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Simple, no-math transformer snubber using Quasimodo test-jig
Simple, no-math transformer snubber using Quasimodo test-jig
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Old 21st April 2019, 03:44 AM   #1541
dewdrop is offline dewdrop  Singapore
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Simple, no-math transformer snubber using Quasimodo test-jig
On the same token, my mum always tells me to be mindful that being kind or being curt is a fine line depending on how we present it.
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Old 21st April 2019, 01:14 PM   #1542
Johnny Canuck is offline Johnny Canuck  Canada
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Simple, no-math transformer snubber using Quasimodo test-jig
@Dewdrop,
My lack of sophistication in electronics leads me to use X2/Y2 rated safety capacitors in snubbers where I can, since to me they appear to be "across the line", although generally at low voltage where I use them. I think (?) member Jeff Young gently suggested this previously as well (I unabashedly stand on the shoulders of those wiser/smarter than me.)

Is an X2 rating inappropriate or too conservative? Perhaps, but in the case of an over-voltage/over-current event, I have some assurance that they will fail predictably and not start a fire because of their construction.

A disadvantage is that because of their construction, it's hard to find case sizes smaller than pcm 7.5 or 10 for the capacitance values suggested by Quasimodo. And they may be a bit more expensive than non-safety caps.

I have been using Kemet R46 and Rifa PHE840 without event.

Last edited by Johnny Canuck; 21st April 2019 at 01:18 PM.
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Old 21st April 2019, 02:05 PM   #1543
6L6 is offline 6L6  United States
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Simple, no-math transformer snubber using Quasimodo test-jig
Quote:
Originally Posted by dewdrop View Post
Thanks Jim, you are always very kind to all the brands. ;-)
Because in this application there’s absolutely no difference at all. Operational and on-spec is all that matters.
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Old 21st April 2019, 02:58 PM   #1544
dewdrop is offline dewdrop  Singapore
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Simple, no-math transformer snubber using Quasimodo test-jig
Quote:
Originally Posted by Johnny Canuck View Post
@Dewdrop,
My lack of sophistication in electronics leads me to use X2/Y2 rated safety capacitors in snubbers where I can, since to me they appear to be "across the line", although generally at low voltage where I use them. I think (?) member Jeff Young gently suggested this previously as well (I unabashedly stand on the shoulders of those wiser/smarter than me.)

Is an X2 rating inappropriate or too conservative? Perhaps, but in the case of an over-voltage/over-current event, I have some assurance that they will fail predictably and not start a fire because of their construction.

A disadvantage is that because of their construction, it's hard to find case sizes smaller than pcm 7.5 or 10 for the capacitance values suggested by Quasimodo. And they may be a bit more expensive than non-safety caps.

I have been using Kemet R46 and Rifa PHE840 without event.


Thanks Johnny!
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Old 21st April 2019, 03:07 PM   #1545
Mark Johnson is offline Mark Johnson  United States
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Simple, no-math transformer snubber using Quasimodo test-jig
Occasionally I've thought about replacing Cx in a transformer secondary snubber, with a Metal Oxide Varistor. MOVs are overvoltage protection devices, similar to big gigantic bidirectional zener diodes. Because of their large size, big MOVs have lots of capacitance between their terminals. Some datasheets say it's tens of nanofarads. Bingo, right in Cx territory.

Unfortunately, the capacitance of a MOV is nonlinear. It varies with voltage. This makes Quasimodo-style testing a bit more involved, since now you must apply the correct bias voltage to "Cx" while performing the bell-ringing experiments. It's probably possible but undoubtedly messy.

It might be true that using a surge protector outlet strip, between the audio equipment and the AC mains, is easier.
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Old 21st April 2019, 04:26 PM   #1546
phase is offline phase  United States
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Originally Posted by Mark Johnson View Post

It might be true that using a surge protector outlet strip, between the audio equipment and the AC mains, is easier.

I assembled a decent L C filter within a metal cased power strip. It works well, and need to make another one, but the inductor cores had been a common item at Radio Shack, so I need to hunt down a very similar one to use.
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Old 21st April 2019, 06:04 PM   #1547
Mark Johnson is offline Mark Johnson  United States
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Simple, no-math transformer snubber using Quasimodo test-jig
The other end of the spectrum is a G.D.T. (gas discharge tube) whose capacitance is tiny, sub-10pF, because it's just a pair of electrodes in a gas envelope. One of these could connect in parallel with snubbing Cx, and you would simply use Quasimodo in its standard configuration.
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Old 23rd April 2019, 09:29 AM   #1548
kaaang1252oo is offline kaaang1252oo
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nice,
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Old 24th April 2019, 09:56 PM   #1549
darrr is offline darrr  Poland
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Default Simple, no-math transformer snubber using Quasimodo test-jig

Quasimodo is ready for ringing . Now I just need to get an oscilloscope. Thanks Hicoco for the PCB IMG_0002.jpg

Last edited by darrr; 24th April 2019 at 10:09 PM.
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