High Current Power supply

[cswilson]

I'm looking to build a constant current power supply 1.5-2.4V with adjustable current from low to 30amps(possablility to modify it later for up to 70 amps
I would prefer if it used LM338 as I have many with large heat sinks already.
I intend to use this to drive a bar Laser diode

I have seen a few simple circuits but am a little rusty on how well they would work, nor how to make them adjustable current(if they aren't already)

With the above image I could add 3 more LM338's in parrallel to get to 30A
anyone know how I can modify this so that I can have adjustable current.

 

[BradtheRad]

A transistor is a constant current device, if you provide it with a stable bias.

Screenshot of my simulation:



A darlington arrangement was used so as to reduce current in the potentiometer.

A slider (offscreen) varied the supply between 1.5 and 2.4V.

The load is your laser diode. It receives 73.3 A at all times. I gave it 1 V forward spec.

The transistor must drop the excess voltage. It will need to dissipate up to 93W of heat.
A gang of multiple transistors in parallel may be required.

This method may or may not adapt to your desire to use LM338 IC's.

 

[pplus]

Look at this chart. Regarded as an idea, it can be combined with the selected you.

 

[tpetar]

See this switcher project, maybe you find something useful for you. You can adjust voltage and current to your needs.

**broken link removed**



One LM338K can handle 5A continuous, this is my favorite power voltage regulator, and I'm very satisfied with this regulator, but price of whole device with many LM338K can be expensive, better change look on things.