Hi guys.
I have spent hours but I cannot figure out what is wrong with the design. The output does not yield anything unless I increase the Boot cap to ridiculous 50uF. The 1:6 ratio still does not give anything remotely close to x6.
Here is the schematic. The duty cycle is near 50%.

 

Divide and conquer.
As a very first step, replace the 1N4148 with a proper fast recovery diode like the UF4007.
Then we’ll start figuring it from there.

Also show the waveforms for Bin and Tin.

 

The 1:6 ratio still does not give anything remotely close to x6.

That's because you do not have a 1:6 turns ratio.
The reflected inductance is proportional to the square of a transformer's turns-ratio, so you need 36mH on the secondary for a 1:6 turns-ratio.

You need to brush-up on your transformer theory.

And a ST noted, the 1n4148 is not appropriate for this application, as it is a small signal diode, not a power rectifier.
Best to use a Schottky rectifier for good efficiency.

 

That's because you do not have a 1:6 turns ratio.
The reflected inductance is proportional to the square of a transformer's turns-ratio, so you need 36mH on the secondary for a 1:6 turns-ratio.

You need to brush-up on your transformer theory.

Thanks! So it is not the same as ferrite cores? I learned something new!!

 

So it is not the same as ferrite cores?

The type of core has nothing to do with it.
That equation is true for all transformers.

 

The type of core has nothing to do with it.
That equation is true for all transformers.

Thanks!! Yes now it gives at least 60v.

 

Divide and conquer.
As a very first step, replace the 1N4148 with a proper fast recovery diode like the UF4007.
Then we’ll start figuring it from there.

Also show the waveforms for Bin and Tin.

Blue is Bin and Red is Tin

 

I suggest that first the TS should verify that there is an alternating voltage across the transformer primary windings.