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Strange Osiloscope Anomaly

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Jwillis:
I'll try to give as much information as I can.
I'm building a powers supply and things are going well but I discovered a weird anomaly on the Output that measures around 40-60 uVpp and I can't pin it down. At first I thought it was an oscillation from one of the op amps but  it's not a consistent oscillation one would expect. It pulses at around 1 second on load and doesn't seem to increase with an increased load.

At the output at  0.1V/Div I get a nice clean DC line  at loads up to 10 Amps at 10 V (haven't gone higher than that ) and about 100mV of ripple at the rectifier which I expected. I need more caps I don't have right now.
But at 20uV/Div this weird pulse shows up. It only appears under load. I changed some caps around the op amps but it doesn't make any difference.Could it be external?

I added a schematic and the best pictures I could of the scope .It's hard to see because it's faint on the scope unless I increase the intensity. And it's hard to take an photo of both channels because of the scan rate between both channels of the scope. 

Kleinstein:
The second scope picture looks like something is oscillating at some times. So the circuit may be just at the edge.
It is odd to see a different picture with the other range.

The load at the output of the voltage regulating OP could be a problem: the OP sees quite some  capacitive load (68 nF in FB) with 100 nF to the output. Not all the capacitance is directly visible, but at the higher frequencies some of it is. So there is a chance the OP could oscillate at least under some load conditions.

The circuit looks like a high current version of the common simple kit. However this circuit is not really that useful at high power, as it does not use tap switching or similar to reduce the power loss. Chances are the transistors would not survive much more than 10 A total at low output voltage due to SOA limitations.  The left 2 OP in the circuit do not have to be expensive high voltage OP. One could power them from a lower supply.
There are few other odd choices (e.g. transistor types).

rdl:
It could be external. Disconnect the scope probes and see if the noise changes or goes away.

Scopes can be good radio receivers at times.   ;D

Andy Watson:
Are the busrts of oscillation synchronised with the mains ? You could try slowing-down the main bridge rectifier by adding 10nF across each diode.

Jwillis:
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.pdf
Thank you for your insight and suggestions.

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