Well.. Got stuck in the Corona virus Lock down... Unable to obtain any gapped cores.. So I still have to wait.
One of the youtube videos got me to this software
so for the moment I dropped the TI design and tried this new one
Then after soldering complete.. the unit started working...
initial output 12.2volt (no load -- but i have a 100ohm/2watt resister soldered at the output; not included in any load calculations)
Then at 150ma load - 12.0v
500 ma load - 11.6v
900ma - 10.6v
1.5amp - 10.6v
I stopped here.
The software show duty cycle of around 25%
Until then I was using a UC3845 (50% duty cycle)
RT=1nf; CT=9Kohm. => 100 khz (95k to be precise)(It is actually running at 200khz, achieves
the 50% duty cycle by blanking alternate cycles)
so now I changed the CT to 18K and replaced the UC3845 with UC3843 (the 100%
duty cycle one)
I connnected a 60w bulb in series at input , turned the unit on
nothing at the output, the 60w lamp is somewhat bright
Again I replaced things to previous (9k to 18 k ; 3845 to 3845)
now it works.
so what is happening .. the thing is some how working with 3845 as the Duty
cycle is limited to 50%
and when the 3843 is connected it runs at 100% thereby shorting the MOSFET?
The problem is with my transformer..??????
I am planning to use a transformer (for testing ) from already available 3amp supply (chinese RCC)
I have 12v - 1A,2A,3A... with no IC, only transistors.
Anyone know for what frequencies are this transformers designed for?