Vinyl player/turning table

We have the idea of creating ??a big "vinyl player". The idea for the concept comes from an barrel organ (http://en.wikipedia.org/wiki/Barrel_organ '). The idea is that we have a circular track we'll lasercut with increase and decrease levels. On the track we want to put arduino. This rotates about the circular track. The arduino measures the increase and the decrease of the track and sends that value. The track consists of 4 different lines. If an increase is observed, it must play musical note ('processing'). So we want to play a full track consisting of 4 musical notes. The song plays continuously , so it is circular. For the duration of 1 song is 1 rotation.

Now our question to you: How do we measure that increase and decrease on the track? So we get a clear signal whether a note should be played or not.

which sensor can we use for it? together with any code?

  • http://www.youtube.com/watch?v=JMnGKg9faug This is actually our concept, but we want to recreate it analog. The blocks that appear are our increase and decrease. And that should arduino notice. This signal must be transmitted through processing and plays a musical note .

our question to you: How do we measure that increase and decrease on the track?

Use a reflective opto sensor.

Grumpy_Mike:

our question to you: How do we measure that increase and decrease on the track?

Use a reflective opto sensor.

Ok thanks for this info. But our track will consist of wood because we're lasercutting it. Do you suggest that we use reflective material on the increase so the values are more clear or how do you suggest that we use this sensor? We probably need four of those for the four different tracks, right?

Thanks!

Another option - and I have no idea whether this will be easier or harder - would be to use some sort of pin-based sensor that can drop into the lows and be lifted up by the highs. I guess this is the sort of approach you'd have had to use before electronics were available. If you managed to arrange the pin to make or break a contact as it moved up and down, that would give you your digital input.

(I'm envisaging a pin that is sprung against a stop and pushed away from it by the 'high' in your track, no complex pivoting/sliding parts needed, just a small piece of bent wire.)

Do you suggest that we use reflective material on the increase

Yes a simple solution would be to paint it white before you let the laser at it. However you might get enough reflection without any surface preparation. Do some experiments first so you know how deep to cut.

We probably need four of those for the four different tracks, right

Yes you only get one signal from one sensor.

Something like this:- http://uk.rs-online.com/web/p/reflective-optical-sensors/1714918/ Only that is about twice as expensive as it should be.