Call alertWe have designed this circuit, very simple indeed, which can be used in a sanatorium doctor, a college or school.
In the case of the sanatorium so that patients can call the nurses, in schools and colleges, so the director call the teachers of each section.
It consists of push buttons, diodes and capacitors buzzers, the latter two are the warning signs. I hope that it can be useful and you can find other applications.
C1, C2, C3: Electrolytic capacitors of 1000 µF. or more
D1, D2, D3: red LEDs
R1, R2, R3: 600
SW1, SW2; SW3: Pushers common type timbre
feed the circuit with a battery or power supply 9 volt.
pcb expensive components print