13 replies to this topic

[Tickled_Pink]

Is there anything I should know about a PC power supply that could stop me from modifying one to power my 8-bit hardware?

Just think it would help my under desk nightmare and PSU shortage issues ... And be a simple project to do - if there are no hidden nasties.

[Rybags]

One consideration is that some need a decent load to work well. The Atari will barely pull 3-6 Watts in normal use which isn't much of a load.

An alternative that I'm looking at is using those cheapish USB wall warts. I've got one that's rated at 1 Amp which should be enough for a machine that doesn't have too much extra stuff leaching power off it, but no idea if you need to make 1 or 2 USB plugs up for it.

IIRC, a normal USB powered device can draw .5 Amp without problems, so yet another alternative could be to power the Atari through 2 USB ports.

[keilbaca]

Rybags, on Sat Jan 21, 2012 1:23 AM, said:

One consideration is that some need a decent load to work well. The Atari will barely pull 3-6 Watts in normal use which isn't much of a load.

An alternative that I'm looking at is using those cheapish USB wall warts. I've got one that's rated at 1 Amp which should be enough for a machine that doesn't have too much extra stuff leaching power off it, but no idea if you need to make 1 or 2 USB plugs up for it.

IIRC, a normal USB powered device can draw .5 Amp without problems, so yet another alternative could be to power the Atari through 2 USB ports.

The wall warts used on external hard drives are 2 Amp. That would work if 1 Amp would work great as it is.

[sloopy]

Better off cutting the connector on a 2A wall wart for a USB hub and using that...

I use an older ATX PSU on my desk, it powers my A8 (can power many of them, but only have conns for 2 connected), and also have a 17" LCD it powers also. I use an older IDE HD for the 'load', even tho i have a ceramic power resistor to put in it, I just havnt intstalled it, and have no problems...


sloopy.

[Tickled_Pink]

I am considering using a mini-itx psu or going the whole hog and getting a modular psu, then just building the necessary cables. Or maybe even building a modular psu out of a mini-itx psu.

[Rybags]

I forgot about the caddy warts. That's another easy option. Although that said, I forgot I had an external drive plugged in for about a day and the wart crapped itself and took out the drive as well.

[HiassofT]

Besides the minimum load issue (carefully check the datasheet, several lines like 5V or 12V might need a minimum load), there's another thing to keep in mind:

Those PC power supplies are usually able to provide 10-25A on the +5V and +12V rails. If you accidentally create a short circuit between +5V and GND on your Atari, there's a high risk of severe damage. Thin traces on the PCB or misplaced components might just vaporize...

I'd recommend using a wall-wart type PS rated at 2A-3A. This is more than enough power for the Atari, even if you have a lot of upgrades installed. I'm using 5V/2A wall-warts with most of my Ataris and retired my old AT power-supply (which also had a silent, but still audible, fan) some time ago.

If you also need the +12V (for a harddrive or a modded 1050), you can of course use a PC power supply - just don't forget to install fast blowing fuses in the power connections to your Atari and peripheral devices.

so long,

Hias

[griz]

How about a Pico-PSU? Then again, at that price you may as well just get a real Atari power supply.

BTW ... what is the problem with using an Atari supply?

[Rybags]

Many of us have more machines that power supplies - I've got 10 but only 1 or 2 good XL PSUs and 2 that can power 400/800/1200XL.

Plus there's a lot of dud resin ingot PSUs around, they go overvolt and kill off machines.

[rdemming]

griz, on Sun Jan 22, 2012 8:35 AM, said:

How about a Pico-PSU? Then again, at that price you may as well just get a real Atari power supply.

According to your link, the Pico-PSU needs a 12V input and not 110/220V. It provides a regulated 5/12V from any standard 12V DC source so you need an additional power adapter. And since it is ATX power supply, it needs some signals to turn it on/off. Just plugging in power does not make it switch on. So it is not really usable to replace a standard Atari power supply.

Robert

[sloopy]

Its an easy source of 3.3V, 5V and 12V for anything i need them for, and its more convenient then having a bunch of different bricks on my desk...

not to mention, unlike some Atari PSU's, when a switching PSU goes bad, it usually puts out no power, not possible overvoltage...

an inline fuse is ALWAYS a good idea, so make sure you have one on your PC PSU...

sloopy.

[poobah]

I love the pico-psu's. I have one in my falcon.

[griz]

Quote

Plus there's a lot of dud resin ingot PSUs around, they go overvolt and kill off machines.

That's true.

Quote

According to your link, the Pico-PSU needs a 12V input and not 110/220V. It provides a regulated 5/12V from any standard 12V DC source so you need an additional power adapter. And since it is ATX power supply, it needs some signals to turn it on/off. Just plugging in power does not make it switch on. So it is not really usable to replace a standard Atari power supply.

Good point about the ATX power switch issue.

I have one of these running from a notebook power supply on a mini-itx atom based server.

Perhaps someone could hack a pico psu into an actual atari power supply. Add a switch on the power supply to spare the Atari's built-in power toggle. Then use a common notebook power adapter. Might look a little funny with 2 bricks, unless the notebook adapter could fit inside the Atari brick.

Quote

Its an easy source of 3.3V, 5V and 12V for anything i need them for, and its more convenient then having a bunch of different bricks on my desk...

Ahh, I understand. I was thinking more along the lines of a dedicated 8 bit workstation rather than a multi-purpose arrangement like you describe.

I like the looks of the nicer Atari power supplies, especially the white XL units.

[BillC]

rdemming, on Sun Jan 22, 2012 9:21 AM, said:

griz, on Sun Jan 22, 2012 8:35 AM, said:

How about a Pico-PSU? Then again, at that price you may as well just get a real Atari power supply.

According to your link, the Pico-PSU needs a 12V input and not 110/220V. It provides a regulated 5/12V from any standard 12V DC source so you need an additional power adapter. And since it is ATX power supply, it needs some signals to turn it on/off. Just plugging in power does not make it switch on. So it is not really usable to replace a standard Atari power supply.

Robert

All it takes to get an ATX power supply to turn on is to short 2 pins together on the motherboard connector, that's how simple ATX power supply testers power them up without having a motherboard attached. A switch could be used to allow turning the power on/off as desired, but as already stated the high current such a supply can deliver means that traces could be destroyed if there is a short circuit.

Computer power supplies do fail as well, modern computers actually monitor +5V/+12V and will shut power off if they go too high, which is the reason the on/off signal is on the motherboard connector. I have seen ICs with the center blown out of them due to a failed power supply.