Peter's electronic projects

220V live wire-in-wall scanner


This little circuit will help you to scan the line of a 220V live wire in the wall. The FET gate is connected to a capacitive metal sensor (which is usually a simple metal plate). When you hold the sensor close to the wall, the LED will indicate the current flow around where it detects the wire. Works on 9VDC.

Schematic diagram

component value
R1 15M
R2 1.8k
R3 1M
R4 470
P 10k
D1 1N4148
D2 1N4148
component value
C1 2.2u
C2 100n
C3 22u
T1 BF244
T2 BC182B
T3 BC182B