Update time. I've been working on a V2 that fixes many issues with V1.
Big ticket items include:
- digital control
- better voltage and overcurrent feedback
- discrete power stage
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.