Logic Gates may be used to remove oscillations or unwanted pulses (bouncing) produced by mechanical switches and relays during the mechanical switching process.  Below is an example of a switch debouncing circuit that utilizes NOR gates.

Figure 1. Bounce-free Mechanical Switching with NOR Gates

Figure 1 shows a circuit that uses two NOR gates to stabilize the output of a mechanical switch or relay. The output of the circuit as shown is '0'. Thus, at this point, X1 is '0'.

When the switch is thrown from '0' to '1', the 3.3 k-ohm resistor pulls up Y1 to '1', causing the output of NOR A to switch from '1' to '0'. This also causes X2 to go to '0'. However, the output of the circuit (which is the output of NOR B) remains at '0' until the instant the mechanical switch pulls Y2 to ground. Once this happens, both X2 and Y2 will be '0', causing the output of NOR B to go to '1'.

At this point, X1 also goes to '1', keeping the output of NOR A at '0' and the output of NOR B at '1'. In effect, the switching action of the mechanical switch was transformed by the two NOR gates into a clean digital transition from '0' to '1' at the circuit's output.

Throwing the mechanical switch back to '0' causes Y1 to go to '0' and Y2 to go to '1'.  This causes the output of the circuit (output of NOR B) to go to '0'. This causes X1 to go to '0', which forces the output of NOR A to go to '1' since Y1 is also '0' at this point. The change of NOR A's output to '1' stabilizes the output of the circuit at '0'. Again, the mechanical switching action was transformed by the circuit into a clean digital transition from '1' to '0'.