Or is there any issues I should be wary of? I need at least 7A on a 12V line, but I've found that a computer PSUs are significantly cheaper.
\$\begingroup\$
\$\endgroup\$
Add a comment
|
2 Answers
\$\begingroup\$
\$\endgroup\$
3
Yes.
There's not much more to say than that ;)
Getting them to turn on though can be a bit tricky. Some may require a load on the 5V before they will allow you to turn them on (a simple resistor will do), some may require the load on the 12V (in which case you're fine), and some don't care either way.
To switch a normal ATX power supply on you need to connect the green wire to ground. I often use an NPN transistor to act as an MCU controlled switch to control the power.
I have a small one embedded in my desk powering all sorts of things - PIC32s, audio amplifiers, a bunch of binding posts for powering whatever I'm working on... It's a really handy power source, The -12V is also great to have available.
-
\$\begingroup\$ It does seem like an attractive alternative. I just didn't get the green wire bit. I was planning to use just 12V and Ground to power a couple of DC regulators, can't I just use a common ground line on everything (connected to the green wire)? \$\endgroup\$ Commented Oct 13, 2014 at 16:09
-
2\$\begingroup\$ @joaocandre - As far as I know, the green wire is a signal line. It is an electronic switch that turns on the PSU when driven low. People usually wire it directly to ground, but you could have a button to control it. It doesn't have to do with power GROUND or the EARTH green wires used as standard in some places. \$\endgroup\$– RicardoCommented Oct 13, 2014 at 16:23
-
\$\begingroup\$ Yes, the green wire is the "power on" signal, which is active low. A simple switch on it to connect it to ground would suffice as a master power switch, or just short it direct to ground to have it always powered on. BTW, orange is +3.3V, red is 5V, yellow is +12V and (usually) blue is -12V. Purple is standby power (+5V) which is always on even when the power is "off" (it's used to power the power control circuits, WoL, etc, on a motherboard). \$\endgroup\$– MajenkoCommented Oct 13, 2014 at 17:12
\$\begingroup\$
\$\endgroup\$
Well you may find some other surplus options, but otherwise, as long as the output amp rating of the PS is enough for what you need, it may work. I'll caution you though that I've observed very poor regulation on everything but the lower voltage (5V, 3.3V, 2.2V) outputs, which MUST be very precise. The 12V outputs are often used for the motors in disk drives, whose speed is precisely controlled by the drives themselves, and therefore don't need a well regulated power source.
