Variable power supply design Help

[zio_nneo]

I have 12V/5A fixed Dc source. How Can I get the variable power supply from this. I had tried one that uses the LM 317 IC but it does not work it is because its current handling capacity is only upto 1 to 1.5A. Now Can anybody help on designing the variable power supply thats output voltage can vary from 0 to 12V and maximum current is 5A. Note that this supply should be made from available fixed 12V/5A supply. Thanx in advance

 

[hr_rezaee]

Hi
I think you can increase the current to 3A in your case.
you can parallel two or more LM317 to gain access more current.
But, see the datasheet, there is special method for parallel. don't parallel them directly because this can damage one of LM317s.
regards

 

[zio_nneo]

Yes I had made plan for that too. But I am scared how to operate them in parrel configuration. Is it possible to connect them in parallel.If anybody help me for this.

 

[necolei]

Yes I had made plan for that too. But I am scared how to operate them in parrel configuration. Is it possible to connect them in parallel.If anybody help me for this.

Don't be afraid to experiment or don't be afraid to lose some IC's. If you know that you are doing the right thing then trust yourself. Here is some suggestions on increasing the output current "use a high power NPN or PNP transistor and connect it with your LM317 then you have a high current variable power supply. That's a clue.

 

[rkodaira]

Use LM350 the 3A equivalent of LM317