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Project Notes

#596 OpAmp Piezo Driver

Testing a circuit for driving a piezoelectric transducer for sound output with a TL072 opamp oscillator.



As discussed in LEAP#455 Piezo Transducers and Buzzers, piezoelectric transducer require an external oscillator to produce sound.

This is an example of an OpAmp driver:

  • comparator-based relaxation oscillator implemented with one OpAmp from a TL072
  • 2N7000 switch to enable the oscillator
  • driving a passive buzzer element

NB: I have seen silimar circuits with an NPN BJT switch but some of these don’t seem to turn the oscillator hard enough off.






Works fine - emits a constant tone when the button is pressed.

A crude estimate just considering the 20kΩ and 10nF RC path suggest a frequncy ~796 Hz. Actually 844Hz acording to the scope..


Credits and References

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This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of projects. Two main themes have emerged in recent years, sometimes combined:

  • electronics - usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting
  • scale modelling - I caught the bug after deciding to build a Harrier during covid to demonstrate an electronic jet engine simulation. Let the fun begin..
To be honest, I haven't quite figured out if these two interests belong in the same GitHub repo or not. But for now - they are all here!

Projects are often inspired by things found wild on the net, or ideas from the many great electronics and scale modelling podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know (or send a PR!). See the individual projects for credits where due.