Three Simple Door Buzzer Circuits
Use low voltage so safe. I am boring old buzzer. When use AC line, danger of leakage power in the heavy rain, 3 circuits can help you!.. .......
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August 30, 2017
Simple Telephone Ring Amplifier circuits
The telephone repeater circuit or The call signal peripheral circuit to the loud than the original,with a buzzer or a electric bell, to increase loud sound
June 3, 2017