Diy Regulated Power Supply 12v , 5v And 3v From Pc Psu

jstarne1

USA

Hello EZ Robot members. I came up with the idea to post this mini project because my roommate needed a power supply to power leds and also 12v fans. Lots of members really need a good high amp dc bench power supply on a budget. My roommate went to a local electronics supplier and recently paid 90 dollars for a 7amp 12v DC power supply. Pc power supplies are generally reliable , handle 15 to 40 amps DC and are 1/5 the price. Take for example the Thermaltake 425 watt TR2 for 30 dollars at Best Buy in the USA.

Safety alert! Capacitors in psu can pop you pretty hard so avoid touching internals of a pc psu even when its not plugged in.

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#17  

i have a p4-350w what is the minimum load for it to power up when i connect ps_on with gnd it makes some noise then turns off when i pulse ps_on with gnd fast i have around 3v on 12v rail bad output but when i disconnect ps_on i have solid power on 5v standby please help thanks

#18  

@khudo , its a switching power supply. It can power on with zero load. You will want to ground the green wire. Use the normal on and off switch to power it on and off. If it doesn't have one add a regular toggle switch to cut the 110v ac power.

#20  

MOST power suppy does need a 5 ohm load on the 5 volt line or wont stay stable or stay on

look at the breakout board by sparkfun it uses 20 ohm load at 2 watts for the 5 volt line

atx breakout board schematic