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[on:]

Hi, I was wondering if anyone has had any luck hooking up a VCA or VCDA crossfader to arduino?  The particular crossfader I have is a spare from my Numark PPD01 mixer (http://www.numark.com/ppd01). The connector has 6 pins on it. I can't seem to find any datasheets on it to find out which pin does what, so I was wondering if anyone had any experience with this sort of thing. Thanks so much in advance!

P.S. Here are a few images of the crossfader (if it helps any):

[Reply #1 on:]

Hmm  lets think...


Crossfader must act like a voltage divider for 2 signals.  Therefore, it acts like 2 potentiometers so you have 6 pins.  ANALOGREAD would work just fine... depending of course  on what you want to do with it.

[Reply #2 on:]

Basically, I wanted to use it as a potentiometer.  I'm playing around building an auduino and thought it might be fun to add a crossfader to control either the notes or the volume of the output. I tried hooking it up and was able to read data, but the data that was coming in didn't make sense to me.  It would read 1023 most of the time, but when I moved the crossfader it would jump to 463, 864, stuff like that, and then sometimes return to 1023.   The numbers were not in sequential order like I had hoped they would be.  I'm just assuming I'm missing something due to my ignorance.  

Assuming the ground wire is coming in through the case, and there are 3 wires per "potentiometer" in the fader, 1 would go to the 5V, one would go to the Analog I/O, and where would the 3rd go? Or would the 3rd go to another Analog I/O?

Thanks for you help!  

[Reply #3 on:]

Hopefully you have a OHMmeter to check the pins.  The pin that "varies" should be attached to an Arduino analog pin through a 220Ohm resistor.

You can get away with attaching the other two pins that respond to the same pot to the +5V feed and to ground (GND).  To be safe, maybe start by using a 1K resistor on each of these legs between the POT and power and ground.

Remember... you should never forget about the importance of GND...

[Reply #4 on:]

Thanks!  You've been super helpful.  I'll play around with it and see if I can get it to work.  I'll post my results when I can come to a conclusion. ;D

[Reply #5 on:]

Awesome!  I got it to work! You were correct.  The only thing I notice that is strange is sometimes I'll get values like this when I output what I'm reading from it:

61
61
61
60
60
6
60
60

Sometimes it shows a 6 instead of a 60, or a 8 instead of an 80.  Other than that it's working beautifully!

Thanks again so much!

[Reply #6 on:]

I haven't thought about it much, but...

Slide pots, in my experience, tend to get "dirty".  It's the nature of the physical design.  This might create some not-so-perfect spots on the resistor material.  You just want to send the data received through some kind of normalization routine.

IE; You may want to toss our values greater than 15 (delta X) from last value.

[Reply #7 on:]

That makes sense.  Thanks!  I'll do that.