Vol. 15: Laser Harp

Play strings of light, using laser pointers, rangefinders, photocells, and Arduino.

Photos by Jacques De Selliers, Stephen Hobley

+ Downloads & Extras:

Analog multiplexor:

AIN Kit (32 analog inputs) from http://www.avishowtech.com/mbhp/mbhp_ainR4.html

This uses 4 standard 4051 analog multiplex chips – documentation is available on the internet on how to use the control lines to connect to each of the 32 inputs.
[www.arduino.cc/playground/Learning/4051]
[http://little-scale.blogspot.com/2007/06/arduino-midi-out-example.html]

Note: With some clever programming you can use just the analog multuplexor to drive the laser harp – connect the outputs of the photocell array directly into the inputs of this board, then you can detect if a beam is broken in software inside the Arduino.

Digital Multiplexor:

DIN Kit (32 Inputs) from http://www.avishowtech.com/mbhp/mbhp_dinR5.html

This kit uses the 74HC165 chips these take the parallel input lines and create a serial stream, you can chain these modules together and have as many inputs as you need. Documentation is available online - the Arduino playground is a good place to start.
[www.arduino.cc/playground]

-=-=-

More than anything this project has been a testament to the collaborative power of the Internet. I could not have done any of this without the help of many people – who were good enough to answer all the questions I posted on a variety of forums. I'd like to take this opportunity to pass on my gratitude - please keep up the good work! If you want to tackle a full sized scanning laser harp – then more information can be found on my website www.stephenhobley.com.

� MAKE: NOISE — Discuss this article

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Showing messages 1 through 5 of 5.

laser pointers
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Could any one tell me which laser pointers I need to get for this project? since it is not specified in the article, I bought some simple ones with <1mW output, but the beam is not visible. I have noticed that laser pointers go up to <5mW output, but I am not sure if their beam would be visible. Can someone tell me?
thanx a lot in advance
Posted by lolarainbow on November 02, 2009 at 07:10:30 Pacific Time

share your work
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Has anyone out there actually built one of these harps? and if so does it work properly? I get the idea I may have used the wrong type of parts. I would love to interface with someone who has a working harp, using the plans in this article.
Posted by looking up on September 30, 2009 at 13:50:12 Pacific Time

harp vs theremin
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Is there suppose to be a pitch change for the harp notes, like in the theremin note. I have constructed the theremin, then the harp, but I don't seem to get the pitch and bend on the harp. I don't even get it on the first note, which is what I used for the Theremin. Help?
Posted by looking up on September 12, 2009 at 13:54:36 Pacific Time

laser harp code
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I'm surprised to see only one comment on the laser harp project, but after overcomming many hurdles I have finally completed the project, only to find that it doesn't work. I cannot seem to get the notes to "bend" as I move my hand up and down. When the arduino is programed for the Theremin, it works great, when I reprogram it for the harp, I can get the note on, and off, but there is no variation to the note as I go up or down. I have read the program and have noted that I may have to fine tune it, but I know nothing about programming the arduino, or anything else for that matter, so I am at a loss. If anyone else has experienced this it would be nice to know.Guess I'll start learning how to program the Arduino.
Posted by looking up on June 07, 2009 at 19:23:10 Pacific Time

how about power source for LM324??
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Hi!
Now I'm making the coolest laser harp.
But I have one question!!

How about power source for LM324?
Should I prepare another power source?
There is no datail about power source in the book "MAKE".

please advice me about specification for AC Adapter.

Posted by fgg0202 on March 09, 2009 at 15:38:48 Pacific Time

Showing messages 1 through 5 of 5.

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