Now I am going to ask 3 stupid questions, please dont laugh. but i cant seem to find info

[Brad Hruska]

Analog Kid,
Thank you for a crystal clear as a diamond, explanation. This is exactly what I was trying to understand. I love your clarity it is so refreshing! You get another like, wish I could give you 10 but the system wont let me.

Ps Remember that base station you helped me with? It is finally finished and up and running. Thanks with the alarm circuit!!

Because a Variac basically is a tapped inductor, its current rating is limited by the wire gauge. Winging some numbers here - let's say it is wound with #22 wire and rated for 120 V, 1 A. When you turn the tap down to the 10% point (12 V), you cannot pull 10 A out of there because that 10 A has to pass through the other 90% of the winding, and that still is only #22 wire.
ak

 

[(*steve*)]

As an interesting aside, I have an autotransformer that is designed to step down 250V to a variety of lower voltages between about 200V and 230V at 20A

Part of the winding is very heavy wire, and the rest is much finer. Because it's not a variable autotransformer, only part of the winding needs to be able to handle the maximum current.

It's heavy enough that I wouldn't want to drop it on my toe, but light enough that a steel cap boot would probably protect me.

 

[AnalogKid]

Ps Remember that base station you helped me with? It is finally finished and up and running. Thanks with the alarm circuit!!

I remember the circuit, but I don't see any postings of mine in the thread. Did you post the same project on another forum?

ak