[Arran]

Mike;
I used to use a dim bulb setup, before I had a Variac, I always regarded them as a poor man's substitute. and I don't think that I have used one since I acquired a proper unit. The best thing I can say is that they offer a "cushion" should the device being powered up develop a dead short. The way I used to use them was to start off with a lower Wattage bulb, and work my way up to a higher Wattage one in stages, like I said a "poor man's Variac". I have heard mentioned though that if the intent is to reform the filter caps it would be beneficial to construct a solid state substitute for the rectifier tube, as the set often has to be cranked up to 60-70 volts or so before the tube rectifier starts to conduct, I'm not sure how much difference this would make, and since I usually replace the filter caps as the first order of business I haven't had much reason to worry about it.
Regards
Arran