The Appropriate Technology Collaborative

Carlmont HS "Blue Light"

This year students in Casey O’Hara’s Green Technology Design class took on an ATC World Challenge Design – to design a $2.00 light fixture for use in less economically developed countries.

The class made design presentations on YouTube:

Here is the program statement they wrote -

In many areas of the world, people do not have easy access to many of
the resources we take for granted every day. Things as simple as
electric light are difficult to obtain, without access to a reliable
power grid.

In hopes to solve this problem, our class decided to design and create
inexpensive solar-powered LED light fixtures.  The Engineering & Green
Technology course at Carlmont High School, in Belmont California,
learns about different engineering techniques. Teaming with the
Appropriate Technology Collaborative, our Engineering & Green
Technology classes found ways to create electric light fixtures for
less than $2. We used common materials, such as recycled bottles, and
efficient LEDs as a light source in designing our light fixtures.

We started by figuring out our objectives we wanted to achieve, and
the constraints within which we had to work. The final products would
need to be produced for less than $2 (excluding the LED), and
aesthetically pleasing to appeal to the customers, so they would be
proud to use it in their homes.  These light fixtures also needed to
be low power, so they could last longer using rechargeable batteries
charged by solar panels.  We were provided with a 5V cell phone
charger as a power supply and a 1W white LED for light, the rest was
up to us.

The class divided into groups, all with the same purpose: creating a
functional and efficient light.  We first learned how to include an
LED in a circuit.  The circuit includes the LED, a resistor to limit
the current, and a power source.  Each group used different materials
and made lights that could be used for a specific function. Some
groups chose to design lights for reading, focusing the light for a
brighter beam, while others chose to design general-purpose lighting
over a larger area, for use while cooking, dining, or performing
simple work.

To make sure our lights achieved their purpose, we learned how to
measure light output, took polls to gather additional advice, and
continually revised our prototypes.  Based on research we found how
much light is needed for reading (100 lux minimum) and general purpose
(50 lux, similar to a family room, was our target).  We tested our
lights to make sure they provided adequate light to meet our goals.

After groups presented their designs to the class, we selected the
most promising designs to send to the Appropriate Technology
Collaborative for further review.  We hope that our designs will make
it easier for people to work in the evenings, and for children to
study for school, helping to improve their overall standard of living
for families living in difficult circumstances around the world.