Instructables

Cheap (AXT) Bench Power Supply 30 Amps!

Picture of Cheap (AXT) Bench Power Supply 30 Amps!
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This is my second PSU (Power supply Unit) as my prievieous one mysteriously burnt out (!)
I managed to purchace a new Computer PSU to convert, this one has a nice jucy 5V at 30A! and 12V at 21A!
I also managed to get a 30A panel Ammeter Yay!
Any comments welcome!
(Plz dun be too harsh lol)
Enjoy!
usafbrat1 year ago
How can you regulate the current, I dont want to blow up any of my components. Any where from (1-Max) amps. Please Help!!!
Vorpaxis usafbrat4 months ago

This is a belated answer but it doesn't seem to have been answered. You can use a current divider to regulate the current coming out of the PSU. Use a potentiometer to vary one of the resistances to get a variable current.

mikedoth4 years ago
Don't most home circuits only supply 15 amps?
Yes, 15 amps at 120 volts AC in the US anyway. Sometimes you will find 20 amp wall service, the outlet has a separate little tab cut into it to indicate.

For the rest of the world, check this page on wikipedia:

http://en.wikipedia.org/wiki/Mains_power_around_the_world

The thing is that the OUTPUT of the Power supply is not at 120 volts. So the amperage can be boosted as the voltage is dropped.

muttyfutty (author)  jhines00424 years ago
Sorry, lol I ment 'no' as in you didn't understand, not that home circuits dont provide 15A (actually its 13A for 240V and 15A for 120V (I think!)) but you can get larger ampage ones for cookers, ovens etc...
I knew what you meant, I was simply trying to help clarify your point. Nice instructable, btw. I will probably make one of these myself at some point.
muttyfutty (author)  jhines00424 years ago
Oh, Ok sorry lol thanks,I wish I documented the making so I could make a I'ble oh well, I'm currently working on a flyback driver, hmm...
Dude, you should post a link to your flyback driver. I'd like to check it out.
"So the amperage can be boosted as the voltage is dropped." How in the world is this possible?
This link has a great explanation of this exact principle.

http://www.allaboutcircuits.com/vol_2/chpt_9/2.html

Basically if you cut the voltage in half with a transformer you necessarily increase the amperage by a factor of 2. A mathematician would say they are dependent variables.
At 120V, a good power supply has a pretty good energy efficiency. Power = Voltage * Current (roughly speaking, there are some refinements needed for AC). Hence, 5V * 30A = 150 W, only ca. 1.3 A at 120 V, say a bit more because of inefficiency, still leaves things well-below the 15 A...
muttyfutty (author)  mikedoth4 years ago
No, Sorry I should have been more clear,
its 30A output
Quackoman3 years ago
the ammeter you found looks good but if the max out is 30A you should have gotten an ammeter that can read just above btw it looks very neat.
AngelLaHash4 years ago
Personaly i just got a light switch and hooked a ATX connection (24pin i think) to one end and 5v/12v on the other.. that way i figured i could use any ATX PSU i wanted. I love the Amp meter tho .. maybe write what connector is what on the case.
kiiko4 years ago
hehe cool, your tabel looks like mine ^^. lods of fun stuff
muttyfutty (author)  kiiko4 years ago
Haha!
I really need to tidy that mess up!
can't find my little snipper things...
pjharro4 years ago
Would you please be able to briefly explain your wiring? What do the lights do?

Thanks
muttyfutty (author)  pjharro4 years ago
Sorry for the late reply, I've been very buisy!
The Orange light is the mains on light
The large toggleswitch is the mains on/off
The red light is the system O.k indicator, it is connected to the 12V rail
And the small toggleswitch is the system on/off, it connects the Grey,green wires which have to be connected in order for the PSU to work.
Hope I helped!
                   Mike
bumsugger4 years ago
Looks good,any chance of a ctt. diagram,plus a few "build" details??
muttyfutty (author)  bumsugger4 years ago
well, Ctt diagram, hmmmm. all I did is just erm... hang on...
(removed by author or community request)
muttyfutty (author)  DELETED_bikedude8804 years ago
O.o ???