Omishra PSU - mods for high current requirement

[rbalu72]

I have few Omishra PSU boards populated and would like to draw more than 1.5A current from the output points.

What all mods required to achieve this?

I would like to put 18-0-18, 5A as input and obtain about 0-25v dc, 5A and 10V-0-10V to drive a pre from the same board.

Please, can someone suggest? Attaching OPS Manual for reference.

Thanks,

 

[manniraj]

@balu, I had a chat with Omishra/Sachin last year for the same need especially to build a VFM LPSU for the Pi3 which needs 5V 2.5A for good performance. As per them with the LM317/337 regulators I think the max current handling can be only 1 to 1.25A max. So I think the regulators are the bottleneck to achieve higher current. I did use small TO-220 heat sinks on them for my DAC build initially but that was less than 500mA.

 

[rbalu72]

Thanks Ramesh.. that helps.

 

[surfatwork]

Check out lm137 and lm138. You will need a pass transistor for the 137. Lot of circuits on the net, and it should not be too difficult to adapt omishra's pcb.

 

[saikatbiswas82]

Go for LT1084/1085 if you need regulated power for RPI.

 

[spirovious]

I have found LM338 similar to LM317 and it supports 5amp current.

 

[omishra]

There is newer PCB which will make this mod easy or go for capacitance multiplier board. Ask Sachin for both of them.