I am using the given schematic for voltage regulation using TL494. When feedback is not given, that is point A and B are not connected, then I am getting a pulse of 35% duty cycle of 0-12V. But when the feedback is given ( A and B gets connected), then in the output I am getting a 12V DC rather than a pulse even though the positive and negative terminal of error amplifiers have some difference of voltage and there's a sudden large amount of current flow at point C and D that is the primary side of the transformer. I am not unable to understand why the pulse is getting vanished with 12V dc and sudden large increase in current( i. e from 0.5 A to 1.6 A) in the primary side of the transformer circuit . Is there any blunder in the schematic.