Variacs and possible alternatives

[Findm-Keepm]

Originally Posted by danrulz98

I was just thinking about this last night, variacs seem to be really expensive.
Just thought I'd compile my thoughts, maybe helpful for someone.

So, where would be a good place to find a cheap one.

I found one on ebay that I might just get,

Well, why not just use a straight dimmer switch?
I guess the simple answer to this is it just isn't the same. It uses a variable resistor instead of an autotransformer. It also wouldn't be able to handle a lot of amperage.
But, I really don't know on that one.

The one you see on eBay is fairly lightweight, good enough for radios and most TVs, but I'd recommend a higher amperage (actually a higher VA rating) for everyday use.

PM me - I have a hefty powerstat (~10 Amps, IIRC) that's yours for shipping (USPS parcel or Priority Large F/rate) - it's still in the metal box someone mounted it in at NASA Langley years ago.

I use a 22 Ampere Powerstat I got from NASA, fused at 7.5A for power on testing, and I can change the fuses to fit my needed safety margin. Massive monster for sure!

Cheers,

[Findm-Keepm]

The one I'm offering is a 116BU, same as this eBay item: 150258319426

PM me and it's yours for shipping.

Cheers,

[danrulz98]

Originally Posted by bandersen

I second everything Reece said

I use a vintage RCA ISO-TAP WP-25A isolation transformer and a modern variac from Circuit Specialists.

That seems like a nice cheap one.

What does the isolation transformer do? I know I've seen them and I have an idea as to what they do, but I've never been too sure.

Originally Posted by Findm-Keepm

The one I'm offering is a 116BU, same as this eBay item: 150258319426

PM me and it's yours for shipping.

Cheers,

PM sent.

[bandersen]

Originally Posted by danrulz98

That seems like a nice cheap one.

What does the isolation transformer do? I know I've seen them and I have an idea as to what they do, but I've never been too sure.

Some TVs and radios (AA5) ran right off the AC input without a transformer. Sometimes they would solder one side right to the chassis! Depending on which way you plugged in the non-polarized plug, the whole chassis could become hot An isolation transformer will make the set act as if it had a power transformer.

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