24v Limit/Home switches. How to..?

[Wal]

Any particular reason why you bought the 3 wire NPN switches instead of the 2-wire ones?

Birchy - Errm. Yep. A thorough lack of understanding would probably be the main one... I'm right in thinking that a 3 wired switch can be used NC and NO and the only detrimental effect in my application is it being a bit untidy..?

Irving - Sorry mate, you're speaking to an electronics Dunce - I sat there looking at those circuit diagrams and all that happened is that I began to sweat... There's zilcho documentation with my BOB so I'm not entirely sure which of the diagrams applies to me. I know that it (my BOB) does feature optocouplers, but have read that they're best ignored (very slow apparently). Dunno where that leaves me. Let's say I do eventually find BOB documentation - are you just using a resistor to limit the voltage going into the BOB.

Any chance of a layman's explanation of the theory of how this is achieved..?

Wal.

Yes, I know I should have payed more attention in physics.