retrofitting an auto-mute volume control?
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From: whit3rd on 12 Dec 2009 20:57 On Dec 12, 3:31 pm, Jon Kirwan <j...(a)infinitefactors.org> wrote: > >And yes, if I could lock down a remote control device I build so that > >it points at the TV set supporting it, that could work. I'm thinking more of a central point in the house that generates a steady stream of 'volume-slightly-down' commands, and using wiring (like, the black/yellow pair on telephone connectors) to run to each room, and blast out the codes in all directions. The central controller eventually turns the volume all the way down, but not by a single 'mute' step. And, it has its own IR emitters, there's no interaction with any handheld remote control option.
From: Jon Kirwan on 12 Dec 2009 21:01 On Sat, 12 Dec 2009 19:41:58 -0600, "Tim Williams" <tmoranwms(a)charter.net> wrote: >"Jon Kirwan" <jonk(a)infinitefactors.org> wrote in message >news:ne48i5d7bffiq5c1cvt7nbbnrq3ljtlj53(a)4ax.com... >> Detection remains a problem here. Often, she lies down and doesn't >> move -- either awake or asleep. Too many false positives and we'd >> learn to ignore it. > >Would it do to have a camera mounted fairly low, so that continuous motion >only in the lower half of the image corresponds to a siezure? This also >assumes she isn't constantly moving around when lying down, of course the >magnitude of motion could be controlled too. Interesting questions. Some hours of each day, she just goes into her room and lays down under a blanket and looks at the ceiling, laughs a bit, rolls over, etc. Assume there is a camera mounted there. If she has a seizure during her sleep (very rare, as it is almost always within about 1.5 to 2 hours within waking up), that might work. But she plays, too. Besides, her seizing when under a blanket is not the kind of "wild flapping" that you see on TV, sometimes. It's as though all of her muscles are tightened up -- she feels like a solid rock -- and she is shaking somewhat. There is NO oxygen getting into her blood, so she damages her brain if it lasts too long. It is very tense, low-motion, and she can grind (destroy, even) her teeth in the process or cut her tongue in half if her jaw clenches down hard instead of up. Sometimes, the jaw opens and closes. Sometimes, it is stuck open or stuck closed. Sometimes, that changes during the seizure. But by and large, not a lot of motion. Just a sudden high tightness tensing of muscles and fairly low-intensity motions that last for between one minute and as much as four. Which reminds me... a pulse-ox might be appropriate for detection after the fact. Oxygenation levels should drop precipitously. And these are dirt cheap, nowadays, and not hard to develop either. Of course, it doesn't solve the detection problem until after it is way too late. But it would make sure we know close to 100% of the time when one happens. And that has value, too. We do have, sometimes, some indications 10 or 20 minutes early. A kind of spasmatic jerk in her hands and shoulders that isn't visibly noticeable, but if you are holding her you can feel them. They are an indication that we are within an hour or so and that can allow is to dose her before it happens or to at least hover and be there at the right time. My instincts tell me to hold off of using video processing, for now. Difficult and expensive for all the needed coverage areas, processing complexities, etc. I need to explore other solutions that I can 'see' the other end of more readily, first. I'd also still like to try out an auto-mute or two, as well. Those aren't more direct detection, but they enable our own ears and that's also important. The twin approaches... auto-mute and direct detection on her body are like playing this from two ends to the middle. On one end, there is our own fine-tuned detection (ears and brain) where the auto-mute helps us; and on the other end there is the direct detection that provides an entirely different pathway for detection and can be made to reach us by altering the 'signal' so that we definitely notice it. Jon
From: Jon Kirwan on 12 Dec 2009 21:33 On Sat, 12 Dec 2009 17:57:35 -0800 (PST), whit3rd <whit3rd(a)gmail.com> wrote: >On Dec 12, 3:31�pm, Jon Kirwan <j...(a)infinitefactors.org> wrote: > >> >And yes, if I could lock down a remote control device I build so that >> >it points at the TV set supporting it, that could work. > >I'm thinking more of a central point in the house that generates a >steady stream of 'volume-slightly-down' commands, and using >wiring (like, the black/yellow pair on telephone connectors) to >run to each room, and blast out the codes in all directions. > >The central controller eventually turns the volume all the way down, >but not by a single 'mute' step. And, it has its own IR emitters, there's >no interaction with any handheld remote control option. Egads. I think I'm not quite ready for all that, just yet. And even then, it's only a partial solution as it only handles those cases where IR emitters are useful. I may get there someday? Hopefully, the seizures will just stop or else we will outfit her with a medical device to halt them. (There are two such things available as I speak, which may or may not yield results for us when and if we decide to try them. One is a vagal nerve stimulator and another is actually placed into the brain, itself.) Short of that kind of cessation or cessation because of death, the right solution is surrounding her by a knowledgeable human community, good record keeping, and appropriate physical, technical and chemical adjustments. The balance in all that is a path one walks and not a destination one can ever hope to ultimately reach. Jon
From: ehsjr on 13 Dec 2009 00:14 Jon Kirwan wrote: > On Sat, 12 Dec 2009 16:46:21 -0500, ehsjr <ehsjr(a)nospamverizon.net> > wrote: > > >>Jon Kirwan wrote: >> >>>To start off, I'm not looking for a specific design, though of course >>>I will be very happy for any such attempts. I'd like some thoughts >>>about approaches or problems I may need to consider. I'd be happy to >>>then expose some design I come up with, to criticism. >>> >>>I need an auto-mute circuit that I can use to retrofit devices that >>>provide an amplified audio output to a speaker or speaker pair. These >>>include television sets which use UP/DOWN buttons to set volume all >>>the way to resistor-based knobs and wheels that set volume. >>> >>>I could consider not "getting everything" and instead just focusing >>>only on those devices which use a resistor to control the volume, >>>interceding at that point (using the existing control but adding a >>>circuit around it.) In that case, the circuit would need to behave >>>the same regardless of which resistive 'end' was used to set the >>>highest volume. I'd like to handle TV sets that use UP/DOWN buttons, >>>too. But even _some_ solutions are better than none. >>> >>>By 'retrofit' I mean that I cannot add new control systems to existing >>>ones by drilling holes and making the operation more complex to handle >>>-- the operation must be fully automatic and set by me _before_ I open >>>up the units and insert the circuit, without having to create any >>>external access holes or buttons, etc. >>> >>>My daughter has grand mal seizures that my wife and I need to hear the >>>beginnings of. My daughter loves to turn on stereo systems and music >>>boxes, quite loud at times. She enjoys listening and often has her >>>computer software playing something loud while having a CD player >>>playing something else in the same room, while still something else is >>>playing on a CD player in the next room, as well. We don't want to >>>take that away from her, but it also makes for a noisy environment >>>which can easily mask our ability to detect a seizure as early as we'd >>>like to. The results of our missing the early sounds of a seizure >>>event could potentially lead to broken arms, or even death in an >>>extreme case. So this can have very important consequences. >>> >>>We've used timers on the power plugs. But besides the fact that she >>>moves things around from place to place if it "doesn't work" from her >>>point of view, using a timer greatly complicates our own life. She >>>needs to have the ability to initiate the operation by using controls >>>that already exist on the device. (She is 25 years old, but operates >>>much like a 4 year old. She can learn some things, like how to turn >>>the volume control knob, but using timer boxes greatly complicates >>>operation and thus greatly complicates both her and our lives.) >>> >>>What I need is something that doesn't increase the complexity of her >>>use of the device. She simply needs to learn to "adjust the volume" >>>as she always does to cause the mute operation to cease, instantly. >>>But that action should initiate the start of a new timing cycle. The >>>auto-mute effect needs to take place after about 10 minutes of use, >>>but I'd like to be able to set that range from perhaps 1 minute to 15 >>>minutes. That said, to be completely honest about it, I could live >>>with a fixed 10-minute delay. >>> >>>The power source is an issue. These devices I'd modify _do_, of >>>course, have internal power supplies and I could scarf around to find >>>something to attach to, of course. How the ground will relate to the >>>speakers, I don't know. It may depend on the device. The speaker >>>outputs may even be galvanically isolated. Best would be that energy >>>is derived from the sound system's own delivered power to the >>>speakers, so that it's 'universal' in that regard. This would save me >>>from replacing batteries or having to make custom designs for each and >>>every situation's internal supply modifications. (While the voltage >>>is building up in such a case, though, I'd like the unpowered circuit >>>situation to be 'unmuted.') But battery powered, if necessary, is >>>acceptable if I don't have to replace them more often than once every >>>few months and so long as I'm able to fit the battery system inside >>>(in some cases, that will be 'hard'.) >>> >>>What would work best for her is that if she 'fiddles' with the volume >>>control, the mute operation ceases and the timer starts. >>> >>>This needs to work on CD and karaoke players, stereo and mono >>>amplifiers, TVs, etc. Almost all are wall-plug powered. Not all, >>>though. Some use multiple D-cells ('boom boxes') or allow an >>>'either-or' operation, using batteries if unplugged from the wall. >>> >>>I've only just begun to think about this and my own limitations in >>>experience are suddenly in evidence to me. My first thought would >>>only work on the resistive type controls, would use a micro to monitor >>>the value (ADC) and then control a digital POT I select. It would >>>need power but I could use an MSP430 to mitigate that problem, using a >>>small CR2025 or CR2032 which would last quite a while. (The timing >>>requirement of minutes, alone, almost forces me to think in terms of a >>>micro, though I can think of a few analog circuits using a cap and >>>mosfet that would handle such times.) I would probably need custom >>>programming, a tweak for the input gain perhaps, and perhaps a >>>different digital POT for each unit I modified. But at least I can >>>see how to handle that. >>> >>>Thoughts and criticisms meant constructively are appreciated. >>> >>>Jon >> >>Let me see if I understand the functional requirements: >>1) Every X minutes, mute the device >>2) Un-mute it when the volume control is fiddled >> >>Is that exactly what you want in terms of function, >>ignoring the technical requirements (no holes, power >>supply considerations, the muting device or circuit >>needs to work with several different pieces of equipment, >>whatever)? > > > Yes. That pretty much nails what I'd like to try out, right now. > > As should be abundantly clear, we are hacking out new territory and > always experimenting to improve the quality of our results with her. > So once we field something, we may discover new effects to worry > about. > > It's kind of like the "theory of pendulums." You can start out very > neatly describing the motion, constraining the swing such that sin > theta = theta to a reasonable approximation to eliminate confounding > terms, and yield the well known pendulum law. However, when you start > actually _building_ pendulums and when you improve your measurement > precision of the timing over time, you find the theory doesn't take > into account the diameter of the holes that rock on the pins you > build, relative to each other, which can affect the predictions by 2 > or 3 percent or more -- which cannot be explained by timing > measurement errors alone. So you search out this new effect, discover > it, and then want to deal with it, too. > > I expect that once we get this working, what is currently obfuscated > by the magnitude of the current problem will be stripped away to view > and we'll probably have some new thoughts to add, then. For now, I > can't see any of that so this is exactly what I'm looking for. > > It goes in incremental steps. Like life. > > Jon Two things: first, separate the life condition from the functional requirements you present here. That means you want a circuit that does: 1) Every X minutes, mute the device 2) Un-mute it when the volume control is fiddled That is the only functional requirement set we (responders) should address. We are not capable of knowing whether it will address the life situation, and not professionals on the medical side of things. Second thing: to meet 1 & 2 above one general approach that might fit is as follows. Put DC and signal on the volume pot - the wiper will give you a DC voltage as well as the signal. Use a cap to bring the ac to the amplifying stages, blocking the DC. Run the DC from the wiper through an R to a small 'lytic which will charge to the level at the wiper. (A sort of poor man's sample & hold.) The cap connects to one input of a comparator. The input goes to the wiper through an identical R with no cap. Use enough hysteresis to accomodate slight difference in the DC applied to the inputs. The output of the comparator resets the ten minute timer. The timer gates the audio out to the speakers. I see plenty of possible downside to the above - it requires "surgery" to each device, which may make it a non-starter. It also operates for only one direction of the volume control, and it is only conceptual - you would have to flesh it out. But it is one idea you could experiment with, and the power source is already inside the equipment. Ed
From: Jon Kirwan on 13 Dec 2009 02:27
On Sun, 13 Dec 2009 00:14:17 -0500, ehsjr <ehsjr(a)nospamverizon.net> wrote: >Jon Kirwan wrote: >> On Sat, 12 Dec 2009 16:46:21 -0500, ehsjr <ehsjr(a)nospamverizon.net> >> wrote: >> >> >>>Jon Kirwan wrote: >>> >>>>To start off, I'm not looking for a specific design, though of course >>>>I will be very happy for any such attempts. I'd like some thoughts >>>>about approaches or problems I may need to consider. I'd be happy to >>>>then expose some design I come up with, to criticism. >>>> >>>>I need an auto-mute circuit that I can use to retrofit devices that >>>>provide an amplified audio output to a speaker or speaker pair. These >>>>include television sets which use UP/DOWN buttons to set volume all >>>>the way to resistor-based knobs and wheels that set volume. >>>> >>>>I could consider not "getting everything" and instead just focusing >>>>only on those devices which use a resistor to control the volume, >>>>interceding at that point (using the existing control but adding a >>>>circuit around it.) In that case, the circuit would need to behave >>>>the same regardless of which resistive 'end' was used to set the >>>>highest volume. I'd like to handle TV sets that use UP/DOWN buttons, >>>>too. But even _some_ solutions are better than none. >>>> >>>>By 'retrofit' I mean that I cannot add new control systems to existing >>>>ones by drilling holes and making the operation more complex to handle >>>>-- the operation must be fully automatic and set by me _before_ I open >>>>up the units and insert the circuit, without having to create any >>>>external access holes or buttons, etc. >>>> >>>>My daughter has grand mal seizures that my wife and I need to hear the >>>>beginnings of. My daughter loves to turn on stereo systems and music >>>>boxes, quite loud at times. She enjoys listening and often has her >>>>computer software playing something loud while having a CD player >>>>playing something else in the same room, while still something else is >>>>playing on a CD player in the next room, as well. We don't want to >>>>take that away from her, but it also makes for a noisy environment >>>>which can easily mask our ability to detect a seizure as early as we'd >>>>like to. The results of our missing the early sounds of a seizure >>>>event could potentially lead to broken arms, or even death in an >>>>extreme case. So this can have very important consequences. >>>> >>>>We've used timers on the power plugs. But besides the fact that she >>>>moves things around from place to place if it "doesn't work" from her >>>>point of view, using a timer greatly complicates our own life. She >>>>needs to have the ability to initiate the operation by using controls >>>>that already exist on the device. (She is 25 years old, but operates >>>>much like a 4 year old. She can learn some things, like how to turn >>>>the volume control knob, but using timer boxes greatly complicates >>>>operation and thus greatly complicates both her and our lives.) >>>> >>>>What I need is something that doesn't increase the complexity of her >>>>use of the device. She simply needs to learn to "adjust the volume" >>>>as she always does to cause the mute operation to cease, instantly. >>>>But that action should initiate the start of a new timing cycle. The >>>>auto-mute effect needs to take place after about 10 minutes of use, >>>>but I'd like to be able to set that range from perhaps 1 minute to 15 >>>>minutes. That said, to be completely honest about it, I could live >>>>with a fixed 10-minute delay. >>>> >>>>The power source is an issue. These devices I'd modify _do_, of >>>>course, have internal power supplies and I could scarf around to find >>>>something to attach to, of course. How the ground will relate to the >>>>speakers, I don't know. It may depend on the device. The speaker >>>>outputs may even be galvanically isolated. Best would be that energy >>>>is derived from the sound system's own delivered power to the >>>>speakers, so that it's 'universal' in that regard. This would save me >>>>from replacing batteries or having to make custom designs for each and >>>>every situation's internal supply modifications. (While the voltage >>>>is building up in such a case, though, I'd like the unpowered circuit >>>>situation to be 'unmuted.') But battery powered, if necessary, is >>>>acceptable if I don't have to replace them more often than once every >>>>few months and so long as I'm able to fit the battery system inside >>>>(in some cases, that will be 'hard'.) >>>> >>>>What would work best for her is that if she 'fiddles' with the volume >>>>control, the mute operation ceases and the timer starts. >>>> >>>>This needs to work on CD and karaoke players, stereo and mono >>>>amplifiers, TVs, etc. Almost all are wall-plug powered. Not all, >>>>though. Some use multiple D-cells ('boom boxes') or allow an >>>>'either-or' operation, using batteries if unplugged from the wall. >>>> >>>>I've only just begun to think about this and my own limitations in >>>>experience are suddenly in evidence to me. My first thought would >>>>only work on the resistive type controls, would use a micro to monitor >>>>the value (ADC) and then control a digital POT I select. It would >>>>need power but I could use an MSP430 to mitigate that problem, using a >>>>small CR2025 or CR2032 which would last quite a while. (The timing >>>>requirement of minutes, alone, almost forces me to think in terms of a >>>>micro, though I can think of a few analog circuits using a cap and >>>>mosfet that would handle such times.) I would probably need custom >>>>programming, a tweak for the input gain perhaps, and perhaps a >>>>different digital POT for each unit I modified. But at least I can >>>>see how to handle that. >>>> >>>>Thoughts and criticisms meant constructively are appreciated. >>>> >>>>Jon >>> >>>Let me see if I understand the functional requirements: >>>1) Every X minutes, mute the device >>>2) Un-mute it when the volume control is fiddled >>> >>>Is that exactly what you want in terms of function, >>>ignoring the technical requirements (no holes, power >>>supply considerations, the muting device or circuit >>>needs to work with several different pieces of equipment, >>>whatever)? >> >> >> Yes. That pretty much nails what I'd like to try out, right now. >> >> As should be abundantly clear, we are hacking out new territory and >> always experimenting to improve the quality of our results with her. >> So once we field something, we may discover new effects to worry >> about. >> >> It's kind of like the "theory of pendulums." You can start out very >> neatly describing the motion, constraining the swing such that sin >> theta = theta to a reasonable approximation to eliminate confounding >> terms, and yield the well known pendulum law. However, when you start >> actually _building_ pendulums and when you improve your measurement >> precision of the timing over time, you find the theory doesn't take >> into account the diameter of the holes that rock on the pins you >> build, relative to each other, which can affect the predictions by 2 >> or 3 percent or more -- which cannot be explained by timing >> measurement errors alone. So you search out this new effect, discover >> it, and then want to deal with it, too. >> >> I expect that once we get this working, what is currently obfuscated >> by the magnitude of the current problem will be stripped away to view >> and we'll probably have some new thoughts to add, then. For now, I >> can't see any of that so this is exactly what I'm looking for. >> >> It goes in incremental steps. Like life. >> >> Jon > >Two things: first, separate the life condition from the >functional requirements you present here. That means >you want a circuit that does: >1) Every X minutes, mute the device >2) Un-mute it when the volume control is fiddled Yup. >That is the only functional requirement set we (responders) >should address. We are not capable of knowing whether it >will address the life situation, and not professionals on >the medical side of things. Obviously. >Second thing: to meet 1 & 2 above one general approach that >might fit is as follows. Put DC and signal on the volume >pot - the wiper will give you a DC voltage as well as the signal. >Use a cap to bring the ac to the amplifying stages, blocking >the DC. Run the DC from the wiper through an R to a small 'lytic >which will charge to the level at the wiper. (A sort of poor man's >sample & hold.) The cap connects to one input of a comparator. >The input goes to the wiper through an identical R with no cap. >Use enough hysteresis to accomodate slight difference in the DC >applied to the inputs. The output of the comparator resets the >ten minute timer. The timer gates the audio out to the speakers. > >I see plenty of possible downside to the above - it requires >"surgery" to each device, which may make it a non-starter. It >also operates for only one direction of the volume control, and >it is only conceptual - you would have to flesh it out. But it >is one idea you could experiment with, and the power source >is already inside the equipment. Let me rephrase this and expose my ignorance. I'm not sure where a volume control intercedes in an audio amplifier system, but if I had to guess then I'd probably imagine it placed it as a divider on the output load of some early stage of the amplifier chain -- mostly because it's probably better located where there is less power to worry about (read: cheaper pot.) The DC offset added to the audio at this point will be 'somewhere.' Changing the pot will move this bias point and you want me to use averaging (RC) to "sample and hold" this set point (actually, after some number of taus have passed, it will have settled on that point -- a reasonable approach for a manual control.) Then use a comparator to compare this against an unfiltered version (instantaneous set point.) I may get lucky and have a pot that has one end at ground or some volt source. Or all three nodes may not be tied to a v-source. If I got it, one immediate issue is that I want _any change_. That's up-volume or down-volume. You mention 'hysteresis' in your suggestion but not for this purpose, as I gather it, but instead as a way of avoiding noisy false tripping due to barely noticeable jarring of the unit, electrical noise, etc. I'd like to detect manual volume changes in either direction. But that is solvable. Do I get the gist so far? Another issue is what mutes the output. If I actively mute, that act itself will affect what those same nodes do for the comparator inputs (filtered and unfiltered) since those nodes must be involved in the muting, itself. That presents a possible problem. What I may like to do is separate things so that I isolate the pot and 'copy' its value to the prior nodes being controlled. Well, that gives me some thought lines to move along. Possible variations are discrete circuits, IC circuits, and a host of topologies to ferret out and design around. Maybe the best way to start is to just start. I'll open up one of the devices and see what I see there. Jon |