Thread: found: Mini Power Supply ATX

Good find, I wonder what the input voltage range is? Also, i wonder if it workd with the epia M9000... Is that what your friend is using?

The input range is 12v regulated only. If you hook that directly up to your battery youll be pumping 14.4 volts into your 12v mobo rail, cause there is no on-board 12v regulation on those PSU's.

What youd need to do to use that is get some of those LM7812's to regulate the 12v first.

So am i right in thinking this unit just passes the 12v straight through? If this is the case, then surely it would make more sense to regulate the 12v output of the PS? This way you`ll need a less beefy regulator. Still, i've had bad experience with linear regulators- my hard disk used to spin down due to the voltage drop of the regulator.

Originally posted by MikeHunt79
So am i right in thinking this unit just passes the 12v straight through?

Yes.

then surely it would make more sense to regulate the 12v output of the PS?

Good point! The only reason why that might not work is if the negative 12v is being generated from the +12v rail, rather than one of the lower voltages - in that case I think it would play havoc with your mobo. Id say its more likely to be generating -12v from the +5v line, in which case your idea would work.

As far as linear regs go, you can just keep wiring them in parallel until you get enough current, their cheap enough. I found I only needed 2x LM7812's to run my hard drive and mobo.

Originally posted by phil.45
Good point! The only reason why that might not work is if the negative 12v is being generated from the +12v rail, rather than one of the lower voltages - in that case I think it would play havoc with your mobo. Id say its more likely to be generating -12v from the +5v line, in which case your idea would work.

I Guess someone's gonna have to experiment with this PS to find this out.

I`ve actually found my motherboard works fine without the negative voltages... I just cut the negative voltage wires of my normal AT powersupply, and it still booted, but i might be one of the lucky ones. I was using a very stripped down system.

Originally posted by MikeHunt79
[...]
I`ve actually found my motherboard works fine without the negative voltages... I just cut the negative voltage wires of my normal AT powersupply, and it still booted, but i might be one of the lucky ones. I was using a very stripped down system.

I don't think that the lack of negative supplies will give a problem on any MB while booting. The -12V is know to be used for the RS232 level inverters and some audio periperals, the computer will not be aware of any problems at that level. As for -5V I have no clue what it is used for on an average MB, but I guess it's the same story...

Just incase anyone was wondering, the system was in my car for about 6 months, and it worked perfectly with no negative voltages until the soundcard died. Not sure if the death of the soundcard was related to the lack of negative voltages tho.

Anyway, I take it that this is the same power supply that the cubid case uses? It certainly sounds similar... I would get one myself, but i`m gonna have a go at getting my sproggy working with a epia m9000 when i get one. Wish me luck.

Originally posted by MikeHunt79
Anyway, I take it that this is the same power supply that the cubid case uses? It certainly sounds similar... I would get one myself, but i`m gonna have a go at getting my sproggy working with a epia m9000 when i get one. Wish me luck.

May be the same components but definately not the same size. This one is much skinnier. I just wish they made on a little more powerful though...

Originally posted by MikeHunt79
Just incase anyone was wondering, the system was in my car for about 6 months, and it worked perfectly with no negative voltages until the soundcard died. Not sure if the death of the soundcard was related to the lack of negative voltages tho.

I had the same problem with my soundcard dying. Maybe they are sensitive to the car enviroment.

Also, on my old AT mobo I was using, I didnt have -5v connected and everything was fine, sound card, serial port, parallel port, etc etc all worked.