I've made a 150w flyback circuit but it never worked and i can't figure out what is the mistake i have done
i have attached the schematic here most of it i got from the internet with some tweaks I've! done on it i added some resistors in parallel or series to get certain values since i was building this circuit completely from my junkbox
input = 220v 50hz output(should be) = 30v 5amp frequency = around 80khz
transformer is an EI40 core with an airgap of 0.33m the primary side is 15turns in 2 halfs first one is 8 turns then the secondery side is 6 turns , aux is 3 turns , then finally the last 7 turns of primary (the dot here means the beginning of the winding and the output side dot is reveresed but that's the closest library i could find)
IC2 IS A TL431
Schematic
first test run output was zero
i started checking out components i found the mosfet dead all leads are shorted
also the auxulary winding diode mur160 was shorted
having a closer look i found the UC3842 pin 7 and 8 traces joined togther by a tiny copper and i cleared that
replaced the mosfet diode and UC3842 to be safe made another test and nope still no output this time the mosfet didn't die i can see 12V at the 3842 vcc which didn't appear before and pin 8 output is a few hundred mili volts
i suspect the MUR160 diodes are too slow for this circuit is that correct ? what else should i look for ? i can't really figure out what is wrong or why is it not outputting anything
It worked! , i changed the UC3842 with a 3843 IC and it worked perfectly , i think the aux winding was not supplying enough voltage to start the 3842 but the 3843 works on a lower voltage.
