Quasimodo results (ONLY)

Jump to Latest
JeffYoung

JeffYoung

Member
Joined 2017
Block RKD 160/2X15

Cx 10nF
Cs 150nF
Rs 26Ω


[Data supplied by SGK, http://www.diyaudio.com/forums/powe...using-quasimodo-test-jig-126.html#post5206652 post #253]


Hammond 229C40

Cx 10nF
Cs 150nF
Rs 577Ω

[Data supplied by luvdunhill, post #527]


Hammond 160H12

Cx 10nF
Cs 150nF
Rs 11.5Ω

[Data supplied by luvdunhill, post #528]


Nuvotem 120VA, dual 15V secondaries

Cx 10nF
Cs 150nF
Rs 42.5Ω

Nuvotem 80VA, dual 15V secondaries

Cx 10nF
Cs 150nF
Rs 39Ω

Nuvotem 50VA, dual 15V secondaries

Cx 10nF
Cs 150nF
Rs 38.6Ω

[Data supplied by B&W_arthur, post #351]
 
JeffYoung

JeffYoung

Member
Joined 2017
Triad Magnetics VPT30-5330, dual 15V secondaries

Cx 10nF
Cs 150nF
Rs 22.6Ω

[Data supplied by Mark Johnson, http://www.diyaudio.com/forums/powe...using-quasimodo-test-jig-126.html#post5206652 post #255]


Antek 400VA, 18v

Cx 10nF
Cs 150nF
Rs 18.3Ω

[Data supplied by rickmcinnis, post #978]


R-Core 120VA, dual centre-tapped 18-0-18 secondaries

Cx 10nF
Cs 150nF
Rs 54Ω/54Ω, 69Ω/69Ω

[Data supplied by alexkosha, post #1219]
 
JeffYoung

JeffYoung

Member
Joined 2017
Edcor #XPWR274 (Torpedo and Torpedo III), 200V B+ and 6.3V filament

B+ Cx: 6.8nF
B+ Cs: 68nF
B+ Rs: 760Ω

filament Cx: 10nF
filament Cs: 150nF
filament Rs: 12Ω


Bottlehead PT-10 (SEX), 160V B+ and 6.3V filament

filament Cx: 10nF
filament Cs: 100nF
filament Rs: 9Ω

B+ Cx: 10nF
B+ Cs: 100nF
B+ Rs: 400Ω


Torroidy 300VA, 240V primary, dual 36V secondaries

Cx: 10nF
Cs: 150nF
Rs: 12Ω / 14Ω


Torroidy 500VA, 240V primary, dual 18V secondaries

Cx: 10nF
Cs: 150nF
Rs: 7Ω / 7Ω
 
Mark Johnson

Mark Johnson

Member
Joined 2011
Paid Member
Theoretically it would be possible to write a software "bot" which uses the data contained within these posts, to calculate the transformer secondary's effective leakage inductance. Cx makes it both impossible, and irrelevant, to calculate the secondary's effective self capacitance.
 
KevinHeem

KevinHeem

Member
Joined 2007
Paid Member
JeffYoung said:
Antek 400VA, 18v

Cx 10nF
Cs 150nF
Rs 18.3Ω
Click to expand...

Jeff,
I've tested two Antek AS-4218, and one AN-4218 using the same Cx=10nf, and Cs=150nf. I'm coming up with a way different Rs values than you have posted, but consistent between the three transformers tested. How confident can we be that the values posted in this thread are accurate? I get what you're trying to do here, but I'm encouraging others to build their own Quasimodo/Cheapomodo and verify for themselves.
 
Mark Johnson

Mark Johnson

Member
Joined 2011
Paid Member
Posted 08 December 2018 HERE

_

attachment.php

_
 

Attachments

  • jsjsjsjsjsj.png
    jsjsjsjsjsj.png
    8.3 KB · Views: 3,424
A

audiomusica

Member
Joined 2014
Talema 2x115V, 2x7V, 2x12,5VA


Primaries in series for 230V operation and shorted (for snubbing)
Secondaries in parallel


Cs=150nF, Cx=10nF -> fosc ~ 625kHz(!)



Snubbing this small print torodial transformer I get values for Rs ~ 12Ohm.


Are such low values for Rs reasonable?
 

Attachments

  • IMG_6530.jpg
    IMG_6530.jpg
    327.7 KB · Views: 1,698
Mark Johnson

Mark Johnson

Member
Joined 2011
Paid Member
Audiomusica, since you doubt your experimental results from No-Math Quasimodo, you have no other choice than to use math for verification.

Your numerical values of fosc (6.25E+5) and Cx (1.0E-8) indicate that the secondary self inductance L is about (6.5E-6) Henrys. We calculate L using the LC resonance equation.

The LC resonance equation: 2 * Pi * fosc = 1 / sqrt(L * C)​

Plugging this value for L into equation (A.11) of the Quasimodo design note, we find

R < 12.7 ohms​

Which seems to be in broad agreement with your experimental results. You were wrong to doubt them.
 
You must log in or register to reply here.
Top Bottom