This is a simple proximity switches with IC 4049th The IC4049 is a bipolar monolithic integrated circuit for use in metal-detection system / proximity sensing applications IC4049 includes an oscillator constituted by an external parallel resonant tank circuit and a feedback resistor connected 2-5 The internal oscillator operates near the resonant frequency of the tank is brought circuit.As a metal object near the coil begins to decrease the amplitude of the voltage across the tank gradually.
If the envelope of the oscillation a certain level, the greater the resistance the greater the travel distance.Detection-point range with a high Q coil.Maximum possible range can be achieved with a well extended to 1-inch drive circuit. Only So this circuit, the tuning circuit to a certain range.
For making it easy to a metal coil at the desired distance (1 inch) square and adjust the resistance, C1 and C2 (make Pin2 or 5) one of the outputs in the state change.
