Electronics > Beginners

Where to buy an isolation transformer ?

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lordvader88:
I want to be able to a scope and repair household electronics, so I guess 500W should cover most things.

But where to get 1 ? Searching 'isolation transformer' and my hometown doesn't come up with much at all. There's not many electrical supplies places here, I can start phoning around to places.

There's not really anywhere with used industrial machinery for sale that I could salvage a transformer from.

On ebay Canada they are +100 for 300W, $180 for the 1st 500W

Kjelt:
You know any ham radio clubs in the vicinity or old crt repair shops that went out of business, there you can pick them up sometimes in a variac version almost for free. Shipping is usual the costs, those things are heavy.

RoGeorge:
Beware of the variacs, many of them are autotransformers, so the output is not galvanically isolated.

At 500W, it can rather make sense to use a handheld oscilloscope, or to float the oscilloscope instead of floating the DUT (Device Under Test).

I made an improvised DYI isolation transformer out of two identical 220V/2x22V (they were meant for a stereo audio amplifier with independent power source for each channel) connected secondary to secondary, and the remaining primary windings were used as isolated input/output.

220V/2x22V -> 2x22V/220V

Since each transformer has symmetric 22V secondary winding, I can also connect the 22V secondary from the first transformer to the 44V of the second transformer, so in the end I can get an isolated 220V/110V, too.

lordvader88:
I have a 2000W auto-transformer

I just phoned around and most suppliers don't have them at all or deal with anything as low voltage as 120V or 240V. The only price I got was +$200 for a 120/240:120/240 500W unit

ebclr:
Pick 2 microwave old transformers, and make yourself, Just Cut the 2 high voltage coils, and maintain the  2 primary coils on the same core, Will work like a charm

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