Good Variac for DIY use ?

[vonfilm]

Would this be a good inexpensive Variac for DIY use?

http://webtronics.stores.yahoo.net/ensavat.html


Any other suggestions?

[Mooly]

Sounds very cheap to me. Remember a Variac provides no isolation. Don't use a variac on SMPS's , a lot will not start correctly and may self destruct.
Alternatives, 100 watt bulb ?

[Conrad Hoffman]

That's exactly what most people would want for their test bench, and the price seems very good. Too good? Remember that Variac was a trade name owned by General Radio Corp. (GenRad), though I don't know who owns it now, the unit shown is likely not a real "Variac". Powerstat is one other well known name.

They're all autotransformers with no isolation, so the caution above is something you should pay heed to. I power amps and things that have their own isolation transformer from my Variac at the bench. For SMPSs I have another plate that carries a Variac and a big isolation transformer. This serves a dual purpose. It gives me isolation for things that need it, plus I can switch the wires on the isolation transformer to get 120 or 240 VAC, as needed.

Note that the typical wiring for a Variac will allow a slight overvoltage, usually 130 VAC or a bit more, so don't just crank it up without checking the output.

[vonfilm]

I am not sure what is meant by "isolation" My initial use would be to slowly power up a Chipamp.com 1875 Power Supply and amp which has its own toroidal transformer.

[Mooly]

It means the output is still 100% connected to the mains, not isolated like a transformer would be.
You don't need buy one just for running a chip amp up use a low wattage bulb in series with the mains -- perfect.

[Apex Jr]

Vonfilm...
The link you posted are for the cheap China made variacs
they will not last... Like above mentioned if you really
feel you want a REAL variac there are only 3 name
brands:

General Radio, GenRad and Technipower (All the Same)
Superior Electric which is the name Powerstat
Staco

Steve @ Apex Jr.

[lineup]

Steve
you forgot the Tufvassons
http://www.tufvassons.se/eng_start.asp

http://www.tufvassons.se/vridtransformatorer.asp
They are supplied in Europe by www.elfa.se

[vonfilm]

Who is a good USA source for a quality Variac?

[Apex Jr]

To Lineup...
I have never heard of Tufvassons, and went to there website
and all they stock is 230V input and not good here in the
states..The ones I mentioned make the 230V versions too..
Pictures look fine but I suspect Vonfilm would want enclosed
type rather than building an enclosure.


To Vonfilm
I have some reconditioned units in stock. from the
manufacturers I mentioned above and can contact
me thru email at steve.apexjr@prodigy.net
for what your looking for and we can talk from there.

Steve @ Apex Jr.

[Conrad Hoffman]

You know, an autotransformer doesn't have a fixed ratio, and it usually adjusts from 0 to 130%. That means that the voltage rating isn't terribly important. I think a 230VAC unit would work just fine at 120VAC, even better if it was designed for 50Hz- the better steel would be lower loss at 60Hz.