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

[jminassi]

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.

 

[trobbins]

Is you cap rating 1kVac or 1kVdc ?

 

[hayunart]

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

 

[hayunart]

..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.

 

[jminassi]

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

 

[trobbins]

There are past comments on the default shorting of the untested secondary, compared to iteratively fitting a C-RC snubber in lieu of a short, as that is what be installed in-situ.

 

[jminassi]

Indeed there is information on the default shorting of untested secondaries. Weeding through over 2,600 comments to find it is the problem I have....,,

 

[trobbins]

post 2368 is one example. https://www.diyaudio.com/community/...-using-quasimodo-test-jig.243100/post-7247275

 

[jminassi]

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

 

[poolball69]

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

 

[6L6]

Anything you have from 10-20ohm will work beautifully. Use what you've got on hand. 😎

 

[poolball69]

hi 6L6 , thanks for your reply. I dont have any 10-20ohm need too buy.
There is quite a few values between 10 - 20ohm, what should i get 15ohm ?

thanks magnus

 

[6L6]

That will work wonderfully.

 

[poolball69]

Cool will buy 15 ohm .

thanks