High Current Power Supply

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Since my page was first posted, I have received a number of emails asking about a high current power supply. I looked around, but couldn't find one that was suitable. So, I designed this. It is a linear supply, which might have a few of you rolling your eyes, but it takes very few parts, is simple to build and can supply huge currents.

Schematic

Parts

Part	Total Qty.	Description	Substitutions
R1	1	680 Ohm 1/4 Watt Resistor
C1	1	20,000 - 50,000uF 20-40 Volt Capacitor
C2, C3	2	100uF 50 Volt Capacitor
C4	1	0.1uF 50 Volt Capacitor
C5	1	0.01uF 50 Volt Capacitor
D1	1	Zener Diode (See Notes)
Q1	1	2N3055 Or Other (See Notes)
T1	1	Transformer (See Notes)
BR1	1	Bridge Rectifier (See Notes)
S1	1	SPST 250 VAC 10 A Switch
MISC	1	Case, Line Cord, Heatsink For Q1, Binding Posts For Output

Notes

D1 should be rated at about one volt higher than then desired output of the supply. A half watt diode will do.

Q1 can be a transistor similar to the 2N3055. I chose the 2N3055 for it's availability and power handling (150 watts).

T1 should be about 5 volts higher than the desired output of the supply, and rated for about one amp more of current. The voltage overhead is required by the regulator section. The extra current is to keep the transformer from over heating.

The choice of BR1 will depend on the voltage and current of your transformer. The rectifier should be rated for 50 volts more than the transformer, and 5 amps more than the transformer.

The value of R1 will be smaller when supplying high currents. Expiriment until you get what you need.

You are going to need to heatsink Q1 and BR1. Use a small PC case style fan unless you are going to run large heatsinks.

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Comments

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jeans High Current Power Supply Tuesday, July 17, 2012 10:23:36 AM

Hello, I wonder how to get high current with this configuration? Lets take the highest hfe for this transistor, 70. With 12Dc and a resistor of 680Ohm result a current from 17mA x hfe 70 = 1,235 Amps??

anonymous High Current Power Supply Wednesday, December 14, 2011 5:56:55 PM

he requests for specific "I need to do this" stuff leads me to this conclusion: Put the soldering iron down and step away and nobody gets hurt

anonymous High Current Power Supply Saturday, September 24, 2011 10:51:29 AM

i want to make a 12 volt 40 ampere power supply for a very urgent project. please send me any info regarding that

John B High Current Power Supply Monday, March 22, 2010 12:06:28 AM

I have components for electrifying my bike. Is it feasable to use this PS, substitute a 12v 15A motor for the transformer and get my power for the motor and battery buffer? What other suggestions do you have?

peterlonz High Current Power Supply Friday, September 04, 2009 12:30:00 AM

Looks like a low cost easily built cicuit BUt it's design concept is for a fixed output. I would very much like to see a variable 5A (or greater) in the range say 2 to 48V . I am unable to "modify" your circuit to achieve this with a pot which anyway would involve switching to different resistance sub circuits - I thnk!! The best type of variable is the infinitely variable which requires generally a digital voltmeter to be incorporated & this adds COST unless you have a low cost design for a digi-voltmeter???

anonymous High Current Power Supply Friday, August 21, 2009 3:26:03 AM

Thank you for your circuit!

paddyB 48 volt supply Friday, May 08, 2009 9:29:22 AM

Hi. Very interesting reading. My problem is that I have built an 8 channel microphone unit and need a 48 volt power supply - each mic needing around 4ma. Any ideas ??

anonymous High Current Power Supply Saturday, April 11, 2009 7:35:57 AM

Your circuit is simple and good. Series voltage regulation has a high ripple and poor regulation compare to one which are using a 7812 regulator. I want to make a power supply that is capable to higher currents. But 7812 has a maximum current of about 1.5A, how can i incorporate this with your circuit? Please send me your comment and please include the circuit so that i can fully understand your circuit. I know that making a complex circuit could make me understand well. Thank you. Efren,

anonymous High Current Power Supply Thursday, April 09, 2009 2:22:25 PM

ROFLMAO @ Captain electrode! Yeah man, you can TOTALLY build a 16kw power supply for $40. For god's sake, if you have so little knowledge about electricity and electronics to even ask that question you should NOT be anywhere near high voltage or high current, you are a danger to yourself and others! PLEASE PLEASE PLEASE read a book or two about basic electric theory or EM physics so you don't hurt yourself OR SOMEONE ELSE! Or cause a citywide blackout, for that matter! Good luck man!

anonymous High Current Power Supply Monday, March 02, 2009 7:58:28 PM

If you correct at Note 2, from 150W to 150mW, everything is going to be O.K.

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jeans	High Current Power Supply	Tuesday, July 17, 2012 10:23:36 AM
Hello, I wonder how to get high current with this configuration? Lets take the highest hfe for this transistor, 70. With 12Dc and a resistor of 680Ohm result a current from 17mA x hfe 70 = 1,235 Amps??
anonymous	High Current Power Supply	Wednesday, December 14, 2011 5:56:55 PM
he requests for specific "I need to do this" stuff leads me to this conclusion: Put the soldering iron down and step away and nobody gets hurt
anonymous	High Current Power Supply	Saturday, September 24, 2011 10:51:29 AM
i want to make a 12 volt 40 ampere power supply for a very urgent project. please send me any info regarding that
John B	High Current Power Supply	Monday, March 22, 2010 12:06:28 AM
I have components for electrifying my bike. Is it feasable to use this PS, substitute a 12v 15A motor for the transformer and get my power for the motor and battery buffer? What other suggestions do you have?
peterlonz	High Current Power Supply	Friday, September 04, 2009 12:30:00 AM
Looks like a low cost easily built cicuit BUt it's design concept is for a fixed output. I would very much like to see a variable 5A (or greater) in the range say 2 to 48V . I am unable to "modify" your circuit to achieve this with a pot which anyway would involve switching to different resistance sub circuits - I thnk!! The best type of variable is the infinitely variable which requires generally a digital voltmeter to be incorporated & this adds COST unless you have a low cost design for a digi-voltmeter???
anonymous	High Current Power Supply	Friday, August 21, 2009 3:26:03 AM
Thank you for your circuit!
paddyB	48 volt supply	Friday, May 08, 2009 9:29:22 AM
Hi. Very interesting reading. My problem is that I have built an 8 channel microphone unit and need a 48 volt power supply - each mic needing around 4ma. Any ideas ??
anonymous	High Current Power Supply	Saturday, April 11, 2009 7:35:57 AM
Your circuit is simple and good. Series voltage regulation has a high ripple and poor regulation compare to one which are using a 7812 regulator. I want to make a power supply that is capable to higher currents. But 7812 has a maximum current of about 1.5A, how can i incorporate this with your circuit? Please send me your comment and please include the circuit so that i can fully understand your circuit. I know that making a complex circuit could make me understand well. Thank you. Efren,
anonymous	High Current Power Supply	Thursday, April 09, 2009 2:22:25 PM
ROFLMAO @ Captain electrode! Yeah man, you can TOTALLY build a 16kw power supply for $40. For god's sake, if you have so little knowledge about electricity and electronics to even ask that question you should NOT be anywhere near high voltage or high current, you are a danger to yourself and others! PLEASE PLEASE PLEASE read a book or two about basic electric theory or EM physics so you don't hurt yourself OR SOMEONE ELSE! Or cause a citywide blackout, for that matter! Good luck man!
anonymous	High Current Power Supply	Monday, March 02, 2009 7:58:28 PM
If you correct at Note 2, from 150W to 150mW, everything is going to be O.K.