Probe for live electrical wires beneath decorations - has transistorized amplifier connected to LED and responsive to electrical field via screw driver blade acting as aerial

摘要

A proble detects the position of live electrical wires concealed beneath decorations. A hand-held housing contains a power supply (25) connected by a switch (12) to a transistorized amplifier stage with an indicator. The input of the amplifier stage is connected to an antenna (3). The housing may be the hollow handle of a screwdriver, in which case the blade is used as the antenna. The power supply is pref. a dry battery and the indicator is pref. a light emitting diode. The amplifier stage pref. comprises a single m-channel field effect transistor (21).