Its a one second burst/pulse. And it seems to go back to the rectifier after further investigation. Harder to see because it's seems to be imposed on the AC wave .I'm going to set up another transformer later and check the Mains for noise .
The second picture I turned the time/Div higher so I could get a decent picture. That's why the Chan 2 is different from the first picture. I should have mentioned that.
I chose the transistors because at the time the 2SC2922 wasn't obsolete . But the 6 will indeed handle 20 Amps. These are really tough transistors. I have 4 more That I want to add when I can get a larger heat sink.
The other ones were more standard when I started but I found that these worked best and It's what I have on hand without ordering different ones.
Most long duration loading is around 10 to 15 amps with forced air cooling. The 2SC2922 stay at a reasonable temperature at 15 amps . I even had a malfunction with the load and they handled the a full 20 amp short easily for a couple minutes without damage . So I'm not to worried about the power transistors. I plan to make the fans temp controlled but will do that later. As for the expensive op amps I have 50 of them . I'm not worried about that and not intending on putting this thing on any market . Personal use and learning experience only.
Any thing less than the 68nF at the output reg causes severe oscillations to the point of being audible. Surprised the Op amp didn't burn out when that happened.
Getting off the shelf multiple tapped transformers for specific applications is hard unless I get custom made which is expensive. I understand that multi tapped is a more efficient way to go , but not so practical for a simple hobbyist. Besides winding high current toroids by hand is not something I would look forward to doing .But I did have thoughts about using a second or third smaller transformers to switch between. Maybe later.
The design is indeed a variation of a popular kit to resolve some issues that kit had. And it kind of evolved into what I have now. I could go with lower voltages or another proven circuit for sure . That's to easy. I wanted to try something a little different so I can learn from my errors as well as success .
https://www.semicon.sanken-ele.co.jp/sk_content/2sc2922_ds_en.pdfThank you for your insight and suggestions.