Author |
Message |
jackdamery
Joined: Apr 26, 2010 Posts: 75 Location: UK
|
Posted: Thu Jan 17, 2013 11:53 am Post subject:
Is there such a thing as a digitally controlled ADSR? |
|
|
I was wondering if any chips or designs existed for a digitally controlled ADSR. I'd like to stick such a thing on my vco to save building one from components. |
|
Back to top
|
|
|
jackdamery
Joined: Apr 26, 2010 Posts: 75 Location: UK
|
Posted: Thu Jan 17, 2013 11:55 am Post subject:
|
|
|
Now I think about it, I suppose in essence it would be a digitally controlled amplifier. |
|
Back to top
|
|
|
minisystem
Joined: Nov 16, 2012 Posts: 35 Location: Toronto
|
|
Back to top
|
|
|
bubzy
Joined: Oct 27, 2010 Posts: 594 Location: United Kingdom
Audio files: 64
|
Posted: Fri Jan 18, 2013 12:07 am Post subject:
|
|
|
ive recently been messing about with a DAC on an arduino after reading elmegils post on the arduino subforum. with this method its quite attainable, and very configurable too. _________________ _Richard_ |
|
Back to top
|
|
|
elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
|
Posted: Fri Jan 18, 2013 6:22 am Post subject:
|
|
|
Speaking of which, I was just working on building a shield that has two MCP4922's and a few op amps for buffers. My original thought was to proceed on some of the MIDI->CV speculation I was doing a few months back, but I realized as I was going along that basically I'm creating a shield that could be used for envelopes or any other set of 4 CVs and two square signals (gate & trigger for the MIDI application). Quadrature LFO came to mind too.
Unfortunately it's just a proto shield with wires running every which way; I have not made any headway with eagle doing actual boards, but I will share the circuit when I'm done (it's really pretty simple, so...). |
|
Back to top
|
|
|
rjh
Joined: Jan 20, 2013 Posts: 12 Location: Sweden
|
Posted: Sun Jan 20, 2013 5:13 am Post subject:
|
|
|
Not sure about digitally controlled amplifiers, but there are digital controlled potentiometers (SPI or I2C). I haven't experimented with it but I guess it could potentially be used in a simple op-amp amplifier configuration to create a DCA. I know at least Microchip and Analog Devices makes them. |
|
Back to top
|
|
|
elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
|
Posted: Sun Jan 20, 2013 7:27 am Post subject:
|
|
|
I bought some of the microchip ones, 10K, from SparkFun a while back. It's an MCP4131-103. They also have 5k, 50k, and 100k variants.
One unfortunate thing is they only have an operating voltage up to 5.5V which will make them more difficult to use in the typical 12V or 15V synth circuit. |
|
Back to top
|
|
|
rjh
Joined: Jan 20, 2013 Posts: 12 Location: Sweden
|
Posted: Sun Jan 20, 2013 8:05 am Post subject:
|
|
|
elmegil wrote: |
One unfortunate thing is they only have an operating voltage up to 5.5V which will make them more difficult to use in the typical 12V or 15V synth circuit. |
That's good to know. Looked up some other ones and it seam to be the same. Maxim makes a few that can handle 8v but not more. Though I'm guessing if you're working in the digital domain to begin with you're probably working in the 0-5v range. |
|
Back to top
|
|
|
bubzy
Joined: Oct 27, 2010 Posts: 594 Location: United Kingdom
Audio files: 64
|
Posted: Sun Jan 20, 2013 8:32 am Post subject:
|
|
|
thats not a problem at all,
use an op amp and boost the voltage up 3x
0-5 becomes 0-15. _________________ _Richard_ |
|
Back to top
|
|
|
rjh
Joined: Jan 20, 2013 Posts: 12 Location: Sweden
|
Posted: Sun Jan 20, 2013 8:43 am Post subject:
|
|
|
more importantly scale / offset the signal first. Not very hard, but inconvenient |
|
Back to top
|
|
|
JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
|
Posted: Sun Jan 20, 2013 1:25 pm Post subject:
|
|
|
digital stuff is tending toward lower and lower voltages. I see lots of applications where 3.3volts is the standard. I see more and more digital parts that are 2.2v. Lower voltage digital circuits tend to use less power and are usually faster because the signals have less "distance" to travel when changing state.
As bubzy said, when it gets to a place where the outside world wants to see higher voltages, then amplify.
I mess with dsPICs at 3.3 volts. The DACs barely output 1 volt. So I amplify. Some people freak out about amplifying because there's always a bit of noise - but hey show me any noise free circuit and you win a prize. If the noise is low level enough that you don't hear it, then it doesn't matter. Yeah, it's another part to purchase and solder. Yep. Oh well. With SMT, you can cram all kinds of crap on a board now unlike the old days when you could actually see the parts you're soldering... _________________ FPGA, dsPIC and Fatman Synth Stuff
Time flies like a banana. Fruit flies when you're having fun. BTW, Do these genes make my ass look fat? corruptio optimi pessima
|
|
Back to top
|
|
|
elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
|
Posted: Sun Jan 20, 2013 4:03 pm Post subject:
|
|
|
Didn't mean to say they were a LOT more difficult |
|
Back to top
|
|
|
JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
|
Posted: Sun Jan 20, 2013 5:38 pm Post subject:
|
|
|
To answer the OP's question "Is there such a thing as a digitally controlled ADSR?"
The PAiA Fatman has a hybrid digital/analog ADSR and ASR. The ramp generating parts are capacitors and resistors while the level sensing logic parts are actually code running in the MIDI controller microprocessor.
I have also personally written code to be an ADSR within a digital design without any analog help. _________________ FPGA, dsPIC and Fatman Synth Stuff
Time flies like a banana. Fruit flies when you're having fun. BTW, Do these genes make my ass look fat? corruptio optimi pessima
|
|
Back to top
|
|
|
The Real MC
Joined: Jun 20, 2008 Posts: 62 Location: Painted Post NY
|
|
Back to top
|
|
|
|