To stop your Spectrum's power socket coming unstuck, Stuart Cooke explains how you can make a simple power on/off switch for less than £3

A major omission from the Sinclair Spectrum is a reset or power off switch. The only way to wipe out an existing program is to pull out the power connector from the rear of the machine.

Unfortunately, the socket can become so loose from the wear and tear that the plug no longer fits tightly and the computer turns itself on and off at the most inconvenient moments, especially if you have caught the power lead.

This simple project should prevent many of these problems as it provides your Spectrum with an on/off switch and a power indicator.

Construction is extremely straightforward. First decide how you are going to place the components inside the box and then drill the holes where necessary. Next, lay out the components as they will fit inside the case and cut the lengths of wire necessary for them to connect inside.

It is probably a good idea to make the wires slightly longer than necessary as this makes it easier to manoeuvre the components once in the case.

The wires should be connected as shown in the diagram. Be careful to get the wires the correct way round, as an incorrect connection could damage your computer.

Connect the resistor to the socket. Use a bit of the sleeving from the cable to cover the legs of the resistor so it won't touch any component it shouldn't. The LED should be the last component to be connected as it is the one most likely to be damaged. Make sure you get it the right way round. The leg nearest the side with the flat should be connected to the resistor. Again, cover the leads with sleeving before joining it to the cable and resistor.

It's a good idea to check the wiring a couple of times before you install the components in the box.

When using the project the Spectrum power supply goes into the socket on the box and the flying lead from the box goes into the Spectrum. Now, when you want to turn off the Spectrum you simply press the button on the box. Don't forget that the power supply is still connected to the mains and should be unplugged when you're not using the Spectrum.

All components needed for this project are available from Maplin Electronic Suppliers, 0702-552911