Making a 30W feedback transformer switching power supply circuit based on KA7805 chip

KA7805: There are four independent voltage comparators inside the integrated block. The characteristics of this voltage comparator are: (1) small offset voltage, typical value is 2mV; (2) wide power supply voltage range, single power supply is 2-36V, The dual power supply voltage is ±1V-±18V; (3) The internal resistance limit for the comparison signal source is relatively wide; (4) The common mode range is large, and the differential input voltage range is large enough to be equal to the power supply voltage ; (6) ) The output potential can be selected flexibly and conveniently.