Simple, no-math transformer snubber using Quasimodo test-jig

I could be wrong but it seems a little bit over damped
the target curve should look similar to the red trace in the diagram in post #1
Is this more like it? How do you know when enough is enough? Resistance is 29.8 ohms.
IMG_0135.jpeg
 
..fix this immidiately. (somewhat the last post was incompleted)
Fortunately the AC600V cap was hang in there without any issue.

I temporarily gutted out a same snubber set from another application- which was on a bridge rect., no audiable noise with or without the snubber though -, and used it on this. whew.
 
Hi folks, reading more about the use of the Quasimodo I got the impression that if your transformer has dual secondaries, then you should short not only the primary, but the secondary that is not currently under test. In doing that it reduced the resistance needed. So my current resistor snubber should be about 22 ohms.

Let me know if what I see on the scope meets expectations.

Thanks,

John
 

Attachments

  • IMG_0138.jpeg
    IMG_0138.jpeg
    853.9 KB · Views: 29
You are right. I've read Mark's white paper more than once, but shorting multiple secondaries other than the one under test in addition to the primary did not sink in to my understanding. I'm an implementor, not an engineer. When I read technical papers, my understanding of what I read is often limited by my lack of experience with the subject matter. Fortunately for me there are patient people like you and Mark that get me through.

This snubber exercise is going into my build of a Wolverine amplifier. The amp will have a dual transformers/power supplies. I'm just at the point where I will be testing the IPS and amplifier boards, but I circled back to the power supplies when another generous diyaudio person gifted me the bare Quasimodo pcb.

Thanks for your help with this,

John
 
can anybody help ? trying to find rs value
i have a toroidy supreme audio grade v2 TSAS400 va single 240v 2 x 18v.

i have looked on quasimodo results only.
closest i could find was toroidy audio grade 400va single 230v 2 x 18v.
found 2 different results for the same transformer

cx 10nf , cs150nf , rs 10 ohm

cx 10nf , cs150nf , rs 13 ohm
 
Thank you for the replay. man I realized the problem now.. 150n is rated to DC 1kV..! it’s AC 600V. 10n is AC 1kV… I should
Hi All,
I just finished my Quasimodo and I thought I'd read everything, but I obviously missed the information about the caps... Where can I find this information, or what specifications should each cap have? Thank you in advance.
 
The capacitor needs to be rated appropriately for the expected AC voltage it will be exposed to - for example, if you are using a transformer with 50VAC secondaries, I’d choose a capacitor rated for at least 63VAC… which is to say, AC rating should be somewhat higher than the expected voltage.

Higher voltage rating is fine, of course. Lower voltage rating is to be avoided.
 
  • Like
Reactions: Plott
Hi, well...
I think something went wrong.
I get weird signals...
1. picture: signal on C2
2. picture: signal Quasi output without snubber pot
3. picture: signal Quasi output with snubber pot
I think it's not how it should look 😕

20250516_162736.jpg


20250516_163805.jpg


20250516_163912.jpg