No controller yet, just straight 12v. Thought it might have to be turned on and off manually but it was b***** cold out there tonight and I just left it on for the whole 2 hours.. Worked great, didn't get too hot and not a trace of dew on the objective
I'll have to make another one for the 102mm, still got 2/3 of the jug heater left.
There's probably controller kits available from other suppliers, but failing that theres circuits on the web to build from scratch.
Bill