Author Topic: Voltage-Controlled Volume Control  (Read 2928 times)

eleanor296

Voltage-Controlled Volume Control
« on: February 20, 2017, 03:35:02 PM »
Heya guys,

currently messing around with stuffing a bunch of pedal guts into a 1U rack and controlling it all via MIDI.

I was looking to put a volume control in my amp's serial FX loop and control the thing via an Arduino, i.e. voltage.  Got any recommendations for circuits to look at?

I'm having a hard time searching for this topic, simply searching for "volume" gives me everything, searching for multiple applicable terms barely returns anything.

LiLFX

Re: Voltage-Controlled Volume Control
« Reply #1 on: February 20, 2017, 04:08:03 PM »
Digital potentiometer?

eleanor296

Re: Voltage-Controlled Volume Control
« Reply #2 on: February 20, 2017, 04:09:27 PM »
That's the brute force way I guess.  Wonder how smooth that'd be.  LED/photocell pair might be another option?

balkanizeyou

Re: Voltage-Controlled Volume Control
« Reply #3 on: February 20, 2017, 04:56:43 PM »
you can use a designated VCA chip (VCA - voltage controlled amplifier).
Or you can search for a discrete VCA design, there's plenty of that on the web (using a LM13700 is a simple way of doing this for example)

PRR

Re: Voltage-Controlled Volume Control
« Reply #4 on: February 20, 2017, 05:17:55 PM »
> control the thing via an Arduino, i.e. voltage.

That's a computer. You can indirectly get a voltage out of it, sure. But bit-banging a digital volume control is more natural. A 256-step control is smooth enough for almost any audio purpose.
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merlinb

Re: Voltage-Controlled Volume Control
« Reply #5 on: February 20, 2017, 05:42:33 PM »
LED+LDR combo, digipot, LM13700, THAT2181, PGA2310, MUSE72320, MDAC, relay array... welcome to my world.

How quiet does it need to be? How many steps? How accurate? How much 'kill' do you need? What taper? How expensive?
« Last Edit: February 20, 2017, 05:46:24 PM by merlinb »

Ice-9

Re: Voltage-Controlled Volume Control
« Reply #6 on: February 20, 2017, 06:05:45 PM »
Have a look at something like the Analog Devices AD5252 non volatile I2C digital pot IC's.
www.stanleyfx.co.uk

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DDD

Re: Voltage-Controlled Volume Control
« Reply #7 on: February 21, 2017, 12:12:08 AM »
LED+LDR definitely is a winner (LED driver should be inertial to avoid scratches from the control pot).
*** Total consumption is about 3-4 mA, that is enough for LED.
Too old to rock'n'roll, too young to die

eleanor296

Re: Voltage-Controlled Volume Control
« Reply #8 on: February 21, 2017, 09:37:23 AM »
LED+LDR combo, digipot, LM13700, THAT2181, PGA2310, MUSE72320, MDAC, relay array... welcome to my world.

How quiet does it need to be? How many steps? How accurate? How much 'kill' do you need? What taper? How expensive?

Sounds like I got some homework to do.

I'm also stuffing a wah in there, seems it's pretty much the same problem/solutions.  Don't mind it costing a few bucks, especially if it's a solution that's simple to implement.

eleanor296

Re: Voltage-Controlled Volume Control
« Reply #9 on: February 21, 2017, 09:46:17 AM »
Have a look at something like the Analog Devices AD5252 non volatile I2C digital pot IC's.

Eyyy bingo, looks cool.