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[Reply #15 on:]

Thanks all for shearing your ideas, you are really helpfull

The main functionality I want for each faders is:
(A) when reading from software (untouched), the motorized fader must copy position of the corresponding track level in the software.
(B) when touched or moved, software level must change and record changes on the touched fader track. when it gets unused again, it should start with (A)

No pages will be used on this mixer, because it's an actual audio mixer. Motorized faders will be used only to reproduce and write track levels on the go.

Here is the article i spoke about. It is just a basic thing with some tests he done, but i thought might help( mind you , is with PIC uC's though).
http://pk2lab.blogspot.co.uk/2011/11/controle-de-fader-behringer.html

PS:Brazilian/portuguese but apart from the translator online, let me know if you need any help in case it plays up in the translation.

Thanks for the link! No trouble with portuguese, it's pretty simmilar to spanish (my natural language).

I'm getting a sample motorized fader tomorrow. I will start some testing next week with an arduino mega and I'll let you know what comes up!

[Reply #16 on:]

How are you planning on detecting when a slider is moved? Are you going to constantly poll the positions of all 24, and compare them to stored positions?

[Reply #17 on:]

Each fader has a touch sensitive track
It's the 4th pin of the fader. you can check it in the following link
https://docs.google.com/document/d/1T73_9Q8MKuLk_v-C3MBDKq-txNsqwEBvHIfMgILzMVM/edit

[Reply #18 on:]

I get that. How is your code going detect it? The Arduino only reads an analogue input when you ask it to.

[Reply #19 on:]

If you use the AD7147 chip to detect the touch, you don't have to periodically read in your Arduino loop.
The chip can set an Arduino interrupt when anything is touched or released. (page 29)
( www.analog.com/static/imported-files/data_sheets/AD7147.pdf )
It handles 13 touch contacts so you would need 2 of them.

So here's my easy, use-prebuilt chips approach.

2   AD7147  chips  for the touch control.
3   ADS8028 chips to read the fader voltages
3   AD7808 chips to provide the output control voltages
24 MC33030 chips to control the fader motors.

All the AD chips have built-in shift registers; couldn't ask for better.  Only 2 dig pins needed to shift data in or out.
Since the shift registers can chain, you might need to use up only 6 digital pins total.

The MC33030 chips provide noiseless bi-directional non-pulsed control and output driver circuits for the fader motors.

I don't know what your budget is but, to my thinking, these chips do all the hard part and do it very well.
How much do the faders themselves cost?
With these chips your software is much much simpler, and you can focus on the more fun, user interface part.

[Reply #20 on:]

Great.  Thanks alot, OP.  Now I have another project on my to-do list.   

Where are you getting these faders anyway?  And I second the question -- how much are they costing you?  If they're built worth a crap, that looks like quite the feature set.

[Reply #21 on:]

Where are you getting these faders anyway?  And I second the question -- how much are they costing you?  If they're built worth a crap, that looks like quite the feature set.

They are some faders from an old mixing console. My University proffessor got them few years ago and they are working allright. No idea about the cost, but is really hard to get this kind of components in Argentina in an affordable price.

f you use the AD7147 chip to detect the touch, you don't have to periodically read in your Arduino loop.
The chip can set an Arduino interrupt when anything is touched or released. (page 29)
( www.analog.com/static/imported-files/data_sheets/AD7147.pdf )
It handles 13 touch contacts so you would need 2 of them.

That would be ideal. I hope I can get them here in Argentina.
If I dont, maybe I could get 1/0 data from touch sensitive track and activate writing mode from code (no idea how to code it yet) in the touched track. But yes, this way means that the arduino loop must read periodically those 24 digital inputs.
I could try to buy those chips in sparkfun and ship them to argentina, but electronic importation is really hard here as well.

Thanks to you all! And sorry for any grammatical or explaining mistakes.

I will get the sample tomorrow and start to do some tests this weekend.

[Reply #22 on:]

They are some faders from an old mixing console. My University proffessor got them few years ago and they are working allright.

Just my luck.  I haven't found a place that sells motorized faders.  I guess that trend hasn't hit the DIY market yet.

And sorry for any grammatical or explaining mistakes.

I'm always amused when folks outside native English-speaking countries say this.  The wording is sometimes a little peculiar, but the text is usually spelled and grammed better than just about any American poster on the Internet.  ;-)  As if I could even write a coherent sentence in any language outside my native tongue anyway.

[Reply #23 on:]

regarding buying faders, you can buy them from any brand that uses them on their mixers/controllers ?!? depend on what you want !
Behringer probably will be the cheapest.

[Reply #24 on:]

Sorry It took me so long to come back here.

I have the fader, I attached some pictures. The fader is different from the schematics page my professor gave me. It has 1 more pin.

I can't find any schematics of this model on the web, please, if anyone finds it, that would be really helpfull.
I don't know how to find out witch signal is in each pin. As this is an old and expensive fader, I dont want to mess up and burn something. Any suggestions on this?

This far, I reached to move the servo motor one way with a 9v battery. I will add an H-bridge to make it bi-directional.

Next steps (after knowing each pin function)
- Controlling fader servo from Arduino PWM output bi-directionally
- Reading Analog input data from position fader
- Reading Touch sensitive track

After this, I will start messing with software and midi or OSC protocols.

Cya!

[Reply #25 on:]

http://www.faders.com/
Go straight to the brand and ask them. Im sure they will be willing to help.

[Reply #26 on:]

Seems they were from a top console called API ( a very valued brand mind) Ill get in contacrt with an expert on them.

[Reply #27 on:]

Thanks iyahdub!!
I just sent them an e-mail asking them for a datasheet or at least a pinout connection explaining.

Yesterday I made the motor run one way using an Arduino mega PWM output and controlling PWM pulses with a rotary potentiometer.
Strange thing happened, when the PWM output value was less than 255, a high frequency sound was made by the servo while it was running in a slower velocity.
Could this sound has something to do with a non-filered output? Or this could mean that this servo wants only high velocity pulses?
I will try to get a MC33030 chip as soon as possible so I can control the servo both ways with the rotary potentiometer.

[Reply #28 on:]

ive asked to some people who actually work and have much more experience with those given consoles.
One of them said he had no experience with the specific ones, so im waiting for the others.
If i can, ill help  !

[Reply #29 on:]

Mytx,
Why not try bi-directional direct from the ARduino using 2 digital pins.  No PWM.
Two pins, one to each wire side of the motor.   Hi, Lo  moves one way;  Lo, Hi moves the other way.
No pulsing, no PWM.  I don't think the fader motor was designed for that. Full DC only. Instant reversing.
Pulsing works well on most dc motors because of the flywheel effect.  The momentum of the heavy shaft, motor armature, or even flywheel smooths out any effect of the pulsing.  These faders have none of those.  They're designed to immediately stop when current stops.
Some lower frequency component of the PWM frequency resonates with the mechanics and causes the whine.

Note that though the ARduino pins can source or sink current, many of the digital pin expansion chips will only sink current (to ground).