Wireless AC Main Detector (cheap)

wireless AC line detector
wireless AC line detector


  1. Resistants -100k (2nos.)
  2. Capacitor- 0.1 microferad (1nos.)
  3. common cathod display-lt543 (1nos.)
  4. IC – CD4033 (1nos.)
  5. wires ,probe , switch ,9-volt battery pack !
  • CMOS IC (CD4033) can be used to detect presence of mains AC voltage with the helpp of this circuit without any electrical contact with the conductor carrying AC current/voltage. Thus it can be used to detect mains AC voltage safely without tampering the wire. Just take it near to the conductor wire and it would detect presence of AC voltage. If AC voltage is not present, the display would be stable ( randomly show any digit (0 through 9) permanently). If mains AC supply is available in the conductor wire, the electric field produced would be induced into the sensing probe. Since IC used is of type CMOS, its input impedance is realy high and thus the induced voltage is sufficient to clock the counter IC. Thus display count advances or ascends rapidly from 0 to 9 and then repeats. This indicates presence of mains AC supply.

  • Display stops advancing clock wise when the probe is taken away from the mains AC carrying conductor.

  • For compactness, a 9-volt PP3 battery may be used for supply to the gadget

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