Can anyone give me a circuit ( preferably using relays ) that when power is applied would switch on 1 device.
Then when power is next applied would switch on device 2.
Then when power is next applied would switch on device 1 again.

hi, maybe i could help, could you tell me what youre trying to do?

Think a change over relay may be what you need Clive? One relay to power both circuits

For up to 2A this relay should do exactly the job you describe. It's a changeover latching relay, ideal for a push button control (don't try to drive the coil off a regular toggle/rocker switch because they don't like that).

http://www.maplin.co.uk/Module.aspx?ModuleNo=37529&C=SO&U=strat15

If you want more power it would be simple enough to get it to drive 2xregular automotive relays to switch up to 30-40A each.

[Edited on 26/6/09 by iank]

Ok, I didn't explain this very well so I will try again.

Turn on the switch and only circuit 1 is powered.
Turn off switch and circuit 1 turns off.
Turn on the switch again and this time only circuit 2 is powered.
Turn off the switch and circuit 2 turns off.

Basically every time the switch is turned on the opposite circuit is powered. eg 1 then 2 then 1 then 2 then 1 etc.

Hope this makes sense to somebody

I think what you need is a 2 bit relay binary counter.

Some light reading on relays circuits.

Linky

Just my brain has stop working lately and can not remember how to use relays for your function.

Next best option would be to use some simple logic gate circuits to drive 2 relays.

Martin