El Cheapo 20A Lab Power Supply from ATX PC Supply

[SebastiaanLP670]

I've a normal PC power supply, and I want to make a normal supply to get energy from. can you tell me what I exactly need? So I can buy stuff in the stores? (like the types of resistors and stuff..)

thanks!

[m35a2lover]

i know you said you coulf run a transciever with that i have converted one for my cb radio and it works wonderful but i am however looking to get a new one with higher wattage i am going to add a very small linear amplifier and a frequency counter to my cb so i think the higher wattage will be better do you know where i could get a resistor similar to yours ?

[GeoN0JRJ]

@m35a2lover Sure. Try Mouser Electronics. They have all kinds of components. You might want to look at other plans for these power supplies and think about adding a 12v regulator IC. That way the load from an amp does not pull the voltage down. Watch the current draw from the amp to be sure you do not exceed the current rating of the Power supply. Let me know how it goes! Thanks for the post!

[GeoN0JRJ]

@m35a2lover You can order them from Mouser or digikey

[DanFrederiksen]

good build. maybe smaller load resistor would do as well (higher resistance)

what would be really interesting is to make the supply variable

[P1001AT2]

for anyone how is attempting this project and does not have a derivation of what wire is what just open the pcu follow the wires and it will tell which is which and also the wire that turns on the pcu.

[Imperiatus]

Loved the video! I'm going to put one together myself!

[tristan2668]

to get the orange 3.3V output working, all the orange have to be touching? Cause when I connect one orange to my dc motor then to the black ground wire, my psu turns off ?!?!?!? I want 3.3V going into my dc motor.

[EwOkiE2]

Hi at 7 mins into the video you installed a resistor.

Can you explain a bit more is it a Red + wire and a Black - Wire connecting it.?

Thanks..and excellent video!

[EwOkiE2]

If I get a PSU with these specs :

+12V 34A

+3.3V 28A

+5V 30A

-5V 0.3A

-12V 0.8A

+5VSB 3.0A

Would this be ok for a 12v 10A Digital Tyre Inflator ?

[GeoN0JRJ]

@EwOkiE2 Well, it is rated at 34A with all the 12v supply lines in parallel so I would say give it a try!

[xemphimtube]

you are a real GEM of a gentleman! great advice and clear instructional video. Great man!

[GeoN0JRJ]

Just a quick note that a large load, such as a transceiver, might pull the voltage down. I need to check this out and see what happens. If it does I will replace the existing voltage regulator for 12v side with one that can handle the added load; say a 30A regulator. There was also an article in the May 2002 QST called "St. Louis Switcher" This might yield some good ideas. If anyone else has ideas please share!

[khancock70]

Sir,

I actually have a few of these power supplies. How would you add the potentiometer and the meter to vary the output? 

[GeoN0JRJ]

@khancock70 I have not done this but one way would be to locate the Voltage reference chip on the secondary side of the Switching Power supply. Many of these supplies use a TL431 or similar chip. Once you find this, there should be a feedback resistor connected to one of the pins. In theory - I have not tried this so you are on your own - you should be able to connect across this resistor or remove and replace this resistor with a 1k potentiometer to adjust the voltage.

[GeoN0JRJ]

@khancock70 I have not tried that. I have seen some other PC pwr supply videos where they use a pot to vary the voltage. Just make sure it can handle the current!

[mukerjea]

Excellent advice for the power supply. In fact I was planning on buying one 12 volts power supply for one of my projects. You saved me some dollars. Thanks again.

[UmaBlinky]

I wonder if the fan would be adequite to load it instead of the resister?

[GeoN0JRJ]

@UmaBlinky That is an interesting thought. Just might do it. Although, the fan runs quiet now. THat might make it take off like a jet! LOL. Thanks for the comment.