Making Switches

switch on

Now you know how to make a basic circuit, this tutorial will teach you how to add a switch to your circuit so you can turn the LED on and off.

Components:

Tools and other materials:

  • small binder clips
  • pen or pencil
  • clear tape
  • card stock paper
  • scissors
  • xacto knife and cutting mat (optional)
  • tweezers (optional)
  • soldering iron and solder (optional)

What is a switch?
A circuit with a switch is basically a circuit with a gap, such that when the gap closed, the circuit is complete. The switch is the part of the circuit that completes the gap. In this circuit, closing the switch completes the loop in the circuit, allowing current to flow from the battery to the LED. Thus, when the switch is closed, the LED will turn on.

switch off diagram switch on diagram

To create a circuit with a switch, leave a gap in the circuit at the lower right corner of the page. This breaks the loop in your circuit so the LED will not turn on unless you close the loop by turning on the switch.

switch circuit
On the lower right corner of the page, tape a piece of copper tape so that it completes the gap when the corner of the page is folded up. The fold at the bottom of the page acts as the switch and the LED light will turn on when the corner is folded. Make sure that the piece of tape in the corner touches both ends of the circuit when the corner is folded over.

add battery to switch circuit
To turn on the LED, add a battery to your circuit and secure it with a clip.

switch circuit on
Then, fold the corner to turn on the switch.

Here is a video of how the switch works:


Variation: Blinking LED

blinking switch circuit
To create a circuit with a blinking LED, create a gap in the circuit with parallel ends. Rip the page a little bit at the seams of the notebook from the bottom of the page until the top dotted line. To make the switch, tape some vertical pieces so that when the page is folded up at the dotted line, the vertical pieces will fill the gap between the two parallel pieces of copper tape.

folding up switch
To make the LED blink, fold the bottom of the page up and move your finger horizontally along the switch.

blinking switch circuit on
The light should turn on whenever your finger is above one of the vertical pieces of copper tape. This vertical pieces of tape completes the circuit and allow the LED to turn on. When you run your finger across the switch, you turn on and off each switch as you touch the copper tape beneath the paper, creating a blinking LED effect.

Tips:

  • Make sure the pieces of copper tape are spread out far enough so that when one piece of tape is pushed down, it does not affect the adjacent piece.

Here is a video of how the blinking switch works:

Example projects:
alarm clock

baking

>> Chapter 4: Using Sensors