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Contactless
AC Mains Voltage Detector
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is a CMOS IC (CD4033) based circuit which can be used
to detect presence of mains AC voltage without any electrical
contact with the conductor carrying AC current/voltage.
Thus it can be used to detect mains AC voltage without
removing the insulation from the conductor. Just take
it in the vicinity of the conductor and it would detect
presence of AC voltage. If AC voltage is not present,
the display would randomly show any digit (0 through 9)
permanently. If mains supply is available in the conductor,
the electric field would be induced into the sensing probe.
Since IC used is CMOS type, its input impedance is extremely
high and thus the induced voltage is sufficient to clock
the counter IC. Thus display count advances rapidly from
0 to 9 and then repeats itself. This is the indication
for presence of mains supply. Display stops advancing
when the unit is taken away from the mains carrying conductor.
For compactness, a 9-volt PP3 battery may be used for
supply to the gadget. |
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