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- chinsta00
September 4, 2006, 7:39 am

Is there such thing as a switchmode variac and where can I get one?
A google search seems to only turn up links to testing switchmode power
supplies by using a variac on the input.
Failing that, I suppose you could cannabilise the sinewave output stage
of a 12-240 inverter and bung it on the end of a variable high voltage
DC supply?

Re: Is there such thing as a switchmode variac?
snipped-for-privacy@hotmail.com wrote in news:1157355573.625800.244310
@m73g2000cwd.googlegroups.com:

There are supplies that can do that designed for EMC mains fluctuations/
flicker etc. They can simulate brownouts and are programmable. They would
probably work like a variac but they probably only go to 20-30 amps. They
will cost $5000 or more. (one brand I've seen is "Best") A 30 amp variac is
probably about 1/0th that price. What exactly do you want to achieve?

Re: Is there such thing as a switchmode variac?

I wanted to be able to control a variac by a PC/uC. I was guessing
that an interface to the switchmode variac would be as simple as a low
voltage control input in the feedback loop somewhere.
The other low-tech option I was thinking of was a motor (with
positional feedback) driving the variac knob.

Re: Is there such thing as a switchmode variac?

or a 50Hz oscillator - feeding a digital volume control chip - feeding a
power amp (an AM1600 will give 110V RMS or so out ) maybe feeding a
Transformer (better watch the DC offset of the amp then - I dont think an
AM1600 would work here ...) depending on what Voltage range you want ....
Bit complex isnt it ? the Motor feeding a Variac would be cheaper/easier
....
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