Q3 getting hot

[gold1958]

Can anybody help with this problem. The flyback voltage seems to be correct about 300v but Q3 (IRF 740) gets very hot. The circuit is drawing about 2 amps while the coil is connected. If I vary the frequency or the pulse width there is a small change in the current draw. F=1250hz pulse width 25uS, the coils is 250mm and 26 turns of 0.4mm wire.Thanks Saul

[Carl-NC]

How hot? Too hot to touch? Mine only gets hot at high frequency & high pulse width, warm otherwise.

[gold1958]

Found the problem

Hi Carl thanks for the prompt reply I found the fault, I did not short out R 7 and R 8 which caused Q3 to get extremely hot. I must thank you for a great project and a really good forum.
Thanks Saul -- Cape Town