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This is a driver for a pulsed piezoelectric buzzer. The upper 555 sets the pulse interval, and the lower the audio frequency. The circuit as built will run a 9V piezo speaker (modeled as the resistor and cap on the right) at 30kHz for 5 seconds every 15 seconds. The astable (lower left) cap on the lower 555 determines the piezo frequency. Use a higher value cap for a lower frequency (i.e. 10nF = 3kHz). The circuit expects 2n3904 transistors, but 2n2222's will likely work.
If the simulation chokes, try increasing the astable cap to 1 uf or so.
Please note that piezo speakers have resonant frequencies, so choose accordingly. I used a speaker from an ultrasonic pest deterrent purchased at a home improvement warehouse store.
Since this is an ultrasonic circuit, I included an indicator LED (at the far right of the circuit). This is of course optional (LED and control resistor). If you remove the LED, you can replace the 3.3k resistor feeding the lower NPN with a 5.6k (it'll save a bit of power).
With an off-the-shelf 9V battery, this will run for 40+ hours (without the LED). An energizer industrial would last 80+ hours.
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