The microswitch is one of those components you see everywhere once you start paying attention. In your computer mouse buttons, in your microwave door, in 3D printers as limit switches, and in industrial machines as position sensors. Compact, reliable, and mechanically precise.
What is a microswitch?
A microswitch is a small mechanical switch with a snap-action mechanism: it switches at a predetermined actuation force in one rapid movement, regardless of how fast or slow the actuator is pressed. This results in virtually no contact bounce and a precise, repeatable switching position.
Three terminals, two states
| Terminal | Behavior | Application |
|---|---|---|
| COM (common) | Common | Always connect |
| NO (normally open) | Open, closes upon actuation | Signal when position is reached |
| NC (normally closed) | Closed, opens upon actuation | Safety circuits, limit switches |
For a limit switch in a 3D printer, the NC terminal is often preferred: faulty wiring or a loose connector will be detected immediately.
The Honeywell V15T22
The V15T22 from Honeywell is a microswitch from the MICRO SWITCH V15 series — one of the most widely used series in both industrial and hobbyist applications.
| Parameter | Value |
|---|---|
| Maximum current | 15 A at 250 V AC |
| Lifespan (mechanical) | Minimum 10 million switching cycles |
| Actuator | Roller lever |
| Application | Position sensor, limit switch, interlock |
The roller lever makes the V15T22 ideally suited as a position sensor in moving systems. The roller reduces friction and wear during repeated contact.
Typical applications
- Limit switches in CNC machines and 3D printers — detects the extreme position of an axis and halts movement.
- Door monitoring and enclosure detection — is a housing opened? Immediate signal.
- Safety switches — mechanical interlock when a lid is open.
- User interaction — buttons and levers where tactile feedback is critical.
Mounting: what to look out for?
- Actuation force and operating point. Check the datasheet to ensure your mechanical design provides sufficient force and travel.
- Protection. The standard version of the V15T22 is not splash-proof. Use an enclosure in damp or dusty environments.
- Wiring. Ensure proper mechanical strain relief of the wires to withstand vibrations.
