Micro Switch

Part images

What it is

A micro switch is a small snap-action switch with an actuator that changes contact state when pressed by an object.

How students use it

Students use it as a limit switch, bump sensor, service bell, door sensor, or mechanical checkpoint in moving projects.

Pins and power

Common, normally open, and normally closed terminals. SunFounder labels the terminal roles in the internal diagram.

Passive switch. Read it with 3.3V-safe digital input wiring and a pull-up or pull-down path.

At rest, normally closed is connected to common and normally open is open. When the plunger is depressed, normally open connects and normally closed opens.

Voltage and safety

Use it only as a low-voltage input in ObsoleteHQ projects. Do not use its contact ratings as permission to switch unsafe loads.

Mount moving parts so they press the actuator without crushing it. Power off before changing switch wiring.

Module internals

Plunger, cover, moving piece, support, case, normally open terminal, normally closed terminal, contact, and moving arm.

Datasheet notes

SunFounder explains the mechanism and terminal roles but does not identify a manufacturer part number. Match the exact body markings before using a rating from a datasheet.

Common libraries

No special library is needed. Use machine.Pin and debounce the reading in software or lesson logic.

Common mistakes

Mixing up NO and NC, forgetting the common terminal, letting the input float, and ignoring contact bounce.