Switch Contact Bounce: One Mechanical Operation Can Produce Several Electrical Edges

Observe the electrical event

Analog Devices describes contact bounce as repeated open-close transitions before a mechanical switch settles. A digital receiver can interpret those transitions separately. Primary reference: switch bounce.

The intended human or mechanical operation and the raw electrical edge count are therefore different records. Preserve the waveform and the receiver’s acceptance rule. An apparently excessive count can be investigated without assuming multiple physical operations or one confirmed hardware failure.

A fictional trace and rule

Imagine one hypothetical press produces low-to-high edges at 0,2 and 5 ms, with the signal then remaining high. A receiver that counts every rising edge records three. A separate illustrative rule accepts a change only after the new state remains stable for 10 ms.

Under that rule, the final high state would be accepted at 15 ms in the ideal trace. It would represent one logical transition. The 10 ms rule is invented to explain the distinction; it is not a recommended debounce setting or evidence that every short pulse may be discarded.

Connect timing to the intended operation

Prepare fields for raw transition times, settled state, acceptance rule and accepted operations. Record both opening and closing if they matter to the application.

Ask which legitimate minimum event duration the actual system must preserve and which evidence characterizes the real contact. This worksheet helps review debounce behavior without hiding the response delay or treating a filtered count as a complete description of the physical contact waveform.

Customer Questions

Primary References

These references support the technical principles discussed in this guide. The worked examples and review questions are educational.

• Primary reference: switch bounce