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How to Use a Microswitch for Powering On & Off

A microswitch is used for electrical applications that require small movements to open and close a circuit, such as model railroading and designing a computer mouse or joystick. A microswitch can be wired to power your circuit on, when the handle is pressed, and off, when released. This sequence can also be reversed to power a device when the handle is released. Install a microswitch at your model railroad turnouts, to switch tracks rapidly.

Things You'll Need

Alligator clip wires
Clamp
Small light bulb
Battery

Instructions

- 1
  Determine the location of the three microswitch terminals. One terminal should be labeled with a letter C, for "Common." The second terminal should be labeled with the letters NO, for "Normally Open to Common." The remaining terminal should be labeled with the letters NC, for "Normally Closed to Common."
- 2
  Connect an alligator clip wire between the C terminal on the microswitch and the negative terminal on a battery. Connect an alligator clip wire from the NO terminal to the thread side of a light bulb, or the positive end of another type of resistive element. Connect the bottom, or negative, terminal of the light bulb to the positive terminal on the battery, using an alligator clip wire. Clamp the clips to the top and bottom battery terminals.
- 3
  Press the microswitch lever to power on the light bulb. Release the switch to power off the light bulb.

Model Railroads