Clever, not smart
Activity description and objectives:
The aim of this tutorial is to identify simple buttons/switches in everyday products and explain how they work. Students will break apart toys/electronics to identify the buttons/switches and discuss how they work. In groups, the students will make their own buttons to create a game controller to play old NES games online.
Other resources:
All About Circuits
Ultimarc iPac
It didn’t take long to come up with the idea to revisit the Miller Solar Engine for my first assignment for Design for GreenFab. I had actually attempted to do this project in my Sustanable Energy class at ITP last semester with not a lot of luck. In fact, everyone was having trouble with it. What is a Miller Solar Engine?
“As the solar cell charges the (4700 uF) storage capacitor, the voltage across the capacitor increases with time. Eventually it reaches the 1381′s trip point, and the 1381 applies voltage to the base of the 2N3904. Since this is an NPN transistor, it “trips” and applies current to the motor. This state of affairs will continue until the 1381 sees a voltage that looks like its trip point less 0.3 V, at which point the 2N3904 goes “quiescent,” and the solar cell resumes charging the storage capacitor.”
Got that? Can’t say it was crystal clear the first time I read it. The is the definition of the MSE posted on the Solarbotics website. Conceptually I understood it. Solar cell powers up the capacitor which at a certain point would have enough of a charge to trigger a switch to power an led, motor or whatever. At some point the power would be drained and the activity (lighting of led or moving motor) would stop. The process would repeat itself as long as there was a source of light on the solar cell giving you a pulsing effect.
In addition to the description on the Solarbotics site there was also a diagram of the circuit. I am still not the worlds best reader of circuit diagrams so it was only slightly helpful. Much more helpful was the link at the bottom of the page that led me to a Insectroides website that gave a step-by-step tutorial on how to wire the circuit on a breadboard. Incredibly clear but my one criticism was that it was only step-by-step images. No caption to walk you through what was actually going on. So what I would like to do for my first project is to take some of the technical information from the Solarbotics website and combine it with a more visual step-by-step tutorial similar to the Insectroides site. My plan is to create the equivalent of an IKEA instruction diagram with text.
