How do I wire a three-terminal piezo buzzer to make it sound?

I salvaged a piezo sounder from a CO detector.  The sounder (EFM-290ED rated at 9V) has 3 pins rather than the two I am more familiar with.  The pins are labled G, F, and M.  I have tired applying 9V across all combinations of the pins but haven't had any luck maiking it sound.

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NdolaM2 years ago

I see your circuit says 9-20V. The test circuit uses 9V. With your circuit and 9V I'm getting very litttle sound (60 or 65 dB as a wild guess). Can you comment on how much volume you get with 9V? Thanks.

iceng NdolaM2 years ago

Though not the initial question. A strong volume comes from the resonating chamber where the piezo is held in place

NdolaM2 years ago

(I realize this is an old discussion, but in case you are still reading...)

I just tried 18V. Louder, but not enough to wake a teenager. Maybe my EFM-290ED is damaged.

iceng4 years ago
Try the 2N2222 version.

3t piezzo.gif
Great for getting a teenager out of bead in the morning.
Needs a oscillator to M (main) and G(ground)
F (feedback) is for a feedback oscillator.