Video Activated Relay

input = video input

R1, R2 10K 1/4 W Resistor
R3 1K 1/4 W Resistor
R4 33K 1/4 W Resistor
C1 1uF Electrolytic Capacitor
Q1, Q2, Q3 2N2222 NPN Transistor 2N3904 NPN Transistor
D1, D2, D3 1N4148 Diode
K1 9V Relay
J1 RCA Jack

Notes:
1. Since you may be using this circuit to switch mains voltage, it should be enclosed in a case.

2. The circuit will also work with most line level audio, although you may have to adjust the value of R1