Simplest door alarm circuit

311

03:50:03

This circuit uses a SPDT magnet switch to charge the capacitor through the battery and discharge it through the base resistor on the npn transistor.

Visit project page https://delphijustin.biz/simple-doorbell-alarm/

published 2 years ago

mlira

2 years ago

If you use a MOSFET the current draw on the capacitor will be a lot less and it won't need to be as big. Either that or simplify it further by using a spst switch from the power supply to the gate of the MOSFET directly (and have the buzzer connected straight to the supply).

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