Current Flow Indicator

With this simple circuit, you can confirm the flow of current through AC wires without touching the hot wire. It is an ideal circuit to monitor Laptop charger, Battery charger etc. It is also useful to check the flow of current in concealed cables. The circuit gives an LED indication from a distance of 15 cms if current is flowing through a live wire.

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Only one IC can do the job. CD 4093 is the 7 segment decoder cum driver IC used to drive 7 segment display. Its input pin 1 is highly sensitive and can readily accept the 50Hz electromagnetic pulses present around live wires.

At power On, IC resets through C1 ,R1 and goes to standby mode. When the antenna ( it can be a small piece of plastic wire with insulation) is close to the live wire, outputs of IC1 ( it has 10 outputs) goes high one by one with each pulse in its input. This keeps the LED blinking. C2 act as a buffer capacitor for the steady glow of LED.

CD 4093 works off 5 volts, so two 3 volt lithium cells or 6 V mini battery can be used as the power source.

D1,D2,D3 are IN4148 Diodes

Keep the circuit close to the live wire that is to be monitored. You can use the case of an old tester or big marker pen to enclose the circuit.
Note: Do not touch the antenna to the bare points of wires or the AC socket. A distance of 15 cms from the wire is sufficient to give indication.

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