DIY Simple Variac

DIY Simple Variac

I wanted to make a  power guard system for a mains voltage operated equipment. power guard increases efficiency and acts as an insurance against power fluctuation that could damage electrical appliances and electronic devices.in our country its possible to receive high voltages above 220v in mains supply line. some times it goes below the 200v so the equipment plunged in to wall sockets get damaged. as a solution of course there's lot of products available in the market to purchase but i wanted to make a DIY one. to do this you have to have a variac transformer for get low and high voltages between 100v and 300v. variac is a expensive unit. so i thought  of a way, get a transformer winded 220v to 400v AC then add a 220v ac dimmer to the transformer's input side.this way i can control the out put of the transformer.

ac out put of the transformer : 

 i have also added a dc out put channel to get dc volts :

output of the transformer with a load connected :

this project has come to an end with success.it took me long time to think of this simple way to accomplished what i wanted.

in action : https://www.youtube.com/watch?v=ns2auirpFP8