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

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.

Reply to
clubsprint
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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
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Reply to
Tim Wescott

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

Reply to
Tom2000

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.

Reply to
Arny Krueger

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

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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!

--
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          Michael Kesti            |  "And like, one and one don\'t make
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Reply to
Michael R. Kesti

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,

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shows over 3400 different kinds of digital pot ICs.

Motorized pots are frequent favorites with several surplus electronic web vendors.

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usually has at least one or two, but none at the moment.

One of my favorite vendors is

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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.

Reply to
Richard Crowley

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

Reply to
Eeyore

There's a good place to start.

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"I\'m never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
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Reply to
Jamie

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

--
"C\'est un Nagra.  C\'est suisse, et tres, tres precis."
Reply to
Scott Dorsey

Great link, thanks.

Reply to
clubsprint

Thanks

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clubsprint

Thanks

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clubsprint

Thanks

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clubsprint

Reply to
clubsprint

Guess we'll find out.

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clubsprint

Thanks

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clubsprint

Reply to
clubsprint

That would be the ADA MicroCab speaker emulator, right? Fun coinsidense.. same username, electronics experience et al..:

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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_ ..

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Kind regards,
Mogens V.
Reply to
Mogens V.

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..

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Kind regards,
Mogens V.
Reply to
Mogens V.

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..

--
"I\'m never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
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Reply to
Jamie

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