Hi,
I'm a trombone player and I would like to add electronics to my trombone to track the slide position (in order to use those gestures to manipulate software parameters). I've come across one example of this here (see page 2): http://www.nime.org/2006/proc/nime2006_358.pdf
My intention is to use a transducer receiver pair as shown above, one stationary and one on the moving outer slide. I'm thinking of using something like these: http://www.makershed.com/product_p/jm136654.htm but the resolution needs to be better than an inch.
Ideally, there would be two circuits to avoid having a dangling cable on the outer slide: the transducer on the moving outer slide with a battery and a 555 (or whatever is small and works) to emit the pulses and the receiver on the other side plugged into an arduino (and then to pd on my laptop).
I'm fairly comfortable on the software side of things, but I'm not very experienced with hardware. I would appreciate any advice, comments, suggestions, reading list you may have for me.
Thanks!
Graynomad:
I've not use distance transducers but can't you just bounce the signal off an object on the moving slide?
For something like this, I'd use an ultrasonic transducer with a singular element for send/receive; something from Hexamite, perhaps:
...of course, you would have to build your own transmitter/receiver circuitry (an oscilloscope will be handy), but Hexamite does provide reference designs for microcontroller interfaces their products.
Graynomad:
I've not use distance transducers but can't you just bounce the signal off an object on the moving slide?
It may come to that... I guess it depends on the width of the beam. It would have to be narrow enough to avoid bouncing off the bell. I also need to figure out what to put on the slide. Weight and air resistance are issues there. Also, I wouldn't want to track objects beyond the slide, but I guess I can account for that with the software.
robtillaart:
Can you tell about the precision you need?
Most (cheaper) distance sensors I know are in the order of 0.5 - 1 cm.
What is the maximal displacement of the slider?
I think 1 cm would be fine. Slide length is roughly 62 cm and extends by about the same length. I've been looking at these sensors to use with an arduino: Ultrasonic Range Finder - XL-MaxSonar-EZ4 - SEN-09495 - SparkFun Electronics
Precision is 1 cm from 20 cm to 765 cm. So I could stick something on the end of the slide to reflect the signal back.
Only worries would be signal bouncing off the bell and what to put on the end of the slide.