This is an example of a power supply. With the component values shown and the transformer design shown on page two it operates over an input range of 80 to 265 VAC. We would like this design to operate with lower input voltages. We would like it to operate with an input voltage of 48 VDC.

I have made one change that drops the input voltage requirement. That is to short out R500 and R501. With these resistors shorted out the input requirement drops to about 52 VAC.

I have also tried shorting out transformer primary turns on wdg #9. This prevents the power supply from operating at all.

So I would like to either make a value change or even a transformer change that would allow this supply to operate at 48 VDC +/- 10%..

thanks, Mike