Simple Circuit With One Mosfet to Control Lamp Using Proximity Switch or Limit Switch or LDR (light Dependant Resistor)

This simple circuit can control a lamp using proximity switch or a limit switch or an LDR . The circuit uses a single mosfet, a resistor and a relay for this purpose.

1. Mosfet IRF840 1 no.
2. Resistor 1kohm 1 no.
3. Relay SPST type 1 no.
4. 12V DC power supply 1 no.
5. Proximity switch 1 no. (or limit switch or an LDR)
6. Bread board 1 no.

The circuit is tested and found functioning correctly.

The circuit uses a mosfet, a resistor and a relay as the three components to control a lamp.

The circuit is compatible with proximity switch or a limit switch or an LDR. Inputs from any of these items can be fed to the circuit to trigger a lamp.

1. Proximity switch: When this is connected to the circuit with no metal object present, the voltage between mosfet gate and source is zero. When metal object is present, the mosfet gate to source voltage is > 5V thereby switching the relay ON. Watch the video Proximity switch interfacing with a mosfet and controlling a relay. Controlling a lamp 230v AC - YouTube
2. Limit switch: Instead of proximity switch, limit switch is connected. The circuit function is same. Watch the video Limit switch interfacing with mosfet and controlling relay and 220V AC lamp - YouTube
3. LDR(light dependent resistor): The circuit function is same. Watch the video Limit switch interfacing with mosfet and controlling relay and 220V AC lamp - YouTube