Hello Roy
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
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-----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