Maker Pro
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retrofitting an auto-mute volume control?

J

Jon Kirwan

Jan 1, 1970
0
100 hours per change would get old, fast. Call it 8-10 per month?
okay. If it really saves her just once...

Still have to figure out what to process and how.


I think Vladimir (I love practicing the proper Russian pronunciation
of that name!) pointed out an excellent option (which I've purchased,
but haven't seen yet) that the TI MSP430 is inside of -- it's a watch
that includes 3-axis accelerometer (if I remember what I read
correctly) and RF capability and I already have all the needed
development tools and know how to use them.

It's possible it will work out.

Probably will need to do a 'shrink' on it, though. It's too big as it
is. Much too big. She won't wear it for long. But I'm going to try
it out, anyway. Still looking for auto-mute ideas, though. This
isn't an either-or situation.

Jon
 
E

ehsjr

Jan 1, 1970
0
Jon said:
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
 
J

Jon Kirwan

Jan 1, 1970
0
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
 
J

Jon Kirwan

Jan 1, 1970
0
Photocell power?
Yes, but I was actually thinking about sampling hundreds of times per second.
I dunno how much power, as a alternative to an accelerometer a movable magnet
in a coil (remember the old magnetic phone cartridges) could be used
as a zero power consuming vibration detector.
This is what I thought after writing that posting, and a night sleep:

OK, this is how *I* would proceed,
that is not how you or anyone else should proceed, but how
I would proceed based on what I know and have done in the past.

I would start with making some bracelet or belt with a 3 axis
acceleration sensor.

As Vladimir suggested, by the way. The eZ430-Chronos includes a 96-
seg LCD display, pressure sensor, 3-axis accelerometer and wireless
comms ... cheaply, too. See:
http://focus.ti.com/docs/toolsw/folders/print/ez430-chronos.html?DCMP=Chronos&HQS=Other+OT+chronos
http://focus.ti.com/graphics/tool/ez430-chronos_800.jpg
The sensor would be sampled by a small PIC with ADC, and I would compose a SDLC or HDLC packet.
That is to say a sync byte, some data bytes, and CRC.
This I would connect to one of those 430 MHz (free band) transmitters.

The above is offered with any of: 433 MHz, 868 MHz, or 915 MHz.
Those are the size of a dime, I have one here to remote control the lights.
The range of those is maybe 10 meters or less.
In the same room I would have a receiver for that.
Cable from that receiver to the PC elsewhere.
Digital data stream, twisted cable, perhaps optical.
In the PC a card with a 8035 SCC or similar, to decode the packets.
Hang on a huge harddisk, construct a data format, few bytes,
say n samples per second, some bytes (x, y, z, i, t), where 'i' can hold some extra data,
markers, what not. time stamp.

I've got one of the above on order, some days ago. Before Vladimir
mentioned it, in fact.

I still will have the great difficulty getting her to wear it. Given
past experience, it may take months (probably years) to get her to
cooperate. But I might get lucky.
Then I would just let it run, recording data 24/7, and mark the times when there are seizures.
The advantage is that you do not have to bother the person, you can do any further testing and development
on the PC in non-real time.
What you MUST do however is mark the times that each seizure occurs.
Then, after collecting some real data, have a look at the data,
maybe do a FFT to look for any specific vibrations that may precede or indicate a seizure.
Then it is perhaps just a case of counting times between pulses..

If all else fails, set up a simple neural net, there are many, at least for Linux,
neural net programs available for free.
Some net topology, and run the data through it together with the signals when the seizure really happened.
The net will learn what you yourself have learned, maybe even better and 100% attentive.
From that, over time, you can get a reliable system, by having the PC alert you.

If it works , and why not, you can market it and make a buck or 2 too.

Well, we've been discussing almost these thoughts earlier in this
thread. I've already sat down to think through some ideas about
processing methods. It's an option I will _also_ follow up on (should
she allow me to do so, of course.)

I'm not particularly partial to neural nets. I won't go into details
here, but they are a narrow tool for a narrow range of jobs in my
opinion. There might be something new, but years ago I was decidedly
unimpressed except in a very few cases. Regarding FFT, that is an
obvious step for early post-analysis. For implementation, though, I
may consider cross-correlation against known 'signatures' if I can
develop a set of those. That's easy to understand and can work well,
at times. At the lowest levels of data conditioning, I've a lot of
learning to do about 3-axis accelerometers and their noise and
distribution shape, biases, and other features so that I can make some
sense out of what I read from them. I may consider Kalman filtering.

In short, this won't be a quick fix. Nor the only one, even if it
succeeds to achieve something. One of the nice things about the
concept is that it may provide an hour's notice.

And yes, I intend to discuss some details of such a device with a
neurologist and endocrinologist in February. They may inform me of
other products that already exist (though for some reason they've not
yet done so) and may be willing to support anything I find in the
process over the next year or two. Each individual is different and
adaptation may be easy or hard -- I just don't know. But it is
possible there is a product here. No idea, for now. If so, it's
going to take a team or two and some serious time to get there.

In the meantime, I still plan on working through the auto-mute. More
near term and supplements well anything else I do, regardless.

Jon
 
J

Jon Kirwan

Jan 1, 1970
0
Jon said:
<snip>
Do I get the gist so far?

Yes, I think you understand it. The hysteresis does what you said, but
it was more to make the trigger "window" a little wider, and make the
switching crisp and definite. As far as moving the control in either
direction, it is solvable as you said. Maybe use a second comparator
set up to switch when the control moves in the other direction. As
far as muting, use the comparator output(s) to reset the timer, and
the timer output to switch the audio output line from the speaker(s)
to a resistor or resistors and vice versa.

Regarding the existing pot setup, it is often like this,
where the signal comes from the preamp:
Signal---[cap]---+
|
P
O<---- signal out to amplifier stage
T
|
Gnd -------------+

Yes. I anticipate this _after_ the first stage's conditioning of the
input and well before the final power stage.

Suppose that the 'signal out' you mention passes through yet another
cap before the next stage. If so, isn't this a problem for a DC path?

|| C1
IN --------||-----,
|| |
|
\
Rx / ||
\ <----||----- OUT
/ || C2
\
|
|
---
///

No DC current path, right?

In any case, I just opened up my first victim. The pot has 7 points
of attachment into the PC board. Two of them are twist tabs for the
main mounting and are themselves grounded. Of the other five, they
are on 5-hole line tangent at the circumference. One of these is tied
to the same ground. But the other four 'go somewhere'.

Call the pins A, B, C, D, and E. Pin B is tied to the negative rail
(ground.) (Since there is a battery system, as well as AC, I can
verify that it is the most negative rail by using the most negative
side of the battery pack connection.)

Here are the measurements against ground for two rotation positions:

MIN VOL MAX VOL
---------------------------
A 0.5 ohm 32.3k ohm
B --- ---
C 0.5 ohm 32.3k ohm
D 220 ohm 32.3k ohm
E 47.7k ohm 32.3k ohm

Obviously, in-circuit and not desoldered. Interestingly, the
resistance between A and C goes from about 0 ohms to about 64.5k ohms
going from MIN to MAX volume, respectively. The resistance from C to
D goes from 220 ohms to 0 ohms going from MIN to MAX, respectively.

That's enough to make this interesting. I need to think more closely
to be sure, but the pot appears to not be a single resistor track and
wiper, at first blush.

I think I need to assume every other system will be just as messy.
Then, at least, the only way is down -- easier -- from there.
It should't affect the comparators if it occurs between the final
amplifier and the speaker(s).

I have a hard time imagining a pot right at the final stage, because
of the power (few watts, at least) involved. But you might be talking
about something else I said.
Good luck!

Thanks. Looks like I'm going to need it. Blasted thing.

Jon
 
E

ehsjr

Jan 1, 1970
0
Jon said:
Jon said:
<snip>
Do I get the gist so far?

Yes, I think you understand it. The hysteresis does what you said, but
it was more to make the trigger "window" a little wider, and make the
switching crisp and definite. As far as moving the control in either
direction, it is solvable as you said. Maybe use a second comparator
set up to switch when the control moves in the other direction. As
far as muting, use the comparator output(s) to reset the timer, and
the timer output to switch the audio output line from the speaker(s)
to a resistor or resistors and vice versa.

Regarding the existing pot setup, it is often like this,
where the signal comes from the preamp:
Signal---[cap]---+
|
P
O<---- signal out to amplifier stage
T
|
Gnd -------------+


Yes. I anticipate this _after_ the first stage's conditioning of the
input and well before the final power stage.

Suppose that the 'signal out' you mention passes through yet another
cap before the next stage. If so, isn't this a problem for a DC path?

|| C1
IN --------||-----,
|| |
|
\
Rx / ||
\ <----||----- OUT
/ || C2
\
|
|
---
///

No DC current path, right?

In any case, I just opened up my first victim. The pot has 7 points
of attachment into the PC board. Two of them are twist tabs for the
main mounting and are themselves grounded. Of the other five, they
are on 5-hole line tangent at the circumference. One of these is tied
to the same ground. But the other four 'go somewhere'.

Call the pins A, B, C, D, and E. Pin B is tied to the negative rail
(ground.) (Since there is a battery system, as well as AC, I can
verify that it is the most negative rail by using the most negative
side of the battery pack connection.)

Here are the measurements against ground for two rotation positions:

MIN VOL MAX VOL
---------------------------
A 0.5 ohm 32.3k ohm
B --- ---
C 0.5 ohm 32.3k ohm
D 220 ohm 32.3k ohm
E 47.7k ohm 32.3k ohm

Obviously, in-circuit and not desoldered. Interestingly, the
resistance between A and C goes from about 0 ohms to about 64.5k ohms
going from MIN to MAX volume, respectively. The resistance from C to
D goes from 220 ohms to 0 ohms going from MIN to MAX, respectively.

That's enough to make this interesting. I need to think more closely
to be sure, but the pot appears to not be a single resistor track and
wiper, at first blush.

I think I need to assume every other system will be just as messy.
Then, at least, the only way is down -- easier -- from there.

It should't affect the comparators if it occurs between the final
amplifier and the speaker(s).


I have a hard time imagining a pot right at the final stage, because
of the power (few watts, at least) involved. But you might be talking
about something else I said.

Good luck!


Thanks. Looks like I'm going to need it. Blasted thing.

Jon

Hi Jon,

Usually the pot is early in the audio chain, between the
preamp and the power amp stage, something like this:

input===>preamp===>pot===ground
|
+===>power amp======>speaker



Regarding the following:
|| C1
IN --------||-----,
|| |
|
\
Rx / ||
\ <----||----- OUT
/ || C2
\
|
|

Correct, and that is what you need. The caps keep the DC for
the automute out of the audio circuitry. You need to apply DC to
the top of the pot, and take DC off the wiper prior to the cap.
If the DC for the auto-mute circuit is completely isolated from
the supply for the device, ie, no common ground, no common +,
then there's no need to worry about the AC signal being attenuated
by finding a path through the DC supply circuit. If it is not
isolated, then it becomes a try it and see, with possible
difficulty setting a DC level at the top of the pot that works.

If you can't isolate, then there is another possible approach.
You could apply narrow DC pulses to the top of the pot - too
narrow for the audio to be affected. For example, say the pulse
was 5 or 10 microseconds long, once every 50 miliseconds.
The audio from the speaker should be unaffected even with a common
power supply, yet a train of digital pulses would be available at
the wiper. A difference in pulse amplitude would indicate that the
pot has been moved. Get the pulses at the wiper, and adc to
establish a level in a register in a micro. The micro can compare
saved_level to current_level and if the delta is equal to or greater
than a target, reset the timer. Wouldn't matter if the pot was
moved up or down as the micro only cares about the delta between
the new reading and the old reading.

You still need to be able to find the right connection points
to the pot, whatever you try. It's probably worth trying to get
schematics for all of the gear you might want to automute.
If you can get at least some schematics, it'll save you some
work and head scratching.

Ed
 
J

Jon Kirwan

Jan 1, 1970
0
Jon said:
Jon Kirwan wrote:

<snip>
Do I get the gist so far?

Yes, I think you understand it. The hysteresis does what you said, but
it was more to make the trigger "window" a little wider, and make the
switching crisp and definite. As far as moving the control in either
direction, it is solvable as you said. Maybe use a second comparator
set up to switch when the control moves in the other direction. As
far as muting, use the comparator output(s) to reset the timer, and
the timer output to switch the audio output line from the speaker(s)
to a resistor or resistors and vice versa.

Regarding the existing pot setup, it is often like this,
where the signal comes from the preamp:
Signal---[cap]---+
|
P
O<---- signal out to amplifier stage
T
|
Gnd -------------+


Yes. I anticipate this _after_ the first stage's conditioning of the
input and well before the final power stage.

Suppose that the 'signal out' you mention passes through yet another
cap before the next stage. If so, isn't this a problem for a DC path?

|| C1
IN --------||-----,
|| |
|
\
Rx / ||
\ <----||----- OUT
/ || C2
\
|
|
---
///

No DC current path, right?

In any case, I just opened up my first victim. The pot has 7 points
of attachment into the PC board. Two of them are twist tabs for the
main mounting and are themselves grounded. Of the other five, they
are on 5-hole line tangent at the circumference. One of these is tied
to the same ground. But the other four 'go somewhere'.

Call the pins A, B, C, D, and E. Pin B is tied to the negative rail
(ground.) (Since there is a battery system, as well as AC, I can
verify that it is the most negative rail by using the most negative
side of the battery pack connection.)

Here are the measurements against ground for two rotation positions:

MIN VOL MAX VOL
---------------------------
A 0.5 ohm 32.3k ohm
B --- ---
C 0.5 ohm 32.3k ohm
D 220 ohm 32.3k ohm
E 47.7k ohm 32.3k ohm

Obviously, in-circuit and not desoldered. Interestingly, the
resistance between A and C goes from about 0 ohms to about 64.5k ohms
going from MIN to MAX volume, respectively. The resistance from C to
D goes from 220 ohms to 0 ohms going from MIN to MAX, respectively.

That's enough to make this interesting. I need to think more closely
to be sure, but the pot appears to not be a single resistor track and
wiper, at first blush.

I think I need to assume every other system will be just as messy.
Then, at least, the only way is down -- easier -- from there.

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.

It should't affect the comparators if it occurs between the final
amplifier and the speaker(s).


I have a hard time imagining a pot right at the final stage, because
of the power (few watts, at least) involved. But you might be talking
about something else I said.

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.

Good luck!


Thanks. Looks like I'm going to need it. Blasted thing.

Jon

Hi Jon,

Usually the pot is early in the audio chain, between the
preamp and the power amp stage, something like this:

input===>preamp===>pot===ground
|
+===>power amp======>speaker



Regarding the following:
|| C1
IN --------||-----,
|| |
|
\
Rx / ||
\ <----||----- OUT
/ || C2
\
|
|

Correct, and that is what you need. The caps keep the DC for
the automute out of the audio circuitry. You need to apply DC to
the top of the pot, and take DC off the wiper prior to the cap.

yes. I had drawn that modification in a schematic I was going to post
and then just removed it because I figured calling attention to it
would be enough and I hoped you'd say what I see you saying above.
Because it makes complete sense to me (and I was able to figure it out
on my own, which is a good thing.)
If the DC for the auto-mute circuit is completely isolated from
the supply for the device, ie, no common ground, no common +,
then there's no need to worry about the AC signal being attenuated
by finding a path through the DC supply circuit. If it is not
isolated, then it becomes a try it and see, with possible
difficulty setting a DC level at the top of the pot that works.

Got it.
If you can't isolate, then there is another possible approach.
You could apply narrow DC pulses to the top of the pot - too
narrow for the audio to be affected. For example, say the pulse
was 5 or 10 microseconds long, once every 50 miliseconds.
The audio from the speaker should be unaffected even with a common
power supply, yet a train of digital pulses would be available at
the wiper. A difference in pulse amplitude would indicate that the
pot has been moved. Get the pulses at the wiper, and adc to
establish a level in a register in a micro. The micro can compare
saved_level to current_level and if the delta is equal to or greater
than a target, reset the timer. Wouldn't matter if the pot was
moved up or down as the micro only cares about the delta between
the new reading and the old reading.

Understood. That I can do, as well.
You still need to be able to find the right connection points
to the pot, whatever you try. It's probably worth trying to get
schematics for all of the gear you might want to automute.
If you can get at least some schematics, it'll save you some
work and head scratching.

Yeah. So there is the pain. Finding that damned schematics for each
case.

I had early posted the "wish" that this would be applied right at the
speaker itself and drew its power from speaker drive power itself. The
pair of speaker wires is pretty much universal. Of course, that's a
whole other bag of worms. But after looking at this single unit, I'm
wondering if it might be worth thinking a little more about.

Or just build my own amplifier system, for gosh sake! Then I _know_
what I'm doing and can make it work properly without all the hassle.
Of course, I'll need a 'pick-off' point for the existing boxes and
devices. Which _could_ be the speakers, though that isn't the usual
point -- if I conditioned that before applying it to the amplifier
chain.

Now why can't manufacturers just realize that an auto-mute function
would be handy! I'd buy that.

Okay. That seems like the right direction even though it adds an
external box that makes this more complex for her and us and takes up
more space and adds yet another 'wire system' to trip over or break
when she drags things around. Screw the auto-mute built into the
boxes. I'll just work on the amplifier design (or select an easily
modifiable system that includes case and power.)

Jon
 
E

ehsjr

Jan 1, 1970
0
Jon said:
Jon said:
On Sun, 13 Dec 2009 22:47:39 -0500, ehsjr wrote:



Jon Kirwan wrote:


<snip>
Do I get the gist so far?

Yes, I think you understand it. The hysteresis does what you said, but
it was more to make the trigger "window" a little wider, and make the
switching crisp and definite. As far as moving the control in either
direction, it is solvable as you said. Maybe use a second comparator
set up to switch when the control moves in the other direction. As
far as muting, use the comparator output(s) to reset the timer, and
the timer output to switch the audio output line from the speaker(s)
to a resistor or resistors and vice versa.

Regarding the existing pot setup, it is often like this,
where the signal comes from the preamp:
Signal---[cap]---+
|
P
O<---- signal out to amplifier stage
T
|
Gnd -------------+


Yes. I anticipate this _after_ the first stage's conditioning of the
input and well before the final power stage.

Suppose that the 'signal out' you mention passes through yet another
cap before the next stage. If so, isn't this a problem for a DC path?

|| C1
IN --------||-----,
|| |
|
\
Rx / ||
\ <----||----- OUT
/ || C2
\
|
|
---
///

No DC current path, right?

In any case, I just opened up my first victim. The pot has 7 points
of attachment into the PC board. Two of them are twist tabs for the
main mounting and are themselves grounded. Of the other five, they
are on 5-hole line tangent at the circumference. One of these is tied
to the same ground. But the other four 'go somewhere'.

Call the pins A, B, C, D, and E. Pin B is tied to the negative rail
(ground.) (Since there is a battery system, as well as AC, I can
verify that it is the most negative rail by using the most negative
side of the battery pack connection.)

Here are the measurements against ground for two rotation positions:

MIN VOL MAX VOL
---------------------------
A 0.5 ohm 32.3k ohm
B --- ---
C 0.5 ohm 32.3k ohm
D 220 ohm 32.3k ohm
E 47.7k ohm 32.3k ohm

Obviously, in-circuit and not desoldered. Interestingly, the
resistance between A and C goes from about 0 ohms to about 64.5k ohms
going from MIN to MAX volume, respectively. The resistance from C to
D goes from 220 ohms to 0 ohms going from MIN to MAX, respectively.

That's enough to make this interesting. I need to think more closely
to be sure, but the pot appears to not be a single resistor track and
wiper, at first blush.

I think I need to assume every other system will be just as messy.
Then, at least, the only way is down -- easier -- from there.



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.

It should't affect the comparators if it occurs between the final
amplifier and the speaker(s).


I have a hard time imagining a pot right at the final stage, because
of the power (few watts, at least) involved. But you might be talking
about something else I said.



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.

Good luck!


Thanks. Looks like I'm going to need it. Blasted thing.

Jon

Hi Jon,

Usually the pot is early in the audio chain, between the
preamp and the power amp stage, something like this:

input===>preamp===>pot===ground
|
+===>power amp======>speaker



Regarding the following:
|| C1
IN --------||-----,
|| |
|
\
Rx / ||
\ <----||----- OUT
/ || C2
\
|
|

Correct, and that is what you need. The caps keep the DC for
the automute out of the audio circuitry. You need to apply DC to
the top of the pot, and take DC off the wiper prior to the cap.


yes. I had drawn that modification in a schematic I was going to post
and then just removed it because I figured calling attention to it
would be enough and I hoped you'd say what I see you saying above.
Because it makes complete sense to me (and I was able to figure it out
on my own, which is a good thing.)

If the DC for the auto-mute circuit is completely isolated from
the supply for the device, ie, no common ground, no common +,
then there's no need to worry about the AC signal being attenuated
by finding a path through the DC supply circuit. If it is not
isolated, then it becomes a try it and see, with possible
difficulty setting a DC level at the top of the pot that works.


Got it.

If you can't isolate, then there is another possible approach.
You could apply narrow DC pulses to the top of the pot - too
narrow for the audio to be affected. For example, say the pulse
was 5 or 10 microseconds long, once every 50 miliseconds.
The audio from the speaker should be unaffected even with a common
power supply, yet a train of digital pulses would be available at
the wiper. A difference in pulse amplitude would indicate that the
pot has been moved. Get the pulses at the wiper, and adc to
establish a level in a register in a micro. The micro can compare
saved_level to current_level and if the delta is equal to or greater
than a target, reset the timer. Wouldn't matter if the pot was
moved up or down as the micro only cares about the delta between
the new reading and the old reading.


Understood. That I can do, as well.

You still need to be able to find the right connection points
to the pot, whatever you try. It's probably worth trying to get
schematics for all of the gear you might want to automute.
If you can get at least some schematics, it'll save you some
work and head scratching.


Yeah. So there is the pain. Finding that damned schematics for each
case.

I had early posted the "wish" that this would be applied right at the
speaker itself and drew its power from speaker drive power itself. The
pair of speaker wires is pretty much universal. Of course, that's a
whole other bag of worms. But after looking at this single unit, I'm
wondering if it might be worth thinking a little more about.

Or just build my own amplifier system, for gosh sake! Then I _know_
what I'm doing and can make it work properly without all the hassle.
Of course, I'll need a 'pick-off' point for the existing boxes and
devices. Which _could_ be the speakers, though that isn't the usual
point -- if I conditioned that before applying it to the amplifier
chain.

Now why can't manufacturers just realize that an auto-mute function
would be handy! I'd buy that.

Okay. That seems like the right direction even though it adds an
external box that makes this more complex for her and us and takes up
more space and adds yet another 'wire system' to trip over or break
when she drags things around. Screw the auto-mute built into the
boxes. I'll just work on the amplifier design (or select an easily
modifiable system that includes case and power.)

Jon

Well, you could do it at the existing speaker(s) with an active
rectifier to develop a DC level, but I can't figure out how to
make it reliable, because audio level constantly changes
without moving the volume control. So your idea of building
an amp with automuting sounds best.

One other possibility, which depends on your life situation
knowledge. A ten minute (or whatever) timer mutes the speaker
AND turns on a mic & amp VOX circuit. The mic circuit would be
off during the 10 minute period so that it won't detect sound
from the equipment when it is not muted. If that circuit detects
noise from her normal activity, it resets the timer and un-mutes.
The noise from her normal activity is the key - if her activity
to go to the equipment & turn the volume control can be detected
that approach might work.

Ed
 
J

Jon Kirwan

Jan 1, 1970
0
<snip>
Well, you could do it at the existing speaker(s) with an active
rectifier to develop a DC level, but I can't figure out how to
make it reliable, because audio level constantly changes
without moving the volume control. So your idea of building
an amp with automuting sounds best.

There is plenty of power when the volume is UP, which is when I most
need muting after a delay. Other times it would work if it could
stand out of the way and not mute, I suppose. Best is to have a
consistent muting behavior, though. Higher power outputs (and we have
some that are blasting away at 20-30 watts, maybe) mean fairly high
drive voltages and passing and blocking those may not be
straight-forward. In any case, deriving power for the circuit from
the speaker output power only makes the whole thing seem even more
outside my skills.

I think most of the stuff I have either has a headphone jack or else a
line out (or both.) The line out wouldn't disable output, while the
headphone jack usually does. Their signal levels and drive impedances
are different, so each would need a slightly different 1st stage --
but I could arrange an either-or circuit for that (after I figure out
what the signals are like.) The rest isn't hard and I don't need high
fidelity or high power outputs. This doesn't have to be a 30-watt
plastic tiger. A quasi-complimentary output and perhaps a diff-amp
pair before it seems all that is necessary. I _do_ need to spend some
time figuring out what phone jack and line outputs look like though. I
am ignorant, there.
One other possibility, which depends on your life situation
knowledge. A ten minute (or whatever) timer mutes the speaker
AND turns on a mic & amp VOX circuit. The mic circuit would be
off during the 10 minute period so that it won't detect sound
from the equipment when it is not muted. If that circuit detects
noise from her normal activity, it resets the timer and un-mutes.
The noise from her normal activity is the key - if her activity
to go to the equipment & turn the volume control can be detected
that approach might work.

You are making me like the homebrew amplifier even more. ;)

Jon
 
J

JosephKK

Jan 1, 1970
0
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

For bog simple muting and low energy consumption consider latching relays:
maybe like this of even in a to99 can.

http://www.futurlec.com/Datasheet/Relays/HFD2.pdf

And whenever possible, switch at signal levels.
 
J

JosephKK

Jan 1, 1970
0
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

Myodetection might be possible. But it is a contact sensor and may be
found unsuitable for that reason.
 
J

JosephKK

Jan 1, 1970
0
Probably will need to do a 'shrink' on it, though. It's too big as it
is. Much too big. She won't wear it for long. But I'm going to try
it out, anyway. Still looking for auto-mute ideas, though. This
isn't an either-or situation.

Jon

It does not necessarily have to be a watch, it could be a necklace or a tiara.
 
J

JosephKK

Jan 1, 1970
0
Jon said:
<snip>
Do I get the gist so far?

Yes, I think you understand it. The hysteresis does what you said, but
it was more to make the trigger "window" a little wider, and make the
switching crisp and definite. As far as moving the control in either
direction, it is solvable as you said. Maybe use a second comparator
set up to switch when the control moves in the other direction. As
far as muting, use the comparator output(s) to reset the timer, and
the timer output to switch the audio output line from the speaker(s)
to a resistor or resistors and vice versa.

Regarding the existing pot setup, it is often like this,
where the signal comes from the preamp:
Signal---[cap]---+
|
P
O<---- signal out to amplifier stage
T
|
Gnd -------------+

Yes. I anticipate this _after_ the first stage's conditioning of the
input and well before the final power stage.

Suppose that the 'signal out' you mention passes through yet another
cap before the next stage. If so, isn't this a problem for a DC path?

|| C1
IN --------||-----,
|| |
|
\
Rx / ||
\ <----||----- OUT
/ || C2
\
|
|
---
///

No DC current path, right?

In any case, I just opened up my first victim. The pot has 7 points
of attachment into the PC board. Two of them are twist tabs for the
main mounting and are themselves grounded. Of the other five, they
are on 5-hole line tangent at the circumference. One of these is tied
to the same ground. But the other four 'go somewhere'.

This sounds like a very standard audio (log) taper dual element stereo
volume control. Most of the ones i have seen the physical elements are
stacked along the axis of the shaft.
Call the pins A, B, C, D, and E. Pin B is tied to the negative rail
(ground.) (Since there is a battery system, as well as AC, I can
verify that it is the most negative rail by using the most negative
side of the battery pack connection.)

Here are the measurements against ground for two rotation positions:

MIN VOL MAX VOL
---------------------------
A 0.5 ohm 32.3k ohm
B --- ---
C 0.5 ohm 32.3k ohm
D 220 ohm 32.3k ohm
E 47.7k ohm 32.3k ohm

Obviously, in-circuit and not desoldered. Interestingly, the
resistance between A and C goes from about 0 ohms to about 64.5k ohms
going from MIN to MAX volume, respectively. The resistance from C to
D goes from 220 ohms to 0 ohms going from MIN to MAX, respectively.

Sounds like A and C are the "wipers" (output side). D and E are acting
strange though. Take measurements at half rotation as well. It should
help sort things
 
J

Jon Kirwan

Jan 1, 1970
0
It does not necessarily have to be a watch, it could be a necklace or
a tiara.

She loves watches and takes mine off and puts it back on, a lot. I've
even seen her 'try' to consider the idea of putting it on her own arm.
But only for a moment.

It took us many, many years just to get her to wear a t-shirt. As I
think I already mentioned, she is very 'sensitive' to stuff that
touches her. Most types of cloth are impossible and we have to
carefully select textures and other factors. She still won't wear
anything more than a long t-shirt and underpants, except in
contained/controlled situations (such as driving in the car.)

A necklace or tiara is not probably not happening. But every idea may
be worth a try.

Jon
 
J

JosephKK

Jan 1, 1970
0
She loves watches and takes mine off and puts it back on, a lot. I've
even seen her 'try' to consider the idea of putting it on her own arm.
But only for a moment.

It took us many, many years just to get her to wear a t-shirt. As I
think I already mentioned, she is very 'sensitive' to stuff that
touches her. Most types of cloth are impossible and we have to
carefully select textures and other factors. She still won't wear
anything more than a long t-shirt and underpants, except in
contained/controlled situations (such as driving in the car.)

A necklace or tiara is not probably not happening. But every idea may
be worth a try.

Jon

Very challenging indeed. Even trying that she is "a princess" only
while wearing the gizmo (or one or more of several?) may not work.
 
J

Jon Kirwan

Jan 1, 1970
0
Basically it is the electric potentials that can be measured in
correlation of muscle contraction. It is a well known interference
for ElectroEncephalaGrams (EEG).

Not much quality stuff on a quick Internet search:

http://openprosthetics.org/myoelectric

http://ieeexplore.ieee.org/Xplore/l...l5/10755/33900/01616206.pdf&authDecision=-203

I'll keep this topic in mind and discuss it with a neurologist and
endocrinologist early next year (Feb.) I'm trying to get a project
started with them and a few researchers up at UofW, anyway, on a
different topic related to nano-encapsulation. So this sounds like
something they can either inform me a little about or else refer me to
someone they know who can do better. Sounds like something I'm not
going to have an answer about right away, but might pay off to learn
about at least. Thanks for the term. I'll run with it.

Jon
 
J

Jon Kirwan

Jan 1, 1970
0
Very challenging indeed. Even trying that she is "a princess" only
while wearing the gizmo (or one or more of several?) may not work.

She wouldn't understand the concept... at least, not right away. She
does 'get things,' though. We never know what she wants to spend time
on until she shows us, so we continually supply different things to
see what catches. There are some movies she seemed to like -- Roger
Rabbit, for example. But often for movies, at first, it seems more
about sounds and music and perhaps some basic actions. But after
watching some movies maybe 50 or 100 times, she will start laughing at
the right places or changing moods where others might, which tells me
that over time the broad strokes in the movie begin to come across
almost like they do with many 'normal' folks and she understands a lot
more. But some things may take years. "A princess" feeling is
something I suspect would take a very long time to instill.

Something I haven't mentioned is that in all her 25 years she has
never reacted to physical pain -- severe or otherwise -- by crying or
crying out like many will. She has accidentally pressed up on a
searing hot piece of metal and sustained 3rd degree burns without us
knowing, right away. She laughed and did things like always, the only
difference we noticed being that she seemed to react a little more
negatively to abrupt sounds, like a phone. Now, she has always
freaked out with a phone ringing or a dog barking and so on. Noises
that most of us accommodate, often even losing notice to us like that
of a closing door, will send her reeling and freaking out. That is,
if those sounds aren't under her control. But we can tell when she is
a little _more_ like that than other times. And in this case, we
noticed and started looking more closely at her for physical injury.
Sure enough, there it was. She sees no reason to cry, no purpose --
she knows it doesn't change the pain and she doesn't understand that
sometimes we can help. So she just grins and bears it. Very much, I
imagine, as a great many creatures do in the wild. (A cat will often
get an abscess that "blows out" their cheekside. But they don't
complain, don't cry, don't moan. They move on. She is very much like
that.

When she broke her radius and ulna in one grand mal seizure a year ago
last October, and I discovered it as I helped her through the seizure,
she woke up from the seizure that time quite quickly. But while I was
totally screaming to my wife to find a 90-degree angled piece of
Styrofoam in which to rest her broken arm, and going nuts trying to
keep her from moving it in the meantime to mitigate muscle and tissue
damage from grinding against the broken sharded ends of bone, she was
just curious. She looked at her arm, tried to use it, found it odd,
but never for a second showed the slightest signs of a grimace or
crying or anything. Curiosity, almost. I got her packed up, taped,
dressed and started taking her into the car to bring her to the
closest emergency center 5-minutes away, and as she tried to use that
arm to help me close the car door.

Now, I _know_ for a fact she feels pain and feels worse pain more.
That comes from other observations. But she does NOT react to it,
even of the most painful variety, except with an almost stoicism and a
remarkable clarity of thinking about it. It's one of those things I
keep marveling about, trying to grasp it more fully. It's a stand out
thing about her.

She also _cares_ a great deal, about animals and people and things. If
anything is damaged or fails to work, she brings it to me to fix. If
an animal is hurt, she tries to get me to deal with it. If one of us
is hurt, she carefully watches and will be far more sensitive to us
than otherwise she might be.

Regarding the noises that disturb her and the fact that I earlier
mentioned (or hinted) that ones she makes don't disturb her (as much,
anyway), it's like that in all of us. Just very much heightened in
her. For example, consider the idea of someone coming up behind you
with a firecracker and setting it off without you knowing it. Your
reaction is sudden and quite often filled first with fear and then
quickly after with anger. Not everyone's reaction will be exactly the
same and we do "learn" and "adapt" -- especially if this happens a lot
to us. But if you aren't pre-conditioned, that event includes
frustration, possible fear, and quite likely anger -- with anger
perhaps taking a second or two to arrive in clear form. Now consider
the idea that someone tells you first and instead of setting it off in
back of you, they do it in front of you where you can see the fuse
dwindle down. Let's say, same distances to your ears either way. In
this case, you can mentally 'steel' yourself and the impact is far far
less. We are able to "prepare" ourselves, and this preparation no
doubt in my mind involves physical changes that our brain initiates in
anticipation which helps to mitigate the event's necessary chain of
triggers within our bodies... perhaps with the early release of COMT
and MAO, though I'm not sure about exactly what mechanisms are in
play. I just know they work.

She's like that, too. If she is the reason or cause, she is much
better able to handle it. But if the sound is not in her control -- I
close the door, she doesn't, for example -- then her reaction is
strong... very strong.

On a more mundane note, we do this all the time with the closing of
doors. When a door closes behind us, the sounds reach our cochlea and
almost immediately, at a very low level, signals to the pituitary
gland to trigger an adrenaline (epinephrine) release. This is
measurable, by the way. Shortly later, higher functioning levels in
the brain associate the sudden sound with a door closing and another
signal arrives, triggering the release of digestive enzymes like COMT
and MAO. Although there is a measurable pulse and decay, we learn to
completely ignore the visceral responses over time. Yet they remain,
while many of us almost completely subsume the event into near
unconsciousness unless it is a particularly remarkable closing of a
door.

Now imagine that she does NOT have this follow-on mechanism -- some
part of it is broken. Every time I say something, it is a series of
sounds... rata-tata-rata-da-da-da... that reach her ears and perhaps
trigger epinephrine releases. Every time a phone rings... Every time
a door closes... every time something sound-wise takes place that has
a rapid attack (in the attack-decay sense) to it, she gets "hit" with
adrenaline. But she has no mechanism for COMT/MAO enzyme triggers, so
the decay is much, much slower to leave. And she is in a heightened
state of anxiety that doesn't readily leave, so new "impacts" add and
add.

It's a lot like that, I think.

Jon
 
J

Jon Kirwan

Jan 1, 1970
0
<snip>
Now, I _know_ for a fact she feels pain and feels worse pain more.
That comes from other observations. But she does NOT react to it,
even of the most painful variety, except with an almost stoicism and a
remarkable clarity of thinking about it. It's one of those things I
keep marveling about, trying to grasp it more fully. It's a stand out
thing about her.
<snip>

Something I thought to add. I also do not respond to pains as many
others do. Mostly, I think, because my responses are viscerally more
analytical. A story illustrates.

We enjoy all wildlife and spend a lot of time in the woods just
watching or studying animals in their behaviors, talking about what we
observe, theorizing, and just plain loving the experiences. This got
us to a point in our lives where we were doing "animal aid" volunteer
work and for a time my wife and I became the contact point for 911
calls regarding "wild animals." I was responding to a wild raccoon
call in a new housing development near a woods and trapped the _huge_
raccoon against a fence and house corner. I had on motorcycle leather
gloves and had towels with me (very useful) and I managed to engage it
and subdue it. (Raccoons, especially big ones, are very powerful. But
a knee in their back with the weight of a human behind it completely
sprawls them if applied craftily and well.) While wrapping it with
the towels (much like a straight jacket idea), I made a mistake and
allowed it's mouth to grasp my thumb. It's teeth went straight
through the leather glove and deeply enough to fully engage its teeth
right into some of my bones. It was quite painful.

However, I felt _no_ emotion whatsoever. Not immediately, not later.
No anger at the animal, at all. (I never have.. it is something I
simply lack.) I completely understood what it had done and why it had
done it. It was no fault of the raccoon and my mind was _purely_ and
_only_ working on the details I'd need to consider in order to
mitigate damage to me and to finish the job at hand. I had no other
emotions operating. None, at least, that I was aware of.

There have been many other such events in my life like that. We deal
with animals and I'm not immune to injuries -- for example, I'm
missing the tip of my right index finger from a chipper shredder event
some years back and I've run another finger into a running saw (mostly
okay, now.) A long life is not unlike that. But I remember this one
in particular because it was the first time I realized that other
people would likely feel anger towards an animal that attacked them.
And I was in my 30's before it ever dawned on me that anyone could
feel anger for that reason. Getting angry at an animal or inanimate
object when injured seems irrational and illogical to me and makes no
sense, whatsoever. And I certainly do NOT have any visceral (gut)
reactions I know about in that regard. These kinds of things are
simply "problems to solve" to me. Nothing more. Yes, I feel the
pain. And yes I react to it! Just without the confounding emotions
others seem to have.

It was afterwards, talking with others about the raccoon event, that
they tried to empathize with me and talk about "boy, you must have
been very angry." It was only in my own mystery about why they'd say
so and in the ensuring questions I asked them and their own answers
that it slowly began to dawn upon me that others would feel such
emotions towards creatures and objects (like cupboard doors they
bonked into at times.) I still find that a bit of a mystery, because
I can't find it inside myself to understand it in a gut-way.

Now, for me, people are entirely a different thing. I can get quite
upset at people doing terrible things to others, or me. Because I
know they know better. And I believe I can feel very much like others
about that. Visciousness, mean-spiritness, disingenuousness, climbing
on the backs of others, and so on are very human behaviors I do get
angry about and despise. It's just that I know a table or door isn't
viscious and cannot be. Similarly, most animal behaviors as well. So
there is nothing there to get angry at. And anger is a higher level
brain function for me -- it requires analysis to feel. It _never_
occurs to me at a primal-response level, before higher functioning
gets a chance to operate.

Which makes me wonder how much of her responses are like mine.

Jon
 
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