Boarduino powered laser harp now working!

[shobley]

Just a quick 'thanks' for the help with getting this project off the ground...

Quick demo here:
http://www.youtube.com/watch?v=sLVXmsbVwUs

Steve

[ih8gates]

that's a beautiful thing. nice.

[darus67]

Very Cool

[adafruit]

that is so awesome. SPACEMUSIK!

do you think you could post up how you did it? i get laser-harp-request emails every month or so

[TomLackamp]

Wow! Just stunning, in both concept and execution.

Amazing!

Tom

[shobley]

I first saw the laser harp during the Jean Michel-Jarre concert 'Rendezvous Houston' in 1985. Ever since then I've told myself that I would build a laser harp, and it would be *just* like the one I saw - it would open and close and be frameless (ie no sensors above the player).

For a long time I was convinced it was impossible, the sensors I used (CDS cells, and photodiodes) just weren't *sensitive* enough, giving at best a 12" range.

Then I made 2 errors in my detector circuit - I wired one Op-amp input to 5v not gnd, and forgot to connect the other op-amps input to anything. Then it started to work incredibly well - detecting pulses over a 20' range. (I still don't know 100% how it works)

I've been meaning to put together a website. I've had so many emails lately that I think I'll start tonight.

I need to make a better movie, I have opening and closing sound effects that *should* have been loaded into a sampler. The noises you hear when the beam opens/closes are not the right ones.

I'll shoot the movie tonight and start the web page.

Steve

[shobley]

Here's a couple of pics I took.

[shobley]

New movie - actually playing a tune this time...

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

and "under the hood"

[adafruit]

out of curiosity, why a scanner instead of a prism?
(im so nosy )

[darus67]

A prism wouldn't get you individual beams, would it?

[adafruit]

i such at photonics, i mean a beamsplitter

http://cgi.ebay.com/CUBE-BEAM-SPLITTER- ... dZViewItem

you can cut a piece of plastic to split a beam up.
seem kinda pricey tho, maybe its just cheaper to use a scanner

[shobley]

You can use a diffraction grating to create beams, but the trick to this type of reflective sensing harp is that the 10 beams are really only one beam, but in one of 10 locations at different times.

So...

Time of returned pulse => beam # broken => MIDI note to play

If we had "always on" beams then this wouldn't work, and you would need 1 sensor per beam.

Also you can do the opening/closing animation with a scanner.

Steve

[shobley]

I'm interested in the new Boarduino with USB - this would be a useful "drop in" (I hope) addition to my harp.

Any idea on price point / availability?

[adafruit]

oh, cool...i got it. i assumed there were different sensors for each beam
i will await the documentation

[darus67]

The animation is a nice touch.

Is it simply a digital on/off signal for each broken beam, or does the height
of your hand have any effect on the note? (amplitude, duration, etc)