osc > motorised fader

hello : )

i have been using max/msp for a while and am really tempted to try out the arduino board.

i am hoping to control an audio motorised fader via osc messages. so the audio that passes through the fader can be gain controlled by the computer/msp.

i am a bit new to this area but i learn pretty fast. in my sights at the moment are :

Duemilanove Atmel Atmega 328 MCU board ALPS RSAON11M9 motorised fader

but i think i may need a few other things. : P Anyone have any ideas if there are any tutorials on this type of thing?

thanks for any help : )

You can't drive the motor in the fader directly from an Arduino pin, because Arduino pins can source mac 40mA of current most motors will draw more than that.

You need a few components to drive it, google Arduino + DC motor to find info.

The info on this thing is really sparse, the datasheets are useless It takes 10V (the motor) and the total resistance is 10KOhm I suppose the thing works as a servo. To test it you can hook it up with a 10K pot and 10V, turn the pot and see if it moves If it works this way, then you buy a digital pot that the arduino controls and use it to set the fader value.

just my 2 cents, happy info hunting

David

hi. : )

Do you mean : Does altering the 10k resistance move the position of the fader ...or does it simply alter the speed of the fader?

I really don't know, but the sliding mechanism is just a potentiometer (according to the datasheets) so in theory this is just a big (long) servo http://www.pyroelectro.com/tutorials/servo_motor/servomotor.html

How many wires are there out of this thing we know that the motors take 10V, but it could be a stepper

You could also checkif the slider takes midi commands (is there a IC onboard)

hello thanks for your reply.

here is one of these faders working with max msp. in tyhe video below, he is moving a slider up n down in the software so the music goes up and down in level and the fader follows this. this fader does not seem to be used as a normal analog fader( like an analog mixing desk) it is only used as a controller fader to control software and for the software to motorise it.

http://www.youtube.com/watch?v=Ijs6x0fJugE

looks pretty cool.

there seems to be 4 connections 2 for the motor , 2 for the touch sensitive resistance info 2 for the actual analog audio. ( if you use it as a normal resistor for an analog channel)

i see the arduino and max/msp with albeton music software. but as for the bread board on the desk? whats on that i have no idea.?

at least it seems possible. : )

here's http://www.pennyandgiles.com/Linear-Motorised-Fader-pd-113,3,,.php another motorised fader manufacturer.

Looks like it is a 10k linear pot. Depending on the operating voltage of the motor, you might adapt the board from a cheap servo to drive the motor. You might also replace it with a regular pot and turn the pot with a servo.

http://avpg2.homepage.t-online.de/PDF/RSAON11M9_Spec.PDF

ok, here is what you do

You tap into the resistor pins, send it 5V and mesure how much voltage is comming back, you map the slider down 0% and up 100% from an analog input pin. THis will be the calibration.

Active mode: Now you find a value that matches with your desired slider value Call that a setpoint

Loop till setpoint is reached: Now compare analog in == setpoint if not then pwoer motor in the direction that gives you value closer to your setpoint (e.g. 10ms left) (probably best to use PID control here)

Passive mode (reckord slider): Move slider to desired possision Push a button to reckord the analog in value, call it setpoint.

That's it Now make timer software with multiple setpoints to run through and triggers.

David

Thanks for your help. that's really kind of you.

i think if i had all the right components i could work it out. If you notice in the youtube video , the man showing the demo of the motorised slider has a few microchips and things on a breadboard and he seems to be using the same fader as the ones on ebay. so i think if i buy all this equipment, i would be missing a few parts.

i shall keep googling and post here if i find anything : ) thanks.

You only need: 1X fader,2X npn transistor (for switching 10V motor) and a powersupply (10V), (possibly a button for storing setpoints if you are making a mixer). multiply this by the number of faders (you use the same powersupply on the faders).

THe guy in the video also had some led display going so he has more components on the breadbord.

Please contact the dude yourself for confirmation.

But the motorized faders are EXPENSIVE if you have to buy them. (if using ALPS, it's the RollsRoyce off faders)

DAvid

2X npn transistor (for switching 10V motor)

How does one operate a DC motor bi directionally with only two NPN transistors? Seems an H-bridge of some type would be needed.

hello : )

i just found this Motor/Stepper/Servo Shield for Arduino kit includes h-bridges:

http://www.adafruit.com/index.php?main_page=product_info&products_id=81

Can run motors on 4.5VDC to 36VDC. But it also says 2 connections for 5V 'hobby' servos,

the motorised faders on ebay are 10v, would this work do you think?

i have sent a message of the original builder, he is also a member on this forum, here's a thread he made on the topic .

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1231041154

@ zoomkat
Yes you’re right One has to use 4 transistors for this one
You just use 2 pins on the arduino (clocwise and counterclockwise), motor connected to two loops of current (one for each direction). Each loop has 2 transistors (transformer to motor and motor to ground) switched by same pin. Easy as cake :wink:

david

hello : )

i just watched a tutorial on transistors , by using one of these and a 10v supply i will be opening and closing the circuit . so making the fader move ( on and off) at one speed only, so i would need to make max msp understand and use 'time' to get the fader to where I need it to go.

: if the fader is at the very bottom -100 and i need it to get to 0 max/msp closes the circuit for say 300 ms

:if the fader is at the very bottom -100 and i need it to get to -50 max/msp closes the circuit for aprox 150ms

max/msp can then use the feedback (touch sensitive resistor information to confirm the fader landed where it was supposed to ..if it didn't then max corrects ...and corrects ..until the fader is where is is meant to be. ( as there will be a latency on the feedback real time confirmation might not work?

on the youtube tutorial the guy was only using one transistor to power a bulb ...so i would think id need 2 ( forwards + backwards), i wonder why I would need 4?

thanks for your help

i wonder why I would need 4?

Well it's because if you don't, and make 2 loops of current to the motor, You just short the leds (you have ground and +10V connected to one pole of the motor). Hence you have to break the line to the ground too. With two breaks in the circuit you ensure that you don't get shorting to ground. But you can turn two transistors on/off from the same arduino pin, so that's not a problem.

David

[edit]H-bridge is just a chip full of transistors doing just that, so you weigh the price of 4 transistors against H-bridge http://en.wikipedia.org/wiki/H-bridge[/edit]

The below L298N h-bridge chip below may be a simple and inexpensive solution for driving your 10v motor.

http://www.pololu.com/catalog/product/924

thanks guys : )