What Is a Micro Switch / Limit Switch?
A micro switch (snap-action) is a precise switch that changes its contacts suddenly with a very small movement and force. A limit switch, a lever/roller version of it, senses the limit of moving parts.
Snap Contact
The spring mechanism inside it suddenly opens and closes the contact when the threshold force is reached. This lets the contact switch quickly "without hanging" even on a slow press; arcing and instability are reduced.
Three-Terminal Structure
A typical micro switch has three terminals: COM (common), NO (normally open) and NC (normally closed). So both press-to-conduct and press-to-break connections are available in one switch.
| Terminal | Function |
|---|---|
| COM | Common supply |
| NO | Conducts when pressed |
| NC | Breaks when pressed |
Where Is It Used?
Printer/3D-printer axis limits, door/lid detection, elevator safety, home appliances and machine position limiting. It reliably reports that the position is "exactly here".
Limit Switch Actuators
Limit switches come with actuators such as a lever, roller or rod; these tips soften the contact of the moving part with the switch and adapt to different geometries.
Common Mistakes
- Excessive force: forcing the switch's travel limit breaks the mechanism.
- Mixing NO/NC: the safety logic is built backwards.
- Debounce: bounce must be filtered in precise position reading.
Frequently Asked Questions
What's the difference between a micro switch and a limit switch?+
Why "snap" contact?+
Search parts related to "What Is a Micro Switch / Limit Switch?"
Find the right part by comparing price, stock and distributors.