Infrared (IR) Proximity (Distance) Sensor

The photodiode can be used to detect IR reflected from the object. However, IR produced by the ambient conditions also detected by the photodiode. This IR noise must be filtered to prevent false detections. Usually, the LED’s IR signal is modulated with a convenient frequency and then using that modulation to detect only IR to filter the IR noise. So, […]

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Temperature-Compensated Capacitive Proximity Detector

This is a circuit of Temperature-Compensated Capacitive Proximity Detector. it will lights the LED when a person approaches the antenna plate. Here is the circuit : The 4-inch-square antenna plate and a 33pF capacitor (C1) in parallel with 15pF (6 inches of coaxial cable at 30pF per foot)  are used to form delay capacitance of this circuit. It charges to […]

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