useful for hobbyists, but is definitely abusing the power supplies a little bit.

The 20+A that most modern power supplies can produce (continuous!) is pretty dangerous to the breakout board itself, any wires/connectors in the circuit etc. This design is clearly not designed to support high current, and includes enough protection that you’re unlikely to burn your house down using it.

If you need more current, you need something more robust.

I think most modern PSUs should have reasonably good load regulation on all rails even with imbalance; I believe this is required by the latest ATX specifications, but certainly if you’re expecting to use it in an unbalanced situation, you should test this.

Hence the hunking big traces prior to the fuse.

I’ve always wondered that about pc power supplies, they’ll deliver all this current down any one of the n wires on a particular voltage. I don’t see any one wire capable of carrying 40A on the output, this doesn’t even feel legal to me. I guess given the connector on the end is fixed you can mandate that the wires be used in parallel (but what about the HDD connectors, I reckon you could pull enough current down one of those to melt them).

Basically, I’m looking for a single bench source for lots of little(ish) 12V/5V things (external drives, RPI/other SBC, USB Hubs), as I"m sick of lots of 12V/5V adapters cluttering up my power bars.

My original thought was to just buy an extension, wire up the appropriate wires to a switch and put Anderson PP ends on the 12/5V sources I want to use for my various projects.

I was very curious to see this, but wasn’t sure why there was a 2A limit for each voltage, when my simple understanding of the power supply output information looks like there’s far more total amperage available than that, granted spread out over many wires. Each project I don’t expect to pull lots of power individually, so was hoping to power many from one source.

You could use a different fuse with careful design.

I’ve also made some little molex breakouts that take the 5V and 12V from the HDD connector and do the same thing (leds and polyfuse). I am still waiting on the pcb mount molex connectors to test them out. I have 10 so I can sell you some kits soon.

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Ah, I’ve also done a wire version of this! I got a molex extension and cut the wires, wiring up 12V to powerpoles and 5V to a standard remote control “thing” servo connector. The only issue I had with doing this with a bench supply was turning on the power supply (hated using the jumper wire, always seemed just a little too ‘ghetto’).

So it’s basically what I’ve been doing, but with the added security of fuses and added prettiness of a board and not just wires.

(As an aside, I have found some power supply’s “5V” actually falls outside the given safe 5V range for a raspberry pi, had to try a few old PS’s I had laying around before I found one that tested ‘safe’).

@packetbob
@ashley
@funvill
@garble7
@hjsvhsweb
@wander
@Arrgh
@rsim
@AndrewTilston

I have 9 kits in my locker, one has all black posts, I’ll save it for last and replace the posts when they arrive.

I’ll be at vhs tonight from 8-9:30, sorry about the short notice. Can we round up to $7.00? I ended up paying some shipping on the missing parts.

I won’t make it down tonight or this week, but happy to send you the money
Tom, paypal, interac email money transfer, direct deposit into your bank
account, etc.

I’ll pop down tonight, thanks!

Sweeeet! I’ll try to drop in tonight and will bring cash moneys. Just for the less initiated among us (me), am I to look for a locker that says TomKeddie or something like that and just grab a baggy of ATX bits out of it? And Tom, if you’re not there is it okay for me to leave a small envelope of money in your locker? I’m not sure what the usual process is. Thanks! :slight_smile:

(And thanks again @ashley!)

Andrew, My locker is locked. I can leave a kit for you in the dropbox locker (labelled as such), you can give me the money via paypal or interac if you want.

Sounds good to me! I’ll paypal you, just let me know your address and I’ll do it before I leave today. :smile:

Thank you!!! And after what time should I aim myself at the dropbox locker, just so I don’t go early and you haven’t been yet.

Andrew, I’ll be there until 9:30. Lets leave it to chance, if I don’t see you tonight, I’ll leave you a kit and then you can pay me. It’s not a lot of money.

Are you there now? If so I’ll swing by after work.

As above, not until 8pm, sorry.

Tom, what email address do you want the payment sent to?

tom at bronwenandtom dot com

Thanks,
Tom

For all ATX Break Out Board peoples:
We will be setting up a build night in a couple of weeks for anyone that is interested. The ATX board is pretty simple but it does have some SMD parts. The plan would be to have a reflow oven and solder paste dispenser (use of thanks to @TomKeddie ) that all can use. Once the SMD parts are done you just have to hand solder the switch and power supply connector…

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You can get the orientation of the leds from google images. They will have a T or a triangle under them.

image

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