I'd like to mute 6 channels of audio for about 10 seconds at power-on without having a 2 or 3 electromechanical relays. I plan to short the output for this duration. Has anybody seen or used something like analog switches (e.g. 4066 or higher quality versions) to do muting?
Thanks in advance for your suggestions.
Thanks in advance for your suggestions.
Analog optocouplers are also nice depending on your needs - about $3 ea. from Allied. For audio application notes see:
http://www.silonex.com/audiohm/index.html
Phil
http://www.silonex.com/audiohm/index.html
Phil
merry christmas to this forum!
i highly recommend to use relays for muting!!!!!!!
by my experience solid states devices tends to alter in any
manner the audio,specially hi-end systems!
last week i modified my cd player eliminating the transistorizied muting & emphasis circuitry with relays (difference was huge)
if u are still interested with transistors ,let me know & tell you
how was configured my player.
or stick to digikey catalog that they have very good realys
ex. 8 contacts in one only package)
thank you
richt
i highly recommend to use relays for muting!!!!!!!
by my experience solid states devices tends to alter in any
manner the audio,specially hi-end systems!
last week i modified my cd player eliminating the transistorizied muting & emphasis circuitry with relays (difference was huge)
if u are still interested with transistors ,let me know & tell you
how was configured my player.
or stick to digikey catalog that they have very good realys
ex. 8 contacts in one only package)
thank you
richt
For those who are lazy, Potter & Brumfeld used to (probably still do) have relays that you buy off the shelf with set time delays.
When I bother with such things, I use an antique idea based on a unijunction transistor that triggers an SCR that triggers a relay. Unijunctions are worse than hens' teeth now for availability, so the next time I do something of that nature, I'll probably use something like a 555 timer to trigger the SCR. Not all that difficult to do.
Nelson burns off out-of-spec MOSFETs (at least I assume they didn't make the cut, it's what I'd do in his position to keep costs down) in a cute little one-two punch to trigger a relay. Check out the...duh, I forgot...maybe the Aleph Ono schematic, I think. Couple of resistors, couple of diodes, couple of MOSFETs and a cap. Nuthin' to it.
I've seen lots of variations on the resistor & cap time constant to the base/gate of a transistor to do a solid state mute here and there, but for the life of me can't remember where I saw the last one. If my memory unclogs, I'll post a link.
Grey
When I bother with such things, I use an antique idea based on a unijunction transistor that triggers an SCR that triggers a relay. Unijunctions are worse than hens' teeth now for availability, so the next time I do something of that nature, I'll probably use something like a 555 timer to trigger the SCR. Not all that difficult to do.
Nelson burns off out-of-spec MOSFETs (at least I assume they didn't make the cut, it's what I'd do in his position to keep costs down) in a cute little one-two punch to trigger a relay. Check out the...duh, I forgot...maybe the Aleph Ono schematic, I think. Couple of resistors, couple of diodes, couple of MOSFETs and a cap. Nuthin' to it.
I've seen lots of variations on the resistor & cap time constant to the base/gate of a transistor to do a solid state mute here and there, but for the life of me can't remember where I saw the last one. If my memory unclogs, I'll post a link.
Grey
Grey
Thanks for the tip on the relay + delay on the Aleph Ono -- that is cute! I wish I had seen it earlier. I'm building 555-delayed relays for soft-starts for Parasound 3500s but the Pass MOSFET circuit would have given me a lot more flexibility in where I pick off the power for the delay circuit.
Thanks again
Phil
Thanks for the tip on the relay + delay on the Aleph Ono -- that is cute! I wish I had seen it earlier. I'm building 555-delayed relays for soft-starts for Parasound 3500s but the Pass MOSFET circuit would have given me a lot more flexibility in where I pick off the power for the delay circuit.
Thanks again
Phil
You talkin' to me?GRollins said:
Seriously, I've discovered the 4541 CMOS circuit for any time delay stuff and won't go back to 555s or anything else. Datasheet's a bit opaque but the part itself is versatile and accurate. I'll probably use it for this application with a cheap TIP14x Darlington transistor to drive the relay.
Check it out:
http://www.semiconductors.philips.com/pip/hef4541bp
Hey, being lazy is good engineering practice, it involves thinking before doing...
Hey, why would anybody want to talk to you -- you only started this topic! 
Thanks for the tip on the 4541 -- it looks good. I'll have some applications for it but I'm not sure I agree with all you've said.
The 555 takes no more parts to implement as a delay than the 4541 plus it can source/sink up to 200 mA which often eliminates the need for a pass transistor, although I usually use one based on the belt and suspenders philosophy. It's also cheap, and isn't cost-effectiveness also a good engineering principle? (Besides, I have a bunch of them I inherited from somewhere that I want to use up). This is mostly tongue-in-cheek --- we're talking about pretty small differences here, aren't we, especially for those building onesies or twosies of something. But I believe that Thomas Edison was the first to comment on the benefits of laziness.
I guess the one thing that would bother me about the 4541 for my present application is the built-in oscillator. I run an all-analog system most of the time and keep any clocks or digital oscillators out of my equipment, even if they're not directly in the audio circuit. Maybe just superstition.
Anyway, time to stop yackin' and start soldering and finally finish those delay boards like I promised myself. Thanks again for pointing out 4541 (I wish I had known about them earlier) and for starting this post. It's been interesting especially since I've been thinking about this kind of stuff recently. Good luck with the project!
Phil
Thanks for the tip on the 4541 -- it looks good. I'll have some applications for it but I'm not sure I agree with all you've said.
The 555 takes no more parts to implement as a delay than the 4541 plus it can source/sink up to 200 mA which often eliminates the need for a pass transistor, although I usually use one based on the belt and suspenders philosophy. It's also cheap, and isn't cost-effectiveness also a good engineering principle? (Besides, I have a bunch of them I inherited from somewhere that I want to use up). This is mostly tongue-in-cheek --- we're talking about pretty small differences here, aren't we, especially for those building onesies or twosies of something. But I believe that Thomas Edison was the first to comment on the benefits of laziness.
I guess the one thing that would bother me about the 4541 for my present application is the built-in oscillator. I run an all-analog system most of the time and keep any clocks or digital oscillators out of my equipment, even if they're not directly in the audio circuit. Maybe just superstition.
Anyway, time to stop yackin' and start soldering and finally finish those delay boards like I promised myself. Thanks again for pointing out 4541 (I wish I had known about them earlier) and for starting this post. It's been interesting especially since I've been thinking about this kind of stuff recently. Good luck with the project!
Phil
Thinking...?
Whuzzat?
I've never bothered to come up with an original delay-relay circuit because so many people have solved the problem so nicely in the past. Saves brain cells (& time) for other things.
If I have seen further, it is by standing upon the shoulders of Giants...
Sir Isaac Newton
Grey
Whuzzat?
I've never bothered to come up with an original delay-relay circuit because so many people have solved the problem so nicely in the past. Saves brain cells (& time) for other things.
If I have seen further, it is by standing upon the shoulders of Giants...
Sir Isaac Newton
Grey
I've built a small board for my amp, containing two led vu-meter chips and two of Rod Elliots' "Loudspeaker protection and muting" designs... this is a very simple circuit, and as far as i've tested it, it works flawlesly. It'll drop the relays if any DC is present at the input and you can also set up a turn-on delay and inmediate turn-off muting to kill the transients. I just added some minor mods (one circuit per channel, ability to mute from a switch and a led indicator to match the nifty vumeters ). Highly reccomended.
). Highly reccomended.
AudioFreak said:
You mean the relay relaiabilty issue i presume... well, i'm using a pair of SPST Goodsky relays rated at 10A 30VDC (about $4 each). I once opened one and the contact area is a solid disc of some material i can't identify (seems like a gold alloy), so i presume they can take small DC arcs without problems. My amp is 2x20w, so i have quite a safety margin. I haven't had a chance to measure the switching time, but the switching itself is INAUDIBLE; guess that's good enough.
I strongly reccomend using relays for output muting. Good relays are not that expensive or uncommon, and from previous experiences, they're can be very rugged and have a long life. The Elliot project for muting and DC protection can be built for about $20, what do you have to loose?
Lisandro....
What do you have to lose? how bout the amp and speakers.
The arc is potentially huge and can/will easily weld the contacts which can then lead to a totally dead amp and fried speakers.
The relays are great for turn-on/off muting but this is where their use should finish ... a crowbar circuit should be used for DC protection as a relay will easily be arc welded when used in the protection circuit.
What do you have to lose? how bout the amp and speakers.
The arc is potentially huge and can/will easily weld the contacts which can then lead to a totally dead amp and fried speakers.
The relays are great for turn-on/off muting but this is where their use should finish ... a crowbar circuit should be used for DC protection as a relay will easily be arc welded when used in the protection circuit.
A constant magnetic field (such as the Earth's--if you're going to worry about 'DC' magnetic fields, don't forget that one) will not have an effect on the current in a wire. Only a varying magnetic field will create a current in a wire.
Relays do sometimes have problems, but rarely. At the moment, I can only remember seeing one welded relay and it was smaller than I would have liked to have seen. Crowbar circuits aren't perfect, either. For that matter some people seem congenitally unable to drive a car safely. Does that mean no one should drive a car?
Grey
Relays do sometimes have problems, but rarely. At the moment, I can only remember seeing one welded relay and it was smaller than I would have liked to have seen. Crowbar circuits aren't perfect, either. For that matter some people seem congenitally unable to drive a car safely. Does that mean no one should drive a car?
Grey
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