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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Paul Patrakka High Current Power Supply Sunday, September 27, 2020 9:38:43 PM

For high current supply you can use microwave transformer ( secondary coil removed and recoiled for desired voltage ) with heavy wire and rectifier . For 14v power supply coil 10 turns of heavy wire , add high current rectifier and car audio capacitor like 1 Farad ...

ARXAIOS High Current Power Supply Monday, May 15, 2017 4:24:24 AM

First of all ..!! I made one like this and my opinion is this : do not build this one if you do not want to spend money on changing the power transistor because it will burn any time you draw sufficient current ..! Very bad circuit and with no protection ... The ripple is at the roof at high current . The transistor will be dead no matter what heatsink you out on it. Also this circuit is very very bad if your load are dc motors .! Instead of this OLD model of circuit you can use the safest way of putting a Voltage regulator with a power transistor on top of it with the current you want... Good Luck.

Billy High Current Power Supply Thursday, October 31, 2013 12:35:26 PM

I have bought up most of the components to build my power supple. Was wondering if you could tell me how to build my Bridge Rectifier and how to add a variable to my 70A 17V power supply. I have the transformer and caps. I think I need a 100A 100V Bridge Rectifier but finding one like that has proved to be very hard! Please if you can tell me anything about how to build what I need or let me know what mite work I would be very greatful! Also any info that may help like a scumadic etc would help a lot. Thanks Bill

anonymous JEFF High Current Power Supply Thursday, August 01, 2013 8:08:50 PM

I need a power supply schematic to build a 13.8vdc 20amp power supply. I was wonder if this one on this page would work for that or would I need to change compoint sizes. Thanks Jeff

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!

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Paul Patrakka	High Current Power Supply	Sunday, September 27, 2020 9:38:43 PM
For high current supply you can use microwave transformer ( secondary coil removed and recoiled for desired voltage ) with heavy wire and rectifier . For 14v power supply coil 10 turns of heavy wire , add high current rectifier and car audio capacitor like 1 Farad ...
ARXAIOS	High Current Power Supply	Monday, May 15, 2017 4:24:24 AM
First of all ..!! I made one like this and my opinion is this : do not build this one if you do not want to spend money on changing the power transistor because it will burn any time you draw sufficient current ..! Very bad circuit and with no protection ... The ripple is at the roof at high current . The transistor will be dead no matter what heatsink you out on it. Also this circuit is very very bad if your load are dc motors .! Instead of this OLD model of circuit you can use the safest way of putting a Voltage regulator with a power transistor on top of it with the current you want... Good Luck.
Billy	High Current Power Supply	Thursday, October 31, 2013 12:35:26 PM
I have bought up most of the components to build my power supple. Was wondering if you could tell me how to build my Bridge Rectifier and how to add a variable to my 70A 17V power supply. I have the transformer and caps. I think I need a 100A 100V Bridge Rectifier but finding one like that has proved to be very hard! Please if you can tell me anything about how to build what I need or let me know what mite work I would be very greatful! Also any info that may help like a scumadic etc would help a lot. Thanks Bill
anonymous JEFF	High Current Power Supply	Thursday, August 01, 2013 8:08:50 PM
I need a power supply schematic to build a 13.8vdc 20amp power supply. I was wonder if this one on this page would work for that or would I need to change compoint sizes. Thanks Jeff
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!