Create a functional circuit diagram that makes an instrument controlled by brightness of light!

This is one of the 48 projects for our Instructables: Made In Your Mind (IMIYM) exhibition at the Children’s Museum of Houston showing from May 26, 2012 - November 4, 2012. Produced in partnership with Instructables, IMIYM is an exhibit where families work together to build different fun, toy-like projects that help construct knowledge and skills related to science, technology, engineering, and mathematics while instilling a “do-it-yourself” attitude in kids so they feel empowered to explore, tinker, and try to make things themselves. To learn more, check out the article here.

For this project, we were inspired by the How to Make an Easy Phototheramin Instructable created by TigrisLi (which, as I discovered is based on the Audible Light Probe by Forrest M. Mims III of Radio Shack books fame) , but there may be others on Instructables that are also similar. Often, the materials and process for building our projects are designed for use with a large number of visitors (we see over 800,000 annually) and the need to ensure safety in a mostly non-facilitated environment (in other words, no soldering). So, yes, many of these projects have room for improvement in both materials and methodology, which is PRECISELY what we want to encourage the kids to do. So please do share your ideas for improvement and modifications!

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Would a piezo buzzer work in place of the speaker? Thank you in advance...

jim_20001 year ago
I couldn't get this working with the copper tape either. Has anyone figured out how to make this circuit without solder?
Sorry you're having problems. Three possible issues and solutions:
1. We've discovered is that sometimes people get the transistors in the wrong place or backwards. Check to make sure they are put in correctly.
2. Sometimes leads are corroded or otherwise don't have good conductivity. Sand them gently to remove any corrosion and make sure to tape them on tight.
3. Some tape is conductive on both sides while others are conductive on one side (sadly, no packaging to tell us). So, where the tape must overlap to create a completed circuit, it doesn't work (I'm hoping that makes sense). My suggestion to solve this is to use wire to connect separate strips of tape instead of overlapping strips of tape.

I hope one of these solutions works out!

Actually the 3904 transistor on your build sheet is in backwards. The circuit is a type of relaxation oscillator, the collector of the 3904 should be connected to the base of the 3906. I tried it both ways and it is much louder if you flip the 3904 180 degrees, pin 3 to middle pin of 3906 and pin 1 to ground.

cds333em1 year ago
I REALLY wanted this to work! Auugh, I'm sitting here with my attempt at this project and it is not working. Would love to do it with Middle School students, but if I can't do it, I can't expect a classroom to do it.
Would love to see how you do this project with museum participants.
workwood2 years ago
Super instructable!

One question though: can you give me more specifics about the photocell?

I can only find really expensive ones online.
And I don't know much about electronics..
So can you help me out?!
beatmakers2 years ago
Great Instructable. Well done mate.