On car and home HiFi I have a knob to control the volume. It is not a
variable resistor - it turns infinately. I guess is somehow creates a
proportional and directional signal to the amplifier - but what is in the
mechanism and how does it work?

DerbyBorn wrote:

On car and home HiFi I have a knob to control the volume. It is not a
variable resistor - it turns infinately.

An incremental rotary encoder and either digital control of the amp
gain, or software scales the volume accordingly while amp runs at fixed
gain.

on 30/11/2016, DerbyBorn supposed :
On car and home HiFi I have a knob to control the volume. It is not a
variable resistor - it turns infinately. I guess is somehow creates a
proportional and directional signal to the amplifier - but what is in the
mechanism and how does it work?

They now use an opto-coupler, basically they (two pairs, so they get a
direction) shine a beam of light through a segmented disk. The output
of which controls an IC to vary the volume. They are used on many
things - volume controls, tuning controls, microwave ovens and etc..
Anything which needs a rotary control to change a value.

On 30/11/2016 10:52, DerbyBorn wrote:
On car and home HiFi I have a knob to control the volume. It is not a
variable resistor - it turns infinately. I guess is somehow creates a
proportional and directional signal to the amplifier - but what is in the
mechanism and how does it work?

Not unlike a stepper motor but with the coils connected to a sensor that
determines direction and rate of rotation from the clicks.

https://en.wikipedia.org/wiki/Rotary...rotary_encoder

Prior to that there were absolute position encoders using Grey codes
that would allow you to read the angle (but costly to do at high
precision). Telescope drives and CNC tools use them for feedback.

--
Regards,
Martin Brown

On 30/11/16 12:22, Martin Brown wrote:
On 30/11/2016 10:52, DerbyBorn wrote:
On car and home HiFi I have a knob to control the volume. It is not a
variable resistor - it turns infinately. I guess is somehow creates a
proportional and directional signal to the amplifier - but what is in the
mechanism and how does it work?

Not unlike a stepper motor but with the coils connected to a sensor that
determines direction and rate of rotation from the clicks.

https://en.wikipedia.org/wiki/Rotary...rotary_encoder

Prior to that there were absolute position encoders using Grey codes
that would allow you to read the angle (but costly to do at high
precision). Telescope drives and CNC tools use them for feedback.

When I built one back in the 70's the cheapest was a light source, a 50
50 slotted wheel., and two photo detectors, plus a bit of CMOS logic

Coils and magnets are a no no as they don't detect *very slow* movement.

--
Truth welcomes investigation because truth knows investigation will lead
to converts. It is deception that uses all the other techniques.

On 30/11/16 11:53, Harry Bloomfield wrote:
on 30/11/2016, DerbyBorn supposed :
On car and home HiFi I have a knob to control the volume. It is not a
variable resistor - it turns infinately. I guess is somehow creates a
proportional and directional signal to the amplifier - but what is in
the mechanism and how does it work?

They now use an opto-coupler, basically they (two pairs, so they get a
direction) shine a beam of light through a segmented disk. The output of
which controls an IC to vary the volume. They are used on many things -
volume controls, tuning controls, microwave ovens and etc.. Anything
which needs a rotary control to change a value.

Not all. Before optical some used multiple sliding contacts, and become
annoyingly noisy. I had a mini system and even a Sony walkman with
issues like this where at a random point the contacts would become open
circuit and assist in digitally creating a gain setting not too distant
from the number 11.

Then you have tinnitus, lost teeth and sore joints for a few hours after
the unscheduled urgent launch to explore the galaxy far far away beyond
the ceiling in your room....

--
Adrian C

In article ,
Adrian Caspersz wrote:
They now use an opto-coupler, basically they (two pairs, so they get a
direction) shine a beam of light through a segmented disk. The output of
which controls an IC to vary the volume. They are used on many things -
volume controls, tuning controls, microwave ovens and etc.. Anything
which needs a rotary control to change a value.

Not all. Before optical some used multiple sliding contacts, and become
annoyingly noisy. I had a mini system and even a Sony walkman with
issues like this where at a random point the contacts would become open
circuit and assist in digitally creating a gain setting not too distant
from the number 11.

Some use hall effect sensors too. I'd say that easier than messing about
with light beams.

--
*When I'm not in my right mind, my left mind gets pretty crowded *

Dave Plowman London SW
To e-mail, change noise into sound.

On Wednesday, 30 November 2016 12:49:03 UTC, Dave Plowman (News) wrote:
In article ,
Adrian Caspersz wrote:
They now use an opto-coupler, basically they (two pairs, so they get a
direction) shine a beam of light through a segmented disk. The output of
which controls an IC to vary the volume. They are used on many things -
volume controls, tuning controls, microwave ovens and etc.. Anything
which needs a rotary control to change a value.

Not all. Before optical some used multiple sliding contacts, and become
annoyingly noisy. I had a mini system and even a Sony walkman with
issues like this where at a random point the contacts would become open
circuit and assist in digitally creating a gain setting not too distant
from the number 11.

Some use hall effect sensors too. I'd say that easier than messing about
with light beams.

A cheap and popular method is still used by mice, well not lots of mouses but optical mice still use an LED. They don't use a light chopper but 'take' a picture of teh surface table and use that and subsequent movments to work out it;s position. I;'m not sure if hall effect sensors are still used for this sort of thin unless in a specialsed area of use.



--
*When I'm not in my right mind, my left mind gets pretty crowded *

Dave Plowman London SW
To e-mail, change noise into sound.

On 30/11/16 10:52, DerbyBorn wrote:
On car and home HiFi I have a knob to control the volume. It is not a
variable resistor - it turns infinately. I guess is somehow creates a
proportional and directional signal to the amplifier - but what is in the
mechanism and how does it work?

In a binary fashion.

IMHO it has only two settings - too quiet or too loud...

--

Jeff

In article ,
whisky-dave wrote:
Some use hall effect sensors too. I'd say that easier than messing
about with light beams.

A cheap and popular method is still used by mice, well not lots of
mouses but optical mice still use an LED. They don't use a light chopper
but 'take' a picture of teh surface table and use that and subsequent
movments to work out it;s position. I;'m not sure if hall effect sensors
are still used for this sort of thin unless in a specialsed area of use.

I'd guess you'd need a much finer resolution with a mouse, though.

--
*Red meat is not bad for you. Fuzzy green meat is bad for you.

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:

whisky-dave wrote:

A cheap and popular method is still used by mice, well not lots of
mouses but optical mice still use an LED. They don't use a light chopper
but 'take' a picture of teh surface table

I'd guess you'd need a much finer resolution with a mouse, though.

My DAB radio does a full rotation in 20 clicks but volume goes from 0 to
32 so needs more than a full rotation, my car radio is probably similar.

On Wednesday, 30 November 2016 14:03:05 UTC, Dave Plowman (News) wrote:
In article ,
whisky-dave wrote:
Some use hall effect sensors too. I'd say that easier than messing
about with light beams.

A cheap and popular method is still used by mice, well not lots of
mouses but optical mice still use an LED. They don't use a light chopper
but 'take' a picture of teh surface table and use that and subsequent
movments to work out it;s position. I;'m not sure if hall effect sensors
are still used for this sort of thin unless in a specialsed area of use..

I'd guess you'd need a much finer resolution with a mouse, though.

Seems quite possible nowadays as tha's how the majoroty of mice costing more than £10 work. I belive you can stil buy mice with a trackball and a chopper circuit if you really want to.

Some are optical, some are just pulse generators.
I think its a way to stop that nasty issue of crackling as they wear and
get damp as often is the way in cars.
Most simply then are driving the logic on one part of the control chip. How
it works is rather academic as often you need the actual proper part these
days.
I personally do not like them as as a blind person nowadays, there seems in
most cases to be no way to actually calibrate the knob as anywhere is
anywhere as on switch on it might be as it was last time or set to some
arbitrary point for the system. My first encounter with this was on a
minidisc recorder. Not only did it have continuous clicks, but if you move
it a short distance fast, it actually incremented faster than the normal
amount, so some kind of speed of movement was programmed in just to add more
confusion. add to that a mode where it looked at the digitally connected
source for max levels if it was a dacd then confusion reigned supreme.
Bring back the analogue pot.

Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"DerbyBorn" wrote in message
2.236...
On car and home HiFi I have a knob to control the volume. It is not a
variable resistor - it turns infinately. I guess is somehow creates a
proportional and directional signal to the amplifier - but what is in the
mechanism and how does it work?

Often they also have a push in action to fix the volume from getting moved
or in some cases to set it so it comes on at that volume when turned off.
Too much cleverness being built in to something that does not really need
it in my view.
I have one of these on a radio to move between preset stations, but the
clickery bit is knackerd and now and again it has a mind of its own and
moves between stations in a demented and anti social manner.
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"The Natural Philosopher" wrote in message
news
On 30/11/16 12:22, Martin Brown wrote:
On 30/11/2016 10:52, DerbyBorn wrote:
On car and home HiFi I have a knob to control the volume. It is not a
variable resistor - it turns infinately. I guess is somehow creates a
proportional and directional signal to the amplifier - but what is in
the
mechanism and how does it work?

Not unlike a stepper motor but with the coils connected to a sensor that
determines direction and rate of rotation from the clicks.

https://en.wikipedia.org/wiki/Rotary...rotary_encoder

Prior to that there were absolute position encoders using Grey codes
that would allow you to read the angle (but costly to do at high
precision). Telescope drives and CNC tools use them for feedback.

When I built one back in the 70's the cheapest was a light source, a 50 50
slotted wheel., and two photo detectors, plus a bit of CMOS logic

Coils and magnets are a no no as they don't detect *very slow* movement.

--
Truth welcomes investigation because truth knows investigation will lead
to converts. It is deception that uses all the other techniques.

DerbyBorn wrote

On car and home HiFi I have a knob to control the volume.
It is not a variable resistor - it turns infinately. I guess is
somehow creates a proportional and directional signal to the
amplifier - but what is in the mechanism and how does it work?

There's a whole variety of ways. With smartphones its just a way
of indicating to the phone what you want volume wise by moving
the slider on the touch screen or pressing buttons on the side of
the phone. With some things like my bluetooth headset, the buttons
do dual duty, they are used to raise and lower the volume and also
to skip forward and backwards depending on how you press them.

In other words, no electrical connection at all that has any direct
effect on the amplifier, just instructions to the computer about
what you want done to the gain on the amplifier.

Brian - bear in mind that this sopisticated changes are to benefit the
manufacturer - not the user. Think how many potentiometers were saved by
making remote control standard!

Many radios in cars have a setting to the switch on volume level - hidden
in the settings.

In article 6,
DerbyBorn wrote:
Many radios in cars have a setting to the switch on volume level -
hidden in the settings.

I'd assumed that's why this sort of device came into use.

--
*Rehab is for quitters.

Dave Plowman London SW
To e-mail, change noise into sound.

On Thu, 01 Dec 2016 00:25:57 +0000, Dave Plowman (News) wrote:

In article 6,
DerbyBorn wrote:
Many radios in cars have a setting to the switch on volume level -
hidden in the settings.

I'd assumed that's why this sort of device came into use.

It also has to be a 'soft' control so a dofferent level can be used for
traffic reports, etc.



--
My posts are my copyright and if @diy_forums or Home Owners' Hub
wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
*lightning surge protection* - a w_tom conductor

Brian Gaff wrote

Some are optical, some are just pulse generators.
I think its a way to stop that nasty issue of crackling as they wear and
get damp as often is the way in cars.

Most simply then are driving the logic on one part of the control chip.
How it works is rather academic as often you need the actual proper part
these days.

I personally do not like them as as a blind person nowadays, there seems
in most cases to be no way to actually calibrate the knob as anywhere is
anywhere as on switch on it might be as it was last time

Trivially easy to keep track of the volume last used, save that
in nvram or just loose that setting on a car battery change.

or set to some arbitrary point for the system. My first encounter with
this was on a minidisc recorder. Not only did it have continuous clicks,
but if you move it a short distance fast, it actually incremented faster
than the normal amount, so some kind of speed of movement was programmed
in just to add more confusion.

Its actually a much better user interface.

add to that a mode where it looked at the digitally connected source for
max levels if it was a dacd then confusion reigned supreme.
Bring back the analogue pot.

No thanks, it wont even fit in any phone.

"DerbyBorn" wrote in message
2.236...
On car and home HiFi I have a knob to control the volume. It is not a
variable resistor - it turns infinately. I guess is somehow creates a
proportional and directional signal to the amplifier - but what is in the
mechanism and how does it work?

Dave Plowman (News) wrote:

DerbyBorn wrote:

Many radios in cars have a setting to the switch on volume level -
hidden in the settings.

I'd assumed that's why this sort of device came into use.

Plus it allows the same knob (in conjunction with a mode button) to
alter tone, balance etc.

On Thursday, 1 December 2016 10:00:05 UTC, Andy Burns wrote:
Dave Plowman (News) wrote:

DerbyBorn wrote:

Many radios in cars have a setting to the switch on volume level -
hidden in the settings.

I'd assumed that's why this sort of device came into use.

Plus it allows the same knob (in conjunction with a mode button) to
alter tone, balance etc.

There'e nothing quite like having multiple uses for your knob is there :-)

On 30/11/16 22:20, DerbyBorn wrote:
Brian - bear in mind that this sopisticated changes are to benefit the
manufacturer - not the user. Think how many potentiometers were saved by
making remote control standard!

That is more than amusing. Its the truth.

A quality potentiometer wired into a board probably adds £1 to its
final cost, and is a source of wear and short product life.

Trying to get rid of mechanical things has been a drive in electronics
ever since valves went out of fashion.

I am working on a hobby project involving a piece of digital electronics
that I want to control via loads of pots.

I COULD use a mouse or a touchscreen, but I like the old fashioned feel
of pots...

Using that as control inputs will be the single most expensive feature
in the design.

Many radios in cars have a setting to the switch on volume level - hidden
in the settings.


Mine just reverts to where it was when I switched off.



--
Gun Control: The law that ensures that only criminals have guns.

On 01/12/16 10:00, Andy Burns wrote:
Dave Plowman (News) wrote:

DerbyBorn wrote:

Many radios in cars have a setting to the switch on volume level -
hidden in the settings.

I'd assumed that's why this sort of device came into use.

Plus it allows the same knob (in conjunction with a mode button) to
alter tone, balance etc.

one button plus one knob cheaper than 5 knobs, and uses less panel space.


--
"When a true genius appears in the world, you may know him by this sign,
that the dunces are all in confederacy against him."

Jonathan Swift.

On Wednesday, 30 November 2016 22:20:16 UTC, DerbyBorn wrote:
Brian - bear in mind that this sopisticated changes are to benefit the
manufacturer - not the user. Think how many potentiometers were saved by
making remote control standard!

I remember the protests outside parilment all the banners and logos save the potentiometers, oh wait or was it whales ?


Many radios in cars have a setting to the switch on volume level - hidden
in the settings.