how do I add preset memory and digital control of analogue circuit ?

[clubsprint]

G'day all
I've designed and am in the process of making a speaker emulator for Pro
Audio recording application
and would like to add preset memory and midi program change to the unit.
Trouble is I'm not quite sure how to go about it. I'm looking for digital
control of 4 pots and half a dozen switches. If anyone could please point me
in the direction of what hardware I need and how it's set up (books,
articles websites etc.) it would be greatly appreciated. I did electronics
at Box Hill TAFE 25 years ago and I'm just getting back into it for fun
after spending years in audio sales and PC networks. Building stuff is much
more fun.

 

[Tim Wescott]

G'day all
I've designed and am in the process of making a speaker emulator for Pro
Audio recording application
and would like to add preset memory and midi program change to the unit.
Trouble is I'm not quite sure how to go about it. I'm looking for digital
control of 4 pots and half a dozen switches. If anyone could please point me
in the direction of what hardware I need and how it's set up (books,
articles websites etc.) it would be greatly appreciated. I did electronics
at Box Hill TAFE 25 years ago and I'm just getting back into it for fun
after spending years in audio sales and PC networks. Building stuff is much
more fun.

Is there a reason not to use relays for the switches?

Mouser used to sell motorized potentiometers -- I'd check there. Even if
you're in Oz or elsewhere outside of the US the Mouser part may lead you
to a manufacturer, which may lead you to an in-country distributor.

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

 

[Tom2000]

G'day all
I've designed and am in the process of making a speaker emulator for Pro
Audio recording application
and would like to add preset memory and midi program change to the unit.
Trouble is I'm not quite sure how to go about it. I'm looking for digital
control of 4 pots and half a dozen switches. If anyone could please point me
in the direction of what hardware I need and how it's set up (books,
articles websites etc.) it would be greatly appreciated. I did electronics
at Box Hill TAFE 25 years ago and I'm just getting back into it for fun
after spending years in audio sales and PC networks. Building stuff is much
more fun.

There are lots of ways to switch, starting with humble old relays and
moving up from there. How you switch depends upon what you switch.
You're the judge of the best method, depending upon your requirements.

Pots are also a concern when you mention "Pro Audio." I'd suggest you
Google for keywords 'digital potentiometer' then look at some data
sheets for the chips you'll find. Are digital pots compatible with
your system requirements?

If not, there are motorized mechanical pots out there that have the
same electrical characteristics as standard pots. One of these driven
by a stepper motor might be compatible with computer control,
providing repeatibility of its settings.

Once you know what switches and pots are compatible with your system
requirements, we can move on toward automating the arrangement.

Assuming, of course, the folks in rec.tech don't point you to an
off-the-shelf solution right off the bat.

Tom

 

[Arny Krueger]

I've designed and am in the process of making a speaker emulator for Pro
Audio recording application
and would like to add preset memory and midi program change to the unit.

A modern device of that nature would be DSP-based, and those settings would
be DSP parameters under program control. Problem solved!

Trouble is I'm not quite sure how to go about it. I'm looking for digital
control of 4 pots and half a dozen switches.

There are such things as digital potentiometers, and there are also such
things as digitally-controlled analog chips that serve a similar purpose.
There are definately electronic switches that can be digitally-controlled.

If anyone could please point me
in the direction of what hardware I need and how it's set up (books,
articles websites etc.) it would be greatly appreciated.

Check the leading manfactuers of mixed-signal chips, such as National and
TI.

Ask this question in the Usenet DSP group.

 

[Michael R. Kesti]

G'day all
I've designed and am in the process of making a speaker emulator for Pro
Audio recording application
and would like to add preset memory and midi program change to the unit.
Trouble is I'm not quite sure how to go about it. I'm looking for digital
control of 4 pots and half a dozen switches. If anyone could please point me
in the direction of what hardware I need and how it's set up (books,
articles websites etc.) it would be greatly appreciated.

One way to get where you want to go is to use digital potentiometers and
switches/multiplexers such as those offered by Maxim/Dallas. You can check
them out at http://www.maxim-ic.com/ where many useful data sheets and app
notes may be obtained. That's the easy part. The hard part is that you
will also need to incorporate and program a microprocessor to control these
devices, store the presets, and support the MIDI communication.

If I was still doing consulting/contract engineering then this is the point
where I would offer my services but, alas, I am again a corporate carpet
walking, cubicle dwelling, wage slave. ;-)

I did electronics
at Box Hill TAFE 25 years ago and I'm just getting back into it for fun
after spending years in audio sales and PC networks. Building stuff is much
more fun.

Roger that!

 

[Richard Crowley]

"clubsprint" wrote ...

I've designed and am in the process of making a speaker
emulator for Pro Audio recording application
and would like to add preset memory and midi program
change to the unit. Trouble is I'm not quite sure how to
go about it. I'm looking for digital control of 4 pots and
half a dozen switches. If anyone could please point me
in the direction of what hardware I need and how it's set
up (books, articles websites etc.) it would be greatly
appreciated. I did electronics at Box Hill TAFE 25 years
ago and I'm just getting back into it for fun after spending
years in audio sales and PC networks. Building stuff is much
more fun.

A typical logic-controlled device is the common 4066
CMOS quad bilateral switch for low-level (audio, etc.)
signals. There are now solid-state devices for higher-
power switching in addition to the perinneal favorite
relays.

Both motorized physical pots and "digital pots" are
available for logic-controlled adjustment of pot settings.
For example, www.digikey.com shows over 3400
different kinds of digital pot ICs.

Motorized pots are frequent favorites with several
surplus electronic web vendors. www.allelectronics.com
usually has at least one or two, but none at the moment.

One of my favorite vendors is www.sparkfun.com
You can certainly find a microcontroller solution
there that is inexpensive. Some of them (like the
"PIC-Axe" series) are simple to program and cheap
to play with (little more than a serial cable from
your computer). There are likely MIDI-decoding
software routines for many of those micro-controllers
available free online.

 

[Eeyore]

G'day all
I've designed and am in the process of making a speaker emulator for Pro
Audio recording application
and would like to add preset memory and midi program change to the unit.
Trouble is I'm not quite sure how to go about it. I'm looking for digital
control of 4 pots and half a dozen switches. If anyone could please point me
in the direction of what hardware I need and how it's set up (books,
articles websites etc.) it would be greatly appreciated. I did electronics
at Box Hill TAFE 25 years ago and I'm just getting back into it for fun
after spending years in audio sales and PC networks. Building stuff is much
more fun.

You're really going to need a microprocessor/microcontroller to do this and
you'll have to program it yourself. Are you up to that ?

Graham

 

[Jamie]

G'day all
I've designed and am in the process of making a speaker emulator for Pro
Audio recording application
and would like to add preset memory and midi program change to the unit.
Trouble is I'm not quite sure how to go about it. I'm looking for digital
control of 4 pots and half a dozen switches. If anyone could please point me
in the direction of what hardware I need and how it's set up (books,
articles websites etc.) it would be greatly appreciated. I did electronics
at Box Hill TAFE 25 years ago and I'm just getting back into it for fun
after spending years in audio sales and PC networks. Building stuff is much
more fun.

There's a good place to start.

http://www.maxim-ic.com/products/digi_pot/

 

[Scott Dorsey]

I've designed and am in the process of making a speaker emulator for Pro
Audio recording application
and would like to add preset memory and midi program change to the unit.
Trouble is I'm not quite sure how to go about it. I'm looking for digital
control of 4 pots and half a dozen switches. If anyone could please point me
in the direction of what hardware I need and how it's set up (books,
articles websites etc.) it would be greatly appreciated. I did electronics
at Box Hill TAFE 25 years ago and I'm just getting back into it for fun
after spending years in audio sales and PC networks. Building stuff is much
more fun.

The cheap way is to use a CMOS pot replacement; Maxim makes a bunch of them
that are very popular.

The expensive way is to use an attenuator built with relays and resistors.
This will invariably sound better but in plenty of applications it doesn't
matter.

There are all sorts of gadgets that will give you parallel port outputs
from whatever source you have.
--scott

 

[clubsprint]

Great link, thanks.

One way to get where you want to go is to use digital potentiometers and
switches/multiplexers such as those offered by Maxim/Dallas. You can
check
them out at http://www.maxim-ic.com/ where many useful data sheets and app
notes may be obtained. That's the easy part. The hard part is that you
will also need to incorporate and program a microprocessor to control
these
devices, store the presets, and support the MIDI communication.

If I was still doing consulting/contract engineering then this is the
point
where I would offer my services but, alas, I am again a corporate carpet
walking, cubicle dwelling, wage slave. ;-)


Roger that!

--
========================================================================
Michael Kesti | "And like, one and one don't make
| two, one and one make one."
mrkesti at hotmail dot com | - The Who, Bargain

 

[clubsprint]

Thanks

A modern device of that nature would be DSP-based, and those settings
would be DSP parameters under program control. Problem solved!


There are such things as digital potentiometers, and there are also such
things as digitally-controlled analog chips that serve a similar purpose.
There are definately electronic switches that can be digitally-controlled.


Check the leading manfactuers of mixed-signal chips, such as National and
TI.

Ask this question in the Usenet DSP group.

 

[clubsprint]

Thanks

There are lots of ways to switch, starting with humble old relays and
moving up from there. How you switch depends upon what you switch.
You're the judge of the best method, depending upon your requirements.

Pots are also a concern when you mention "Pro Audio." I'd suggest you
Google for keywords 'digital potentiometer' then look at some data
sheets for the chips you'll find. Are digital pots compatible with
your system requirements?

If not, there are motorized mechanical pots out there that have the
same electrical characteristics as standard pots. One of these driven
by a stepper motor might be compatible with computer control,
providing repeatibility of its settings.

Once you know what switches and pots are compatible with your system
requirements, we can move on toward automating the arrangement.

Assuming, of course, the folks in rec.tech don't point you to an
off-the-shelf solution right off the bat.

Tom

 

[clubsprint]

Thanks

Is there a reason not to use relays for the switches?

Mouser used to sell motorized potentiometers -- I'd check there. Even if
you're in Oz or elsewhere outside of the US the Mouser part may lead you
to a manufacturer, which may lead you to an in-country distributor.

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

 

[clubsprint]

Great links, especially Sparkfun
Thanks

"clubsprint" wrote ...

A typical logic-controlled device is the common 4066
CMOS quad bilateral switch for low-level (audio, etc.)
signals. There are now solid-state devices for higher-
power switching in addition to the perinneal favorite
relays.

Both motorized physical pots and "digital pots" are
available for logic-controlled adjustment of pot settings.
For example, www.digikey.com shows over 3400 different kinds of digital
pot ICs.
Motorized pots are frequent favorites with several surplus electronic web
vendors. www.allelectronics.com usually has at least one or two, but none
at the moment.

One of my favorite vendors is www.sparkfun.com
You can certainly find a microcontroller solution there that is
inexpensive. Some of them (like the
"PIC-Axe" series) are simple to program and cheap
to play with (little more than a serial cable from your computer). There
are likely MIDI-decoding
software routines for many of those micro-controllers available free
online.

 

[clubsprint]

You're really going to need a microprocessor/microcontroller to do this
and
you'll have to program it yourself. Are you up to that ?

Graham

Guess we'll find out.

 

[clubsprint]

Thanks

There's a good place to start.

http://www.maxim-ic.com/products/digi_pot/

 

[clubsprint]

Thanks

The cheap way is to use a CMOS pot replacement; Maxim makes a bunch of
them
that are very popular.

The expensive way is to use an attenuator built with relays and resistors.
This will invariably sound better but in plenty of applications it doesn't
matter.

There are all sorts of gadgets that will give you parallel port outputs
from whatever source you have.
--scott

 

[Mogens V.]

G'day all
I've designed and am in the process of making a speaker emulator for Pro
Audio recording application
and would like to add preset memory and midi program change to the unit.
Trouble is I'm not quite sure how to go about it. I'm looking for digital
control of 4 pots and half a dozen switches. If anyone could please point me
in the direction of what hardware I need and how it's set up (books,
articles websites etc.) it would be greatly appreciated. I did electronics
at Box Hill TAFE 25 years ago and I'm just getting back into it for fun
after spending years in audio sales and PC networks. Building stuff is much
more fun.

That would be the ADA MicroCab speaker emulator, right?
Fun coinsidense.. same username, electronics experience et al..:
http://www.adadepot.com/forum/index.php/topic,8938.0.html

Only a few days after I depicted the unreadable components for you (yes,
I'm van Sinn at the depot), and mentioned I might build my own _copy_
with some controls..
At the adadepot, we all honour the ADA legacy, so please.. at least
write you wish to add programmability to an ADA _recreation_ ..

 

[Mogens V.]

clubsprint wrote:




You're really going to need a microprocessor/microcontroller to do this and
you'll have to program it yourself. Are you up to that ?

Graham

Yup, not a big task with a 20-pin PIC, eeprom, a few MIDI IFC parts, a
few 4066's and optocoupled pots - and some assembly programming..

 

[Jamie]

Guess we'll find out.

Don't let Mr. Ham scare you off, once you get a fell for the little
uC's, you'll wonder why you stayed away so long.. They solve many hours
or design and labor..