A project log for linear bench psu

24W linear PSU loosely based on EEVblog Usupply

LucasLucas 11/02/2020 at 07:070 Comments

Update time. I've been working on a V2 that fixes many issues with V1. 

Big ticket items include:

Firstly: digital control

I've realized how unfun it is to dial in the voltage with a multimeter, so i'm adding digital control. Nothing fancy, just a 16x2 LCD, two encoders, and an ATMEGA328. I'm having lots of fun teaching myself AVR.

Secondly, better voltage and current feedback

I've added a low pass filter to the feedback network to hopefully dampen oscillations. With the transistor pulling down the feedback network for overcurrent events, I could never get the stability I wanted. Instead, I moved to a differential amplifier. Don't know how it's more stable, but it works in SPICE.

Lastly: discrete power stage

Building a discrete power stage allows me to eliminate the negative supply rail needed to get below Vref on the LM350.

I've ordered parts and will post on the prototype soon. Enjoy a schematic.