Introduction: Proximity Sensor With 2N7000 Mosfet
FET Proximity Sensor
This very simple proximity detector circuit will sense over 1 meter range with very few components. Output can be modified to drive a relay, power transistor or mosfet .
Step 1: For Maximum Sensitivity, R2 Should Be of a Large Value ( in the 1000 Mohm Range ) . You Will Have to Make It.
Step 2: You Will Need : 1) a Match 2) a Small Length of Wire. Wind Wire Tightly on Both Ends of Match to Form the Resistor. You Can Paint the Resistor With Clear Nail Polish to Protect From Moisture.
Step 3: Transistor Q2 Amplifies FET Current to Drive LED.
Step 4: Calibrate Potentiometer VR1 for Minimum Brightness of LED. Watch Video for More Details.
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Our circuit works but our result is inverted. LED on all the time but when a hand comes near the antennae the LED goes off. We used a Preset of same value instead of a POT. Is that OK?