We found this circuit in a 1978 technical documentation. The circuit can be assembled with BC548 for Q1 and Q2 and BD136 for Q3. In place of the 9 V buzzer, you can supply the circuit with 12 V and use a relay for this voltage. In place of the 270-ohm R1 resistor, we can use a 10k potentiometer to work with sensitivity control. The LDR is of any common round type.
| Clique na imagem para ampliar |
