I just bought a Gralab 900 digital timer and have the PDF instructions, but its not clear if I can tie the two outlets such that the safelight will automatically turn off when the enlarger turns on. Does anyone know if that is possible?
I am not sure what you mean by ". . . tie the two outlets such . . ." But looking at images of the back of this timer I think A will be for your enlarger and B for the safe light. You can simply try this out by connecting the enlarger and a safe light (or any light for that matter) into these two main sockets. When you switch on the timer the safelight will light up. Then, when you switch on the enlarger, the safe light will go off. If it does not work like that, switch the plug around . . .
Normally, with each socket, the info is written there: enlarger for one socket and safe light for the other . . . Fantastic system !