Can someone recommend a good Variac?

[johnnydiaz]

Im looking to purchase a Variac. Can someone recommend a good one? How does the link below look?

http://www.ebay.com/itm/AC-Output-Va...item25784e4b1e

Thanks,
Johnny

[tom66]

Re: Can someone recommend a good Variac?

A bargain for a 2000VA variac, but there's no way you'd ever need that for most power supplies. For example, a plasma TV at full brightness (all pixels white) might be 600VA for a very old model.

[johnnydiaz]

Re: Can someone recommend a good Variac?

I understand. Have you used this brand before? What should I be looking for when buying a variac?

[Toasty]

Re: Can someone recommend a good Variac?

Understand that a Variac (aka: autotransformer) is -NOT- an isolation transformer. You should be using an isolation transformer when working on live electronics, especially on SMPS as one side is HOT with respect to earth ground.

See: http://en.wikipedia.org/wiki/Autotransformer

You can use a Variac with an isolation transformer.

I use these isolation transformers in the shop: http://www.ebay.com/itm/121042522544

T

[budm]

Re: Can someone recommend a good Variac?

I myself use STACO, all the one we bought still work fine after 15 years (ther are used everyday in our test & repair and in our labs, no new brushes, no arcing. The one shown on EBAY, we bought a couples (similar, they all look the same) to try out, last about 6 months, the switch welded itself due high in-rush (Variac winding is on donut shape core is like a Toroid transformer, the 500VA has 150A inrush), the outlet no longer grab the plugs, brushes were arcing and the section of the winding (around 110~130V) just worn out.
The STACO is expensive but if you can find used one, that will be better than those cheaply made Chinese version. If you do not use it that much, then you may be able to use them.

[japlytic]

Re: Can someone recommend a good Variac?

In the Serviceman's Log of Silicon Chip magazine, I remember reading that an old Variac failed; it was caused by a failed wiper that travels along the transformer windings.
Something to look out for in older Variacs...