tracking resonance 1

[marcinLA]

I have a small tube/pzt transducer assembly that I want to put into resonance and lock in on a particular mode so that when changes in ambient occur the assembly will stay in that resonant mode. The mode occurs at ~2Mhz. Is there some kind of simple impedance analyzer/RF amp/phase locked loop-on-a-chip that would handle this task?

 

[Skogsgurra]

This is very similar to a crystal controlled oscillator. Just put the transducer in the feedback loop of an amplifier and it will usually start oscillating at its resonance frequency. You may need to limit the Q by putting some amplitude limiting in the circuit or use a safe power supply level.

There are usually two resonant modes; seies and parallel and you may need to decide which one you shall be running in. Different amplifier and feedback topologies give you either p or s resonance.

Gunnar Englund

http://www.gke.org

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