I have a Gralab 450 timer, it works very well with all my enlargers and heads
except with my Aristo VCL 4500. The VCL has a power relay too, and it needs very little
energy to switch the lamp on...it seems to little energy for my Gralab timer.
The Gralab lets the time run off, jumps to the starting point and lets time run off again,
and again...and again...
I noticed, that if i put a second electrical part to the power outlet from the Gralab,
so that more energy must be switched, it works without any problems.