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Hoffman Amps Forum image Author Topic: Temporarily muting signal while changing channels.  (Read 3823 times)

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Offline Captain chunkulus

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Temporarily muting signal while changing channels.
« on: December 07, 2019, 09:22:22 pm »
Any of you guys know a simple way temporarily mute a signal while changing channels so the relays don't pop while changing channels? Thanks.

Offline DummyLoad

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Re: Temporarily muting signal while changing channels.
« Reply #1 on: December 07, 2019, 09:37:58 pm »
cascaded 555 timers configured as one-shots. the first 555 mutes, the second 555 switches. the first timers' time constant longer than the second. ~250ms to mute 100ms switch. better yet; use vactrol opto coupled varistors, such as the VTL5C3, etc..


--pete

Online pdf64

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Re: Temporarily muting signal while changing channels.
« Reply #2 on: December 08, 2019, 02:32:29 am »
Better to minimise / cure the ‘pop’ rather than introduce momentary muting circuits?
https://www.justgiving.com/page/5-in-5-for-charlie This is my step son and his family. He is running 5 marathons in 5 days to support the research into STXBP1, the genetic condition my grandson Charlie has. Please consider supporting him! BBC News feature  https://www.bbc.co.uk/news/articles/cm26llp

Offline Captain chunkulus

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Re: Temporarily muting signal while changing channels.
« Reply #3 on: December 08, 2019, 08:15:06 am »
Better to minimise / cure the ‘pop’ rather than introduce momentary muting circuits?

This seems better to me. I already have relays installed that are switching the channels and such. Just get popping when changing channels. Any simple fixes for this?

Offline jjasilli

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Re: Temporarily muting signal while changing channels.
« Reply #4 on: December 08, 2019, 09:08:16 am »
Yes, a time delay works, but is not optimal especially when playing live.  One solution may be a 1M R across the SW section of the relay.  This also works for manual SW's.  Another possibility is a snubber diode circuit:  https://en.wikipedia.org/wiki/Flyback_diode


Also see the annexed files.

Offline d95err

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Re: Temporarily muting signal while changing channels.
« Reply #5 on: December 08, 2019, 10:58:15 am »
Better to minimise / cure the ‘pop’ rather than introduce momentary muting circuits?

This seems better to me. I already have relays installed that are switching the channels and such. Just get popping when changing channels. Any simple fixes for this?

If you post schematic, it will be easier to help you.

As for a temporary mute circuit, a simple solution using a fet and rc network triggered by the relay switching is used by some manufacturers. I think Engl amps has this.

Offline kagliostro

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Re: Temporarily muting signal while changing channels.
« Reply #6 on: December 08, 2019, 11:51:00 am »
This unit is to be put in parallel with the contact of the switch (done for solve your kind of problems - didn't has a high price)






Expecially Read this (and other link)
http://www.kemet.com/Lists/ProductCatalog/Attachments/146/F9000_GenInfo_RCUnits.pdf



https://it.rs-online.com/web/p/condensatori-per-reti-rc/0209213/

http://el34world.com/Forum/index.php?topic=14021.ms

Franco
« Last Edit: December 08, 2019, 01:39:01 pm by kagliostro »
The world is a nice place if there is health and there are friends

Offline Captain chunkulus

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Re: Temporarily muting signal while changing channels.
« Reply #7 on: December 08, 2019, 01:36:28 pm »
Better to minimise / cure the ‘pop’ rather than introduce momentary muting circuits?

This seems better to me. I already have relays installed that are switching the channels and such. Just get popping when changing channels. Any simple fixes for this?

If you post schematic, it will be easier to help you.

As for a temporary mute circuit, a simple solution using a fet and rc network triggered by the relay switching is used by some manufacturers. I think Engl amps has this.

What is an example circuit for the fet/rc network your talking about? Is this it basically?
« Last Edit: December 08, 2019, 01:38:56 pm by Captain chunkulus »

Online pdf64

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Re: Temporarily muting signal while changing channels.
« Reply #8 on: December 08, 2019, 05:32:19 pm »
What is popping - The coil or the audio switched circuit?
The back emf of a dc coil is best de energised with diode; RC snubbers are used for ac coils.
https://www.justgiving.com/page/5-in-5-for-charlie This is my step son and his family. He is running 5 marathons in 5 days to support the research into STXBP1, the genetic condition my grandson Charlie has. Please consider supporting him! BBC News feature  https://www.bbc.co.uk/news/articles/cm26llp

Offline Captain chunkulus

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Re: Temporarily muting signal while changing channels.
« Reply #9 on: December 08, 2019, 05:44:51 pm »
Well, I'm using a dc supply for the relays and a mechanical switch to make and break the connection to the negative side of the supply.

Online pdf64

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Re: Temporarily muting signal while changing channels.
« Reply #10 on: December 09, 2019, 04:50:05 am »
A dc relay coil needs a (reverse biased) diode connected across it (or between the switched coil end and circuit common), fitted in close proximity.
Any regular power diode should do the job, but as they’re cheap and readily available, these days I’d use UF4007.
The big advantage of dc relays in this application is that its back emf spike can be so easily and effectively mitigated (ie compared to ac coils).
« Last Edit: December 09, 2019, 05:52:09 am by pdf64 »
https://www.justgiving.com/page/5-in-5-for-charlie This is my step son and his family. He is running 5 marathons in 5 days to support the research into STXBP1, the genetic condition my grandson Charlie has. Please consider supporting him! BBC News feature  https://www.bbc.co.uk/news/articles/cm26llp

Offline d95err

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Re: Temporarily muting signal while changing channels.
« Reply #11 on: December 09, 2019, 06:09:07 am »
Well, I'm using a dc supply for the relays and a mechanical switch to make and break the connection to the negative side of the supply.

Again, without a schematic it's difficult to help you.

Doesn't have to be fancy. Make a simple drawing on paper and take a photo with your phone, then upload here.

Offline sluckey

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Re: Temporarily muting signal while changing channels.
« Reply #12 on: December 09, 2019, 06:24:11 am »
+1
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

 


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