Digital Volume Control

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mhennessy

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Joined 2002
markhennessy.co.uk/
soundNERD said:
Can I use the LM1972, at http://www.national.com/pf/LM/LM1972.html and control it with two pushbuttons, one for up and one for down?

If not, would any National, Maxim or TI chip (I would like to get samples) work for what I want to do?

Thanks, Mike
Click to expand...

No, you would need a microcontroller (such as a PIC or AVR) to generate the serial data required by most of these devices. Checking the datasheets will tell you all you need to know about the format and timing, etc...

An exception to this is the Dallas DS1802, which can be controlled by pushbuttons. I considered it for use in my preamp, you can read what I though here: http://www.mhennessy.f9.co.uk/preamp/analogue_research.htm

Cheers,

Mark ;)
 
jackinnj

jackinnj

Member
Joined 2002
tech-diy.com
Re: Re: Digital Volume Control

mhennessy said:


No, you would need a microcontroller (such as a PIC or AVR) to generate the serial data required by most of these devices. Checking the datasheets will tell you all you need to know about the format and timing, etc...

An exception to this is the Dallas DS1802, which can be controlled by pushbuttons. I considered it for use in my preamp, you can read what I though here: http://www.mhennessy.f9.co.uk/preamp/analogue_research.htm

Cheers,

Mark ;)
Click to expand...
No you don't need a microcontroller -- but it is easier with one -- the LM1971,2,3 are synchronous devices so you either toggle the clock line yourself or use a slow-moving 555, an 8-bit "counter" and a "Parallel in Serial Out" shift register (74HC595) -- bring the Load line "LOW", set the address of the LM1972 (0,1,2), by transmitting 8 bits, then transmit the dB/mute setting (second 8-bits), bring the Load Line "High". Parts to do this are about $1.00.

If using a pushbutton for up down, consider how many milliseconds you want the '555 to run for the full gamut.

"Software" in solder -- the old fashioned way -- still works as Steve Ciarcia is wont to say.
 
K

koolscooby

Member
Joined 2003
bradleyehughes.com
Re: Re: Digital Volume Control

mhennessy said:


No, you would need a microcontroller (such as a PIC or AVR) to generate the serial data required by most of these devices. Checking the datasheets will tell you all you need to know about the format and timing, etc...

An exception to this is the Dallas DS1802, which can be controlled by pushbuttons. I considered it for use in my preamp, you can read what I though here: http://www.mhennessy.f9.co.uk/preamp/analogue_research.htm

Cheers,

Mark ;)
Click to expand...


And let me add, that your pre-amp is really hardcore-style-awesome :)... i plan to build something similar to it when i have abilities even close to yours ;)
 
K

koolscooby

Member
Joined 2003
bradleyehughes.com
soundNERD said:
Well, i donno 2 much about microcontrollers. 2 be honest, ive never used one before. So, whatever is cheap and can be eaily bought. (as always i like free samples).

-Mike
Click to expand...


Well i'm not aware anywhere that you can get PIC's or AVR's for samples, but PIC's are rather cheap... the PIC16F series only requires something like 4 parts external to create a programmer... but if you buy the debugger kit from them ,its agood 200 bucks... well just my recommendation is a pic16f... :)
 
Hybrid fourdoor

Hybrid fourdoor

Member
Joined 2003
Re: Re: Digital Volume Control

mhennessy said:


An exception to this is the Dallas DS1802, which can be controlled by pushbuttons. I considered it for use in my preamp, you can read what I though here: http://www.mhennessy.f9.co.uk/preamp/analogue_research.htm

Cheers,

Mark ;)
Click to expand...

I saw you had lots of problems with clicking during volume change with the digital pots. there a paper over at Maxim that might be of interest to you. It concerns the DS1802, but has an interesting writeup in the beginning about ways to eliminate the clicks in digital pots.

Application note over at Maxim-IC
 
M

mhennessy

Member
Joined 2002
markhennessy.co.uk/
Re: Re: Re: Digital Volume Control

jackinnj said:
No you don't need a microcontroller -- but it is easier with one -- the LM1971,2,3 are synchronous devices so you either toggle the clock line yourself or use a slow-moving 555, an 8-bit "counter" and a "Parallel in Serial Out" shift register (74HC595) -- bring the Load line "LOW", set the address of the LM1972 (0,1,2), by transmitting 8 bits, then transmit the dB/mute setting (second 8-bits), bring the Load Line "High". Parts to do this are about $1.00.

If using a pushbutton for up down, consider how many milliseconds you want the '555 to run for the full gamut.

"Software" in solder -- the old fashioned way -- still works as Steve Ciarcia is wont to say.
Click to expand...

While you're right, would you seriously attempt it these days? I remember playing these games 10 years ago, before the flash PICs were around. I really wouldn't go back, and wouldn't advise anyone to attempt it either. This sort of project is the ideal motivation to learn PIC or AVR. Once you've crossed that hurdle, just think about the possibilities afterwards ;)


koolscooby said:
And let me add, that your pre-amp is really hardcore-style-awesome :)... i plan to build something similar to it when i have abilities even close to yours ;)
Click to expand...

Well, thank you ;)

If it's any encouragement, I didn't know how to programme PICs when I started - see above...


koolscooby said:
Well i'm not aware anywhere that you can get PIC's or AVR's for samples, but PIC's are rather cheap... the PIC16F series only requires something like 4 parts external to create a programmer... but if you buy the debugger kit from them ,its agood 200 bucks... well just my recommendation is a pic16f... :)
Click to expand...

You can get PIC samples from the Microchip website. Very handy ;)


Hybrid fourdoor said:
I saw you had lots of problems with clicking during volume change with the digital pots. there a paper over at Maxim that might be of interest to you.
Click to expand...

Thanks for this - I'll be reading it later...

Interestingly, I've just noticed that there's a DS1802 in my portable Sony MD recorder - it's used to give volume control to the headphone output. And, it sounds pretty good to me...

Cheers,

Mark
 
jackinnj

jackinnj

Member
Joined 2002
tech-diy.com
Re: Re: Re: Re: Digital Volume Control

mhennessy said:

While you're right, would you seriously attempt it these days? I remember playing these games 10 years ago, before the flash PICs were around. I really wouldn't go back, and wouldn't advise anyone to attempt it either. This sort of project is the ideal motivation to learn PIC or AVR. Once you've crossed that hurdle, just think about the possibilities afterwards ;)
Click to expand...
I use PicBasic Pro and an MELabs serial programmer -- but anyone who uses PIC's probably has '595's and '165's hanging around.

That's OK, I had to explain Ohm's law to someone who was MCSE certified the other day.
 
E

elektroman

Member
Joined 2004
Digital volume control

You can control volume with a DS 1802 ic. It's a digital volume control with 50k resistance.I think it can be controlled with 2 bottoms.Or it doesn't works you can built a simple circuit with an 74193 counter,an 4016 analog switch and some resistance.
I have this circuit,if I find it i share here.
 
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