Insulated vario trafo

I have found a need for a variable ac supply, for when i am experimenting on my bench. But I have also seen the need for an insulated power supply. Often is the isolation transformer placed just before the outtakes. I put it first to have both options, a fixed output, and a variable output.

On a Danish site equivalent to craigslist, I did find an old beaten down variac transformer, and an old insolation transformer, that I used for this project, in a new case. They are only rated for 2A, that is 460W, at 230V. That a linear power and means 1A at 115V and so on. And for now, I do not forecast the need for more power.

This has later been updated with a 0-390V DC, inspired by a video from Tony Albus. The maximum output voltage surprised me a bit 280V AC * √2 = 394.5V DC

The discharge resistance is important, it prevents you from getting a strong electric shock from the charged electrolyte capacitor. and must be able to handle some watts. Starting power across the resistor is 68W and the total energy discharged to zero volts is 17.2 J.

The protective earth wire is not wired through to the outlets as in normal TT-earthing systems witch is the normal in residential housing, with separate earth wire. Instead, I make an IT-earthing system, the I stand for "Isolated" and prevent faulty current, to return to the, making it able to travel through your body.

variac diagram
variac project case
variac project inside
© 2007, Seahawk.dk Cookie & Privacy policy