The circuit can be used in variety of projects where AC detection is required. A relay switch is used at the output of the circuit that can be connected to AC and DC equipments. The can also work to deactivate an equipment when AC is preset, this can be done simply by using other normally open points of the relay.
The heart of the circuit is a LM358 high gain amplifier. The circuit drains very low power and in stand by mode, it only consumes around 0.5mA. The operating voltage is 9V to 12V DC. The sensitivity of the circuit can be adjusted with 1M variable resistor. The sensitivity also depends on the lenght antenna wire; increasing two to three inches will increase the sensitivity more.
This contactless AC mains detector relay switch circuit will activate a relay switch when an AC voltage is presents in main lines and deactivates it when AC voltage is not present there. There is no need to making any contact with the mains because the circuit senses the electric filed around the mains wires.
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