Скачать или смотреть Uses for piezo transducers from old smoke alarms

Old smoke alarms often have piezo transducers in them. Here's some uses for them in electronic projects.

Contents
0:00 Introduction
1:13 Test with audio amplifier
1:48 Test with LED connected
2:31 Use as a speaker - how good?
4:07 Use as a selective speaker for CW
4:43 Use with a crystal set
5:11 Audio oscillator
6:05 Summary

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