Re: (OT) repair tools: Autotransformers/variacs
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Hello Roy
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Your experience with plug reversal brings up the importance of every Variac having an attached isolation transformer. I work on a lot of consumer electronics (lots of switching and transformer-less-power supplies) and the isolation saves a lot of scope probe ground leads not mention the scope user. Back in the ac/dc radio days I used a 100 watt light bulb in series with my suicide cord since I was so frugal and tubes were so much more forgiving of short term stress. With age comes wisdom if you are lucky. 73 Eric WB6KCN -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Roy Morgan Sent: Saturday, June 27, 2020 11:17 PM To: [email protected] Subject: Re: [TekScopes] (OT) repair tools: Autotransformers/variacs Hello Ernesto, I agree that most of us do not need the overvoltage. I did use it in final system testing of new equipment to ensure that it would operate properly at high line voltages. I think that all but very small variacs have screw terminals that make connecting for only line voltage maximum easy. And some dial plates can be reversed to indicate that. Briefly, the danger from fixed line cord plugs comes from the fact that an overload usually blows only one fuse, and the plug can be plugged in so as to put the equipment at full line voltage. Fused line cords I have seen are not polarized. I have not thought about suicide cords, but even if the plug is polarized, the clips on the other end can be connected to the equipment backwards. Tomorrow I can send you the diatribes. Roy Morgan K1LKY Western Mass |
Eric Schumacher