Hi, I have recently built a dc-dc converter to convert supply voltage from 6V to 32V, the circuit diagram is as below:
and the circuit on the breadboard is looks like this:
My friend has built one with the same circuit diagram, I have double checked with him, both circuit connects exactly the same with same components, he circuit is working perfectly fine, but my circuit has a problem. my output voltage jump to the 42V, slowly drops to 32V, jump up again to 42V, slowly drops and it repeats this process over and over again. I have no idea what is wrong with it.
It is not very clear, but make sure the feedback resistors are connected correctly. The connection of R2 to diode and output cap can't be seen clearly on your board.
If I understand the issues with your powersupply, then it is a 10-V ripple. I noticed that the filter caps = 1320uF (220uF + 100uF + 1000uF) but you reduced it to 470uF (less than 37%).
That reduced the time-constant and so the filter caps charges and discharges rapidly creating higher ripples.