Four switch alarm system.. very simple using one npn transistor

140

02:44:36

Put each switch on a door or Window and when there opened the light will turn on. Or you can replace the led with a buzzer

published 9 years ago

danwood

8 years ago

Hi, can i swap the led for a piezo?

danwood

8 years ago

How can i modify the circuit to take a 12v battery to power a loud siren? Will i need to change other comonents? And i want to put a switch in to disarm the ciruit when required too.. thanks

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