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!
Step 1: What You Need
- 1 - 2N3904 Transistor (we buy ours from Jameco)
- 1 - 2N3906 Transistor (again, from Jameco)
- 1 - 0.1μf Ceramic Capacitor (once again, Jameco)
- 1 - Photocell (yup - Jameco)
- 1 - 40Ω 0.2W Speaker (this is from All Electronics)
- 2 - CR2032 Coin Battery (from Batteries and Butter)
- 36 inches – Copper tape (you can get this from craft stores that sell stained glass supplies. Since we need so much, we purchased ours through Amazon)
- 1 – Phototheramin Template (see attached file below - the project can be done without the template, but it helps, especially if you aren't familiar with circuits)
- 1 – 5”x7” Chipboard (cereal box cardboard will work, but we purchase ours in bulk from U-Line)
- 1 – 1” Double-sided foam tape (for most people, just pick up a roll. We purchase individual squares from U-Line to help reduce waste
- Masking Tape
- Hole Punch
Step 2: The Video
Step 3: Step 1 - Mounting the Template
Step 4: Step 2 - Adding Battery Flap and Holes
Step 5: Step 3 - Laying Down the Path
Step 6: Step 4 - Adding the Transistors
Step 7: Step 5 - Add the Capacitor and Photocell
Step 8: Step 6 - Add the Speaker
Step 9: Step 7 - Power!
Step 10: To Use...
A fairly simple explanation we use with the kids who visit the Museum is that this is an example of an electrical circuit where electricity flows from the batteries, through the circuit, and back to the batteries. The speaker plays a tone created by the transistors and capacitor. This tone is controlled by the photocell, which acts as a sensor. The more light the photocell receives, the higher the tone and the less light, the lower the tone. This is also a great project to discuss how some electrical components (like transistors) can control how the electricity flows through a circuit, how some (capacitors) store up electrical energy and release it, and how some circuits have control mechanisms - sensors (in this case the photocell) that controls how the circuit acts.