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How to Wire a Microswitch

Use a microswitch in various hobby projects, such as model railroading, robotics and joystick control. The microswitch enables the state of an electrical circuit to be changed rapidly with minimal applied force. Invented by Peter McGall in 1932, the microswitch is a favorite of model railroad hobbyists for automatic track switching and lighting effects.

Things You'll Need

Alligator clip wires
Small lightbulb
Battery

Instructions

- 1
  Examine the electrical contacts on the switch. The common terminal may be indicated with the letter C. The normally open to common terminal may be indicated with NO, and the normally closed to common terminal may be indicated with NC.
- 2
  Wire the switch to complete a circuit when pressed. Connect a wire from the C terminal to the negative terminal of a battery or electrical source. Connect the NO terminal to the load or resistive element, such as the thread-side of a lightbulb. Connect the bottom of the lightbulb to the positive terminal of the battery. When pressed, the bulb will light.
- 3
  Wire the switch to open a circuit when pressed. Connect a wire from C terminal to the negative battery terminal. Connect the NC terminal to the thread-side of the bulb, and connect the bulb end to the positive battery terminal. When pressed, the bulb will turn off. Conversely, when left unpressed, the bulb will remain lit.

Model Railroads