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I'm looking to hook up a piezoelectric PZT to a microcontroller that will be providing a white noise signal. However, the 5ish volts that the microcontroller can spit out isn't strong enough to vibrate the PZT as energetically as needed. Experiments have shown that a signal with 25 volts is the minimum needed (the PZT can handle voltages up to 300V) for the purpose.

The whole experiment is in a limited amount of space and (for now) run by several 9 volt long-life lithium batteries hooked up in parallel. Given those constraints on space and power, what is the best device, or at least the best category of devices for this job? If "nothing" is the answer, how best can I rearrange the batteries to provide for an alternative?

I don't mind having to assemble a few things together, but if the problem could be solved with one circuit or device, that would be ideal.

Thank you for your time and brain power. If I'm missing any vital details, I'll do my best to supply those upon request.

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Recently faced the same problem driving a piezoelectric speaker.

Solution: Use a miniature audio output transformer... we selected the Hammond 104R, ~ US$20 per unit.

Hammond Audio Transformers

The cube in the middle is the Hammond 104 series (0.71 x 0.86 x 0.75 inches), rated for 500 mW. If power output requirement is under 100 mW, the truly miniscule Hammond 101V might be a better option (0.45 x 0.45 x 0.48 inches).

Connection:

  • High impedance side drives piezo
  • Low impedance side driven by op-amp as buffer / voltage follower
  • Buffer input driven from the microcontroller output.

Note that the transformer is used with the primary and secondary switched, compared to typical audio output transformer implementations where the low impedance side drives the speaker. These transformers are optimized for use in either direction.

Much cheaper alternative transformers are available, down to about $2 each, if weather resistance is not essential. These particular units are potted, and practically anything-proof, something we needed for our design.

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