I have finally completed my Durst Laborator g139 that was missing many parts. I will be using a 500w bulb that I want to use at no more than 300W. For this I just purchased a Variac, or Variable auto transformer. Now the challenge for me is to find out the configuration, the "sequence", on how to connect the enlarger, Variac and Gra Lab timer together. Is it even possible? Thank you.