How to relay a progressive controller

Cool. Let the experiments begin! No, wait, I've got two other electronic projects to deal with first, now I'm getting all this fantastic support, thank you everyone. It's very much appreciated.

If I may revive this thread as I think I've found another alternative in the form of a solid state relay apart from one aspect. The specs are as follows;

Control - 3-32VDC
Load - 24-220VDC @ 40A

Ok, for my application the control will be -12VDC but the load will also be just 12VDC, not 24VDC which appears to be the specified minimum requirement. Is that going to cause incompatibility? It seems to work ok with a 12v LED as the load but without a 'scope (which I don't own or know how to use properly), I can't be sure it's perfectly relaying the control signal? All advise gratefully received.

I can answer my own question - it seems to work just fine so I don't understand why the load rating is 24v and up.