In search of a meter movement

[Black Iccy]

Long time since I've posted on Usenet.
What I want to do is give some public address system
operators (in a hotel actually), a clear and easy
visualisation of just how loud they have got things
running. A VU meter situation.

What they should be able to do is see, from a distance,
a meter which preferably will have a 270 degree travel arm

Small meters just won't cut the mustard. Ideally, too,
I envisage driving the meter from the amp speaker supply
so that's why I'm not employing electronic level display systems.
Trying to keep things as simple as possible.

It occurs to me that what I really should use is something
like a car's tachometer movement. I know modern units have
internal electronics etc. They would be un-necessary and
unusable so I'd be stripping them out.

In general, what are the movements?
Still D'asonval ?
What sort of FS sensitivity - 1 mA FS?
Anyone played with these things?
Thanks.

 

[Jeff Liebermann]

On Mon, 29 Oct 2012 15:07:59 +1100, Black Iccy
<Daedelus@whereamIinvalid.com> wrote:

Long time since I've posted on Usenet.

Contrary to rumors to the contrary, Usenet is alive and well.

What I want to do is give some public address system
operators (in a hotel actually), a clear and easy
visualisation of just how loud they have got things
running. A VU meter situation.

What they should be able to do is see, from a distance,
a meter which preferably will have a 270 degree travel arm

What distance?

Small meters just won't cut the mustard. Ideally, too,
I envisage driving the meter from the amp speaker supply
so that's why I'm not employing electronic level display systems.
Trying to keep things as simple as possible.

I used to deal with theater applause meters in the 1960's. Something
like this, but not quite so big (and ugly):
<http://en.wikipedia.org/wiki/Clap-o-meter>
<http://blog.eastmanhouse.org/wp-content/uploads/2009/09/Clap-o-meter.jpg>
They were huge meters, about 4x6ft large, with an indicator arm that
probably weighted several pounds. The devices didn't use a standard
meter movement. It used a geared motor fighting a spiral spring. The
more power applied to the motor, the more it would compress the spring
and move indicator. The motor would complain, sometimes get hot, but
since the applause was not continuously present, it had time to cool
down.

It occurs to me that what I really should use is something
like a car's tachometer movement. I know modern units have
internal electronics etc. They would be un-necessary and
unusable so I'd be stripping them out.

Most cheap automotive gauges are thermal gauges. That provides
damping and vibration proofing. They're also dirt cheap. Tachometers
that need to move rapidly use a taut band variation on the D'Arsonval
meter. A jeweled bearing D'Arsonval movement wouldn't last a month in
a vehicle.

In general, what are the movements?
Still D'asonval ?

In some places, but not all. D'Arsonval, taut band, thermal
(bimetallic), electrodynamic, moving vane, thermocouple, piezo, etc.
<http://gactaern.org/Unit%20Plan/Transportation/Electrical_Electronic_Systems_Design/ESD_7_Non_Electronic_Guage_Indicators.PPT>

What sort of FS sensitivity - 1 mA FS?

50ua FS for the better meters. Moving mirror galvanometers will to
maybe 5ua full scale.

Anyone played with these things?

Yep. I even got paid to play with them. Maybe if you supplied some
numbers (i.e. distance, size, cost, etc), it might be possible to
offer some sane suggestions?

Ok, enough nonsense. I have two suggestions:

1. Use a virtual meter. Yes, it requires a computah and LCD screen,
but those are quite common and amazingly cheap. You can also do it
with a SBC (single board computer). On the LCD screen is your meter.
The audio goes into the sound card of the computah. If you need a
monster meter, use a projection display. If an LCD screen is big
enough, commandeer a hotel TV set.
<http://www.sermonvideos.com/FileCloseup.html?&ID=26107>
<http://www.theapplausemeter.com>

2. Use a moving mirror. The deflection of the mirror will move a
reflected light beam across the wall or ceiling. The amount of
movement is proportional to the amplitude. The major problem will be
damping the mirror so that it doesn't "ring" or move like sludge.

I doubt if you can find a large enough panel meter to be seen clearly
across a room. I have several pieces of antique test equipment with
maybe 12" meters. That's about as big as they get. The problem is
that the indicator arm is rather thin and light by necessity, and
therefore difficult to see.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[D]

On 10/28/2012 9:07 PM, Black Iccy wrote:

Long time since I've posted on Usenet.
What I want to do is give some public address system
operators (in a hotel actually), a clear and easy
visualisation of just how loud they have got things
running. A VU meter situation.

What they should be able to do is see, from a distance,
a meter which preferably will have a 270 degree travel arm

Small meters just won't cut the mustard. Ideally, too,
I envisage driving the meter from the amp speaker supply
so that's why I'm not employing electronic level display systems.
Trying to keep things as simple as possible.

It occurs to me that what I really should use is something
like a car's tachometer movement. I know modern units have
internal electronics etc. They would be un-necessary and
unusable so I'd be stripping them out.

In general, what are the movements?
Still D'asonval ?
What sort of FS sensitivity - 1 mA FS?
Anyone played with these things?
Thanks.

I built an LED VU meter years ago. Like 5 green LED's, followed by 2
yellow LED's, followed by 3 red LED's, with them lighting sequentially
with volume level, green to red, fluctuating with the level.
Theoretically, one of these could be any size you want. I'm sure if you
do some searching on LED VU meters, you'll find something.

Dan

 

[Jeff Liebermann]

On Sun, 28 Oct 2012 22:10:53 -0700, D <none@hotmail.com> wrote:

I built an LED VU meter years ago. Like 5 green LED's, followed by 2
yellow LED's, followed by 3 red LED's, with them lighting sequentially
with volume level, green to red, fluctuating with the level.
Theoretically, one of these could be any size you want. I'm sure if you
do some searching on LED VU meters, you'll find something.

That would be an LM3916 IC:
<http://www.ti.com/lit/ds/symlink/lm3916.pdf>
<https://www.google.com/search?q=lm3916+vu+meter&tbm=isch>
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Jeff Liebermann]

On Mon, 29 Oct 2012 15:07:59 +1100, Black Iccy
<Daedelus@whereamIinvalid.com> wrote:

What they should be able to do is see, from a distance,
a meter which preferably will have a 270 degree travel arm

Dual LCD VU meters:
<http://www.sparkfun.com/tutorials/120>
<http://www.youtube.com/watch?v=jxwFfjCVMII>
The LCD meters are 4x5" and $50/ea.
<https://www.sparkfun.com/products/8799>
Probably not big enough to see across a room, but still interesting.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Black Iccy]

On Sun, 28 Oct 2012 22:38:05 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:

https://www.sparkfun.com/products/8799
Probably not big enough to see across a room, but still interesting.

I hear you Jeff. I know the LM dot/bar chips too.
All these things require another power supply to
run them. I'm after something "self-propelled" .

The ideal situation is to take the 200 W,
Step it up to 1,000,000 V and use the spearing arc
to get the barman to turn things down a notch.

Reverting: Just looking at some E-diagrams for
these car tacho's, some seem to have a double winding
as a designate sine/cosine measurement from the chips.
This implies we are still ultimately at an analog system.

 

[Black Iccy]

On Sun, 28 Oct 2012 21:51:17 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:

What distance?

Oh, as far as a deaf and blind barman can manage. About 10 ft max -)
It would be within the bar area domain i.e. not for customer viewing.

and move indicator. The motor would complain, sometimes get hot, but
since the applause was not continuously present, it had time to cool
down.

Motorised is a slight overkill -) I'm thinking of using the
Pwr-Amp output suitably rectified and damped.

Yep. I even got paid to play with them. Maybe if you supplied some
numbers (i.e. distance, size, cost, etc), it might be possible to
offer some sane suggestions?

Pretty much car dashboard size will be OK. Perhaps no more than 3" dia.
They can occasionally wander over to inspect the audio level after being
beaten by a whip (if they ever cared enough)

2. Use a moving mirror. The deflection of the mirror will move a
reflected light beam across the wall or ceiling. The amount of
movement is proportional to the amplitude. The major problem will be
damping the mirror so that it doesn't "ring" or move like sludge.

No, no, no. Its a pub not a disco. -)

 

[Black Iccy]

On Sun, 28 Oct 2012 22:10:53 -0700, D <none@hotmail.com> wrote:

I built an LED VU meter years ago. Like 5 green LED's, followed by 2
yellow LED's, followed by 3 red LED's, with them lighting sequentially
with volume level, green to red, fluctuating with the level.
Theoretically, one of these could be any size you want. I'm sure if you
do some searching on LED VU meters, you'll find something.

Yep. There are kits out there and I could do the same.
Two (three ?) things working against that.

1. Keeping a constant E/I supply to the displaying/sensing device
which would probably be needed at low power levels. Easy to drain
a watt or less at hi-levels (max 200 power amp)
2. Lights get 'missed' in a well lit area.
3. Cost. They won't come at things that cost money (gee. surprise).

 

[N_Cook]

Black Iccy <Daedelus@whereamIinvalid.com> wrote in message
news:gt8s885ei4s7dnl928ci9r6onjclhqvd24@4ax.com...

On Sun, 28 Oct 2012 22:38:05 -0700, Jeff Liebermann <jeffl@cruzio.com
wrote:

https://www.sparkfun.com/products/8799
Probably not big enough to see across a room, but still interesting.


I hear you Jeff. I know the LM dot/bar chips too.
All these things require another power supply to
run them. I'm after something "self-propelled" .

The ideal situation is to take the 200 W,
Step it up to 1,000,000 V and use the spearing arc
to get the barman to turn things down a notch.

Reverting: Just looking at some E-diagrams for
these car tacho's, some seem to have a double winding
as a designate sine/cosine measurement from the chips.
This implies we are still ultimately at an analog system.

A rechargeable with bridge rectifier and some kohmish droppers from the
speaker line?

kohm values from some knowledge of what the pub's normal audio power
throughput is

 

[N_Cook]

When the team hits on a device , my pub could do with one. Amp and controls
in a sideroom with not even a monitor speaker in that room. Why is it beyond
management to put stickers on the volume control scale with numbers of
people in the bar comensurate with speaker audio levels and not the usual
meaningless 0 to 10 numbers.

 

[Jamie]

Black Iccy wrote:

On Sun, 28 Oct 2012 22:38:05 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:


https://www.sparkfun.com/products/8799
Probably not big enough to see across a room, but still interesting.



I hear you Jeff. I know the LM dot/bar chips too.
All these things require another power supply to
run them. I'm after something "self-propelled" .

The ideal situation is to take the 200 W,
Step it up to 1,000,000 V and use the spearing arc
to get the barman to turn things down a notch.

Reverting: Just looking at some E-diagrams for
these car tacho's, some seem to have a double winding
as a designate sine/cosine measurement from the chips.
This implies we are still ultimately at an analog system.
step up transformer of some kind?

Jamie

 

[Jeff Liebermann]

On Mon, 29 Oct 2012 17:46:18 +1100, Black Iccy
<Daedelus@whereamIinvalid.com> wrote:

Oh, as far as a deaf and blind barman can manage. About 10 ft max -)
It would be within the bar area domain i.e. not for customer viewing.

Make it big and easily visible and you have a way of keeping the noise
level down in the bar. Calibrate it in SPL units and label it from
whisper to threshold of pain. I just hate shouting over the music and
the crowd.

You could also program in an upper limit threshold switch. When the
bar noise level reaches the equivalent of a jet engine on takeoff, it
automatically turns off the music and the house lights. Claim it's a
power failure if anyone asks. The noise will subside as everyone
looks around for what happened. A few seconds later, the power comes
back on and life continues as before. Do it often enough, and the
crowd will be trained not to yell so much.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[mike]

On 10/29/2012 9:23 AM, Jeff Liebermann wrote:

On Mon, 29 Oct 2012 17:46:18 +1100, Black Iccy
Daedelus@whereamIinvalid.com> wrote:

Oh, as far as a deaf and blind barman can manage. About 10 ft max -)
It would be within the bar area domain i.e. not for customer viewing.

Make it big and easily visible and you have a way of keeping the noise
level down in the bar. Calibrate it in SPL units and label it from
whisper to threshold of pain. I just hate shouting over the music and
the crowd.

You could also program in an upper limit threshold switch. When the
bar noise level reaches the equivalent of a jet engine on takeoff, it
automatically turns off the music and the house lights.

That's an extremely BAD suggestion.
First thing that's gonna happen is that the lawyers will descend on
him with injury lawsuits and he'll be out of a bar.

Claim it's a

power failure if anyone asks. The noise will subside as everyone
looks around for what happened. A few seconds later, the power comes
back on and life continues as before. Do it often enough, and the
crowd will be trained not to yell so much.

 

[hr(bob) hofmann@att.net]

On Oct 29, 11:23 am, Jeff Liebermann <je...@cruzio.com> wrote:

On Mon, 29 Oct 2012 17:46:18 +1100, Black Iccy

Daede...@whereamIinvalid.com> wrote:
Oh, as far as a deaf and blind barman can manage. About 10 ft max -)
It would be within the bar area domain i.e. not for customer viewing.

Make it big and easily visible and you have a way of keeping the noise
level down in the bar.  Calibrate it in SPL units and label it from
whisper to threshold of pain.  I just hate shouting over the music and
the crowd.

You could also program in an upper limit threshold switch.  When the
bar noise level reaches the equivalent of a jet engine on takeoff, it
automatically turns off the music and the house lights.  Claim it's a
power failure if anyone asks.  The noise will subside as everyone
looks around for what happened.  A few seconds later, the power comes
back on and life continues as before.  Do it often enough, and the
crowd will be trained not to yell so much.
--
Jeff Liebermann     je...@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558begin_of_the_skype_highlighting FREE 831-336-2558

LOL

 

[Michael A. Terrell]

Black Iccy wrote:

On Sun, 28 Oct 2012 22:38:05 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:

https://www.sparkfun.com/products/8799
Probably not big enough to see across a room, but still interesting.

I hear you Jeff. I know the LM dot/bar chips too.
All these things require another power supply to
run them. I'm after something "self-propelled" .

The ideal situation is to take the 200 W,
Step it up to 1,000,000 V and use the spearing arc
to get the barman to turn things down a notch.

Reverting: Just looking at some E-diagrams for
these car tacho's, some seem to have a double winding
as a designate sine/cosine measurement from the chips.
This implies we are still ultimately at an analog system.

GM used to use balanced movements in gauges like that. DC on one
coil, signal on the other. That allowed them to stay accurate, even
with a low battery.


I am building a LCD level meter, and when the signal gets too high it
will cause the monitor output to clip. The same circuit could be used
to drive the main amp. Another approach would be to use the last two
levels to reduce the amp output by 6 or 12 dB, so if it's dropping as
they turn it up (or clipping if they are on the edge) they will back it
off.

 

[Black Iccy]

On Mon, 29 Oct 2012 09:23:54 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:

When the bar noise level reaches the equivalent of a jet engine on takeoff
it automatically turns off the music and the house lights.

Already got that facility. It's called thermal overload protection system.
It works too. Amazing the panic it causes when there's silence and they find
they don't uderstand the problem and where it lies -)

 

[Black Iccy]

On Mon, 29 Oct 2012 10:40:12 -0500, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

step up transformer of some kind?

Jamie

No. Doubt it. This is the sort of thing I'm stumbling across.

http://www.datasheetcatalog.org/datasheet/on_semiconductor/CS8191-D.PDF

Sort of implies a highly idiosyncratic measurement system and, at the least,
a specialised meter movement.

 

[Jeff Liebermann]

On Mon, 29 Oct 2012 09:40:19 -0700, mike <ham789@netzero.net> wrote:

On 10/29/2012 9:23 AM, Jeff Liebermann wrote:
On Mon, 29 Oct 2012 17:46:18 +1100, Black Iccy
Daedelus@whereamIinvalid.com> wrote:

Oh, as far as a deaf and blind barman can manage. About 10 ft max -)
It would be within the bar area domain i.e. not for customer viewing.

Make it big and easily visible and you have a way of keeping the noise
level down in the bar. Calibrate it in SPL units and label it from
whisper to threshold of pain. I just hate shouting over the music and
the crowd.

You could also program in an upper limit threshold switch. When the
bar noise level reaches the equivalent of a jet engine on takeoff, it
automatically turns off the music and the house lights.

That's an extremely BAD suggestion.
First thing that's gonna happen is that the lawyers will descend on
him with injury lawsuits and he'll be out of a bar.

Oh, you're no fun. If it turns into a litigatory exercise, just tell
the judge that the music system blew the circuit breaker and that it
took a few seconds/minutes to reset it. It's always best to have
plausible denial prepared before doing anything risky.

However, it is possible that some patron in the noisy bar will
complain from hearing damage. To prepare for that litigatory event,
the bar should place signs indicating:
"Yelling above 90dB (0.1Pa) prohibited"
along with SPL bar chart and OSHA web site URL. If someone claims
that their hearing was damaged, and that the bar did not take
sufficient precautions to prevent hearing damage, then the sign should
provide sufficient evidence of informed consent by the patrons to be
bombarded with high noise levels. As an extra bonus, it might be
useful too record the sound levels on a strip chart recorder for later
use as evidence.

Claim it's a
power failure if anyone asks. The noise will subside as everyone
looks around for what happened. A few seconds later, the power comes
back on and life continues as before. Do it often enough, and the
crowd will be trained not to yell so much.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Jeff Liebermann]

On Mon, 29 Oct 2012 17:43:23 +1100, Black Iccy
<Daedelus@whereamIinvalid.com> wrote:

On Sun, 28 Oct 2012 22:38:05 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:

https://www.sparkfun.com/products/8799
Probably not big enough to see across a room, but still interesting.


I hear you Jeff. I know the LM dot/bar chips too.

Here's a kit, ready to play:
<http://www.mcmelectronics.com/product/CEBEK-VM-22-/28-22942>

All these things require another power supply to
run them. I'm after something "self-propelled" .

You have heard of batteries? The problem is lighting up a mess of
LED's is going to burn some power. If you must, point some solar
cells at the room lighting and use that to charge the battery. Oh
wait, it's a bar, where the lights are always dim.

Ok, all mechanical and no electronics. Take a large ring with a
diaphragm stretched across the ring. Find a mechanical barometer and
tear it apart. Remove the pressure chamber and connect the actuator
arm to the center of the large drum. Add a bit of fluid damping by
submerging the mechanism in thin oil (5-10wt). When the sound
pressure in the room moves the drum slightly, the barometer mechanism
will indicate the peaks. Patent pending...

The ideal situation is to take the 200 W,
Step it up to 1,000,000 V and use the spearing arc
to get the barman to turn things down a notch.

Reverting: Just looking at some E-diagrams for
these car tacho's, some seem to have a double winding
as a designate sine/cosine measurement from the chips.
This implies we are still ultimately at an analog system.
--

Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Black Iccy]

On Tue, 30 Oct 2012 10:25:09 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:

Ok, all mechanical and no electronics. Take a large ring with a
diaphragm stretched across the ring. Find a mechanical barometer and
tear it apart. Remove the pressure chamber and connect the actuator
arm to the center of the large drum. Add a bit of fluid damping by
submerging the mechanism in thin oil (5-10wt). When the sound
pressure in the room moves the drum slightly, the barometer mechanism
will indicate the peaks. Patent pending...

<Snaps fingers>. That's it. Sheer genius!
A single 2" loudspeaker clamped to the back of a barometer.
Speaker cone has a pressure valve fitted.