I think the Duty cycle of the timer chip needs to be higher and you can't use a 2n3055 a IRFP450/60 will do the job. Look at this site it will explain how the circuit works. (Don't copy the circuit off that site you will get a voltage way higher than what you need, reduced duty cycle on the sites circuit would fix that problem). Other than that the TC circuit looks fine. (Maybe I wouldn't ground the TC to my circuit).