[Amps] Auto tune conversion using stepper motors?

[Markku Oksanen]

Hi
Thanks for the ideas. 

Does anybody have a good idea how to find the "zero point" on vacuum cap without adding a potentiometer for position feedback?  I was thinking about reflective optical sensors and setting them up so that when the cap opens up totally, the gap between the sides of the capacitor are detected as a drop of reflection .  These sensors are really inexpensive, only thing is how to position them correctly and accurately.
Markku