I designed a fly-back circuit with TNY280 and I got wrong answers. I actually want 14.5 volt and 1 A in the out put but I after a while (about three seconds) the voltage drops down and it will goes up again. The other problems is that the output voltage varies with the load. Fore example, if I use 18 ohm as the out put load I get 14.5 volt in the out put and also have the above problem, but If I use 33 ohm in the out put I get 22 volt in the output and also face with the above problem, as well. I should notice that: as I rise the out put ohm, the out put voltage drops down sooner.
The schematic, further information and picture of the circuit is attached to this massage.