School Science/Simple switches

A single switch is a simple device for showing single pole single throw (SPST) switches for use in school laboratories. A cost-effective way of making simple switch units to use with 4mm leads, follows.

See also: ../Cell holder

Equipment Required (to Make 30 Single Switches)

 * 30 pieces of wood at least 150mm x 40mm and 7mm thick
 * 60 pieces of 0.1mm copper foil (available from most Chemical suppliers) cut into 10mm x 70mm strips and 10mm x 25mm strips.
 * 4mm terminals, 60 black and 60 red (available from most electrical component retailers)
 * 120 drawing pins
 * Extra flexible lead wire, black and red
 * Solder + soldering iron
 * Pliers
 * Screwdriver
 * Drills 7.5mm & 5mm
 * Solder Flux
 * 60 pieces of wood for feet (optional)

Fig. 1 Simple Switch Diagram  Fig. 2 Simple Switch

Method for making the switches

 * 1) Get the wood cut the wood to the correct size and sanded if need be.
 * 2) Drill 2 x 7.5mm holes at either end as show in fig 1.
 * 3) Drill 2 x 5 mm holes near the larger holes as in fig 1.
 * 4) attach the larger piece of foil to the wood using the drawing pins, as shown in fig 1. Then bend it over slightly where the drawing pins are.
 * 5) attach the smaller piece of foil to the wood using the drawing pins. as shown in fig 1.
 * 6) Insert the 4mm terminals in the larger holes, one of each colour in either end, and secure with nut.
 * 7) Cut a 50mm piece of each wire, strip the ends and solder onto the 2 pieces of copper foil. as in fig 2. Ensure you have got red wire to the red terminal and black wire going to the black terminal. Then push the wire through the 5mm hole and out the other side so you can then solder it onto the 4mm terminal.
 * 8) It should look something like this. see fig 2. these are usually very durable and can be used in conjuction with cell holders and bulb holders etc.