Bidirectional millivolt source

by VladM

6 parts

A Pot across ±3 V picks a voltage between the rails, unity-gain follower buffers it, and a 19 kΩ / 1 kΩ divider scales it by 1/20, so the tap swings about ±147 mV: a small bipolar test voltage you can set by hand on the Pot. Saved at 75 %: +1.5 V at the wiper, +75 mV at the tap. This is to mimic into any IC that wants to see - to + mV as an input.