This I did not know about variacs...

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dtief
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Re: This I did not know about variacs...

Post by dtief » Sat Mar 07, 2009 5:35 pm

Measure ing the resistance regarding the turns "shorted" by the brush isn't the whole story. This is a transformer, not a resistor / potentiometer. The turn/s shorted by the brush will have the ratio of the number of turns from the 2 terminals used for power input to 1. The brushes are low ohms, but not zero. The losses from the shorted turn and the output current rating would be figured into the design of the brush.

To estimate what the losses are, it would be more useful to measure the voltage across 1 turn, and the resistance of the brush.

Or measure the supply current with no load, and slowly make adjustments in the position of the control knob. Then put the tape under the brush to compare to "ideal".

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CeaSaR
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Re: This I did not know about variacs...

Post by CeaSaR » Wed Mar 25, 2009 6:03 am

CeaSaR wrote:I'll upload some pictures later.
Okay, here they are:

Image

Image

Image

Image

I have no idea what it was used for. When I found it, most of the buildings were
demolished. This was found near one of the remaining foundations, possibly the
kitchen or...? I do know that the place had wires strung between the trees with
light fixtures attached along the way, so that the kids at the camp could see in
the dark. Could have been in the pool area also. I'll probably never know.

CeaSaR
Hey, what do I know?

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dtief
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Re: This I did not know about variacs...

Post by dtief » Wed Mar 25, 2009 5:30 pm

That looks exactly like the pair of 120V 2KVA theater dimmer variacs (actually Powerstat brand) I have. Mine don't have boost taps like "electronics" variacs often have.

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