The problem that you are experiencing may very well be due to the manner in which you are supplying your enlarger. The devices that are sold at computer stores are suspect in my opinion, they are more directed to controlling voltage spikes which are the other side of the equation from what you are experiencing. I have an Omega voltage stabilizer that I used on my old Omega D2 with an Aristo cold light source and I would be hard put to suggest that it's use would solve your problem. The things that I would do, if I were you, would be to try and solve this problem as simply and inexpensively as possible. The first thing that I would do is supply your enlarger with a source from your house (I assume) that has as few outlets on the circuit as possible. Certainly not a circuit that has a refrigerator, freezer, or furnace on the circuit. The second thing that I would do is to be assured that my extension cord be a minimum of 12 awg conducter. The third thing if that does not alleviate your problem would be to have an electrician wire a dedicated outlet fed from the breaker mains. But be sure that you don't indicate to him what you are using it for (he doesn't need to know) other then that you need a 20 amp breaker on the circuit. The reason that I mention this is that what you are doing is not in keeping with the universal electrical code. I have spent the last 30 years involved with this sort of thing. All by way of information.

Regards,
Donald Miller