Electronics > Projects, Designs, and Technical Stuff
Preventing ringing in audio mute circuit
dmills:
Charge injection?
Place a honking great cap across each of the the LEDs so it fades up and down rather then snapping on or off, and switch LED 2 on before switching led 1 off and vice versa.
Regards, Dan.
David Hess:
It is not clear what is happening so the first thing I would try is AC coupling the optocoupler output and placing a resistor across the optocoupler output so that the capacitor remains charged to the average DC voltage.
Audioguru:
I made background music circuits for speakerphones. To prevent switching the music off at the peak voltage of the signal (causing a loud POP) I slowly ramped on the Jfet used for muting.
I don't know if an optocoupler can slowly ramp on. An old fashioned LDR turns on fairly slowly and might work better.
cvanc:
Just trigger one switch at a time to see if it's only one opto that's causing the issue?
And yeah, maybe stagger the trigger so the shunt element turns on first.
Psi:
I had time today to look into the issue a bit more.
The DC offset idea is defiantly part of the problem, just need to figure out why there's DC where they should not be.
--- Quote from: cvanc on March 23, 2019, 04:58:55 pm ---Just trigger one switch at a time to see if it's only one opto that's causing the issue?
And yeah, maybe stagger the trigger so the shunt element turns on first.
--- End quote ---
It's the Mute opto that's causing the pop
--- Quote from: Audioguru on March 23, 2019, 04:45:10 pm ---I made background music circuits for speakerphones. To prevent switching the music off at the peak voltage of the signal (causing a loud POP) I slowly ramped on the Jfet used for muting.
I don't know if an optocoupler can slowly ramp on. An old fashioned LDR turns on fairly slowly and might work better.
--- End quote ---
Yeah, i may have to do that.
Even with the DC removed i still get a small pop if changing between mute and a peak in the audio.
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