Originally Posted by rmay635703
Honestly a set voltage would be fine, but sadly I need to find what it is. (It's between 140-160 volts) the 220vac output variacs seem to be much larger and more expensive than I would prefer..
The 140 volt units seem to not go past 1:1 which makes them useless to me.
Being able to put in either 110vac or 220vac and get around 150 would be nice but not necessary.
Thus far there only seem to be 2 main styles of variac and the ones that boost aren't in those common categories.
You can use an isolated
AC source to add it's voltage to another AC source, as long as they're in phase with each other...
...meaning if you had a 120v to ~30V AC transformer, you could put it in series with the 120v from the outlet, and the two will add together to give you 150v AC. As per this informative article (which I would not recommend for complete novices to follow):
Battery Charger Schematic (Bad Boy)
You could also use an isolation transformer instead of straight-from-the-wall power to completely isolate it. Or combine a variac with an ~30v (isolated) transformer to give you the ability to alter the voltage.
Please note that a variac IS NOT ISOLATED...and trying to combine it in series with it's own source will end in the apocalypse...at least as far as you and anyone in the room with you is concerned anyway. Wasn't there something about not crossing the streams in ghost busters? Well, this won't have a happy ending...
Be safe! (and if you don't need this warning, well, some people out there reading probably do)
BTW, what are you trying to accomplish?