I do have a variac, but I have no idea how to use it.. it came with my current psu, I paid 20 bucks for both at a yardsale a few weeks ago..Transformers are pretty rugged devices, put a fuse in any line when testing.
The low voltage are usually put on last, tube filament for a tube amp were often 5v and 6.3v
A variac is usually the best way to test if you have one.
Max.
Think of a Variac as a transformer with a variable turn secondary.I do have a variac, but I have no idea how to use it.. it came with my current psu, .
its every bit of 6 pounds, 3.5 inches tall and 4 inches wide. its a pretty stout transformer. its a Marantz power transformer, I ran the numbers on it and it went to a Marantz home audio tube amplifier so It should be able to do a fair amount of current..The tougher question is how much current can your transformer supply. A 4 amp one at 40 volts will probably weigh 6 pounds unless it's a toroid.
makes sense,, I wondered what the big knob on top was for. Its big,green and has all kind of numbers on it.. could I use that to drive a tesla coil? I seen a video of a 4 foot tall one and it had one of those connected to it..Think of a Variac as a transformer with a variable turn secondary.
IOW the turns ratio, and hence output changes with a rotation of the knob.
It is however a auto-transformer, so there is no isolation between supply and output.
Max.