DIY Dual Power Supply LM350 Curcuit and PCB Layout

For most of my projects i need an external DC power supply, and because regulated power supplies are quiet expensive,

i will make my own, using LM350 linear voltage regulators.

Since the reference voltage of 1.25V is the same as the LM317’s, i will use the same circuit for the regulation.


To prevent short-circuit damage, i implemented a cut-off circuit which regulates the voltage down, until the current is lower than 3A.

Also, it will give the opportunity to switch from dual 3A to single 6A output.

The combined output will be regulated by both regulators in parallel, each still with their own 3A short-circuit protection.

Each output has  switch which enables me to avoid SC-protection, since the protection circuit has negative effects on the stability of the outputed voltage.


This is the curcuit:

LM350 Dual Power Supply Curcuit

 The potentiometers will be connected with the headers, so will be the switch (SW1&SW2)

SW1 and SW2 are one switch.


This is the PCB-Layout:

Download PCB Layout as .pdf


If you want the Proteus projectfile, feel free to send me an e-mail.


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