RC networks may be used for the protection from switch bounce. The capacitor in the circuit filters the instant changes in the switching signal. When the switch is open, the voltage across the capacitor remains zero. Initially, when the switch is open the capacitor charges through both resistors. When the switch is closed, the capacitor starts discharging to zero hence the voltage at input terminal of the inverting Schmitt trigger is zero, so the output becomes “HIGH”. In the bouncing condition, the capacitor stops the voltage at Vin until it reaches Vcc. A diode was added to increase the speed of RC debouncing thus reducing the charging time of the capacitor.
