I have been tasked with designing a piezoelectric actuator driver at its resonant frequency. This is to replace an arrangement where the sine wave source is a function generator chip (the obsolete XR-2206) that must be individually tweaked on a unit, by unit basis, to match the crystal’s resonant frequency.
The crystal is used as an actuator to vibrate a mirror used in a laser system. We have had systems come back from the field because the function generator’s sinewave frequency became too different for the system to work.
My idea is to use the crystal itself as part of an oscillator circuit so that frequency is always exactly the crystal’s resonant frequency. I have prepared an abbreviated concept schematic that can be viewed here:
RV2 adds energy to the crystal to sustain its oscillations. I do not know right now its optimum value.
U1 controls the oscillation amplitude by controlling the voltage on the op amp’s power supply lines. The circuit is designed to have a single supply so two regulators need not be ganged together.
I am aware there should be more capacitors in the U! adjustable regulator circuit, and ops amp circuits. U1 also needs protection diodes to prevent it being back driven in by capacitors during power down. All this has been removed for clarity.
U1 might have to be replaced with an adjustable DC DC Converter. I do not know right now how much current the crystal will require.
The cable to the crystal might be as long as five feet.
My questions are whether this should work in principle, and whether there are any bettor ways to do it.