iam using forward converter two transistor as welding machine and i used timer 555 to change duty cycle from 0 to 0.5 and i need the circuit that between o/p pin of timer and the transistor and i have pulse transformer if anyon can help me
thanx

 

Why don't you post both what the original circuit was, and what your proposed modifications are?

.PNG is the best format to use, as .jpg images are "lossy" (fuzzy), .BMP images are large and many browsers can't read them directly.

If the duty cycle is zero, then there will be no output at all.