Adapting battery operated toys for use with switch use

Commercially available switch adaptor leads that fit between a battery and its contact have proved invaluable for giving switch users control over simple on/off battery operated toys. When the toy is designed to move, however, these leads can prove to be less reliable, and sometimes fall out completely. This article describes how to effect a more permanent solution using a few simple tools and cheap, readily available components.

Tools you will need

You will need: 

• Screwdriver (for removing the base of the toy)
• Wire cutters/strippers
• A soldering iron and solder. If you haven't used a soldering iron before, don't worry - it will only take a few minutes to pick up the technique. Try practising on a few spare pieces of wire first. You can buy cheap soldering irons from hardware or similar shops, and most will have instructions on how to solder effectively.
• Sharp craft knife

Components

• A 3.5mm mono in-line or cable mounting jack socket (available from electrical component or audio shops)
• A length of low power twin-core speaker cable or bell cable (available from hardware or similar shops). For more mobile toys, multicore cable may be a more durable option. The length of cable required depends on the action of the device you are adapting. If it is a fairly static toy or device, a short length (enough to reach from the battery terminal to outside the toy) will be sufficient. You may wish to use a longer length for a toy that moves a distance, so as not to restrict its movement.

What to do

1) Unscrew the plastic cover of the socket and thread one end of your cable (coloured green in the diagram below) through it.

2) Strip off a small amount of insulation from each of the two cores at one end of your cable and twist the bare wire strands between your fingers to prevent fraying. Solder each twisted core to a prong at the base of the socket. Screw the plastic cover back on.

3) Remove the base of the toy so that the wires coming from the battery compartment (it is worth checking before you purchase a toy that it's not a sealed unit).

4) Find the wires that are attached to the battery terminals (coloured red in the diagram below). Work out how the cable is going to exit the casing of the toy before you solder – you may have to thread the cable through an existing opening or cut a hole or slot in the case with a craft knife)

5) Cut one of the battery terminal wires (it doesn't matter which one) and strip off a small amount of insulation from each cut end.

6) Strip off a small amount of insulation from each of the cores at the remaining end of your cable. Solder each core to a cut end of the toy's wire.

7) Insulate the bare wires where the solder joints are. (Heat shrink sleeving is best but insulation tape will do)

8) Replace the base of the device.

9) Switch the toy ON using it's own built-in switch. Nothing should happen. You have effectively broken the circuit and the toy is waiting for your external switch to be pressed to activate the device.

10) Plug your switch into the jack socket and give it a go! (you will have to maintain pressure on the switch to keep the device running)

Last updated: 06/11/07