build your isolation transformer
 

here is a handy little thing iv done for yrs when i needed a transformer for a project or just playing around .instead finding a transformers with the ratio you need and spending to much when you find it,there are alot of old transformer's in things everyone throws away esp. microwave ovens even if the trans is burt up you can easily disassemble them. and remove the bad coil, because each coil is seperate and made individual you can take a number of different trans apart and assemble them the way you want. like i needed just a simple isolation trans small a compact , instead of draging around my bigger one i have on my bench. now remember all trans are not built in this way ,so its easyer to pick out this style .

now here is reasembled in its new configure , make sure to fill all gaps with the steel left over from other trans .

and those microwave capacitors pack ONE HELLLof a bite!!! :D
SR

finished after welding the core back together ,it now has two primary coils from two bad microwave trans put into one core ,each coil has a equel amount of turns and can be used as a isolation trans.

yeah they do ,but there not used in what i built i just wanted a one to one ratio trans.

after testing it out works great ,ill show picture later

Brilliant idea, and probably cost you nothing!

Those coils sure look different though....

Now THAT'S determination!

no cost , just two old transformer primarys the gauge of wire on one was alittle smaller than the other ,but resistance .5 each inductance real close useing a tuning eye on a cap meter . both old trans had secondary were overheaded ,but primarys in perfect shape. probley depending on the quility of transformer youll find cheap wond transformers with bare min. amount of windings and wire quility than others ,but you collect enough old power trans you can pick out size of cores and coils and make what you want .what was unuseble junk is working again .

most of the time between brands and quility on the trans ,it turns out perfect like this one 120v in output on other coil 112-117 v perfect for a isolation trans or reverse it to fit what you want a slight step up trans.ill show later today in pic how watts it is useing a fixed load i made with incondesent bulbs .

really it took under 1 hour and thats just picking and choosing the parts.

Here's one that I threw together about 30 years ago. I had a pair with the same
1:2 ratio, so in this case, inputs were tied together. The first trans would halve the voltage, and the second one would double it.

had a chance to test it out alittle today,at 122v input no load was around 117v output .i just pick witch coil i wanted to use for input and output by the best results since the coils being both from microwaves and both are primarys there are not act. the same transformers and act match's of coils but are close enough to fine i perfer a drop in voltage.

now i use light bulbs as a fixed load the bigger bulbs are 300 watt at max load of about 700watts the voltage drops to 104v output, but im not finished really it is hooked up to my variac and the input might have also dropped but you can get a good idea how well it works later when i have more time ill do a better test .

i also have done it that way ,but im to much of a packrat of parts i would want to save one of thoughs trans for another project .lol