Could anyone point me to a good, or even awesome circuit schematic using the 2n2222a transistor in an audio amp for a piezo buzzer disk contact microphone? I intend to use it to capture and listen to human speech.



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  • \$\begingroup\$ What are the properties of the piezo buzzer disk contact microphone? Rout, Cout, resonances, bandwidth, etc. \$\endgroup\$ – analogsystemsrf Jan 5 at 5:52
  • \$\begingroup\$ You mean like beep when anyone talks? using the piezo as a mic and a beeper? How novel. Same idea can be used as a motion detector for security goods with a ball bearing inside. \$\endgroup\$ – Sunnyskyguy EE75 Jan 5 at 8:58
  • \$\begingroup\$ um, aren't you restricting yourself a little much? wouldn't it be much easier to just build a piezo microphone amplifier with the components of choice (and glue a 2N222A on it when it's done to have the 2n2222a integrated there)? \$\endgroup\$ – Marcus Müller Jan 5 at 9:04
  • \$\begingroup\$ @TonyEErocketscientist like the man Fletch said, it’s all ball bearings these days... \$\endgroup\$ – Francis from ResponseBase Jan 5 at 19:43
  • \$\begingroup\$ I pulled the buzzer from a household fire, and have no specs for it. \$\endgroup\$ – Francis from ResponseBase Jan 5 at 19:45