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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.

Build

Notes

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.

Construction

Breadboard

Schematic

Build

Results

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..

output

Credits and References

About LEAP#596 OscillatorsCrystalAudio

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