Posted on Feb 5, 2014

The circuit depicted here forms one half of a device that will prove extremely handy when tracing the path of electrical wiring in a building or to locate a break in a wire. The system is based on similar equipment that is used by technicians in telephone exchanges. The operation is straightforward. You require a generator that delivers an easily

Click here to download the full size of the above Circuit.

recognizable signal which, using a short antenna, is inductively coupled to a simple, but high gain, receiver. To create a useful transmitter it would suffice to build a simple generator based on a 555. But as the adjacent diagram shows, a 556 was selected instead. The second timer (IC1a) is used to modulate the tone produced by IC1b. The output frequency alternates between about 2100 Hz and 2200 Hz. This is a very distinctive test signal that is easily distinguished from any other signals that may be present. Resistor R6 is connected to a piece of wire, about ten centimeters long, that functions as the antenna. The ground connection (junction C2-C3) is connected to ground. When the antenna is connected directly to a cable, it is possible to determine at the other end of the cable, with the aid of the receiver, which conductor is which (don`t do this with live conductors!). The schematic for the matching receiver may be found elsewhere in this website.

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    Audio signal Indicator
    Quiz Circuit
    Electronic Horn
    Auto gain Control op-ampCircuit
    Data Based Voltage Controlled Amplifier
    decoder circuit
    Design a esthetic and energy-conserving acousto-optic controlled lighting lamp of corridor
    40 PIN AVR Development Board
    Electronic Siren
    12v 10 minute Off-Delay timer
    Basic current to voltage converter
    Simple VHF FM radio
    Current sensing of the rails circuit diagram
    Auto-voltage starting time relay control circuit