How does the Circuit Function?
By referring to the circuit schematic we can see that the whole circuit is wired around the IC 324, which is a package of 4 op-amps or quad op-amps.
It forms the heart of the circuit. One of its op amps, A1, is configured as a high gain current to the voltage converter and the second one, A2, is used as a buffer to produce a stabilized output on detection of an AC signal.
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The moment the antenna of the circuit is taken near a conductor carrying AC, the vibrations around the conductor are immediately picked up. These tiny alternating vibrations induce a corresponding current ripple into the circuit, disturbing the overall stability of the circuit.
These input disturbances are instantly amplified by A1 and converted into an output voltage equal to the peak supply voltage of the circuit. The out put is fed to the next amplifier stage via capacitor C1.
On receiving the pulse, A2 further amplifies the signal to produce a visual indication, showing the presence of an AC phase, and vice versa.
The value of R2 may be increased or decreased to correspondingly increase or decrease the sensitivity of the circuit.