Hi guys,

As I'm very shortly going to be unemployed (contracts up and UK market is down) it's time to play around the house with some toys.

I recently bought a new heating/hot water controller for the central heating, and frankly it's rubbish. It only allows 3 'ons' and 'offs' for each system, and I have no thermostats in the house.

If I'm going to run wires around my building, I want to connect the heating controls to my PC so I can have it switching on and off. However PC's are a little prone to crashing, so I want to connect up one of my 8052 boards to the heating system, which will have to switch mains voltage.

I know the following :-

1) Be *very* careful when playing with mains power

2) it's 240VAC

3) I need a relay transistor and a diode to actually switch the power.

I've seen a few schematics around the web, but I'm not sure if they are suitable for 240VAC as most sites are American and they use 110VAC

Does anyone know of a schematic for switching UK mains voltages.

Also does anyone know how long an RS232 cable can be? I think it's about 40ft from the computer to the central heating system.


Chris (will work for food) Brooks.