Revisiting Gravity Lights
If you have been following our posts since January, you probably know already that earlier this year we designed an environmental engineering curriculum on Gravity Lights that we co-taught to students with our partner teachers in Term 1. In this unit, teachers taught their students how to apply the knowledge of pulley systems and gears to design a technology of Gravity Lights and promote it to their communities to reduce on excessive use of paraffin candles for lighting in rural Uganda. Paraffin candles are a health hazard when used indoors excessively and often cause house fires that injure family members, most often small children. Gravity Lights are a great way to have safe and environmentally-friendly lighting in the home! Catch the highlights from the Term 1 Gravity Lights lessons in our Term 1 impact report here.
Issues with the first Gravity Lights prototype
Now we are taking the experiments up a notch! As true engineers, both teachers and students have been requesting advice on how to improve their Gravity Lights so that they work better and for a longer period of time. In response to their feedback, we worked with local techies to try out different materials for the gears and dynamos. The gears in the first prototype were wooden and, when machined, the gear teeth were not a standard size. The inconsistencies in gear tooth size often led to jammed gears that stopped turning and then the light would go out. In addition to the wooden gear issue, the dynamos in the first prototype were too weak to power anything beyond a small LED…these were the best dynamos that our Yiya team could source in Kampala, the capital of Uganda, but they still were not strong enough to power a light bright enough to replace a candle.
A resourceful solution!
But after much experimenting, our techie saviors came up with an ingenious idea! They took apart old printers and salvaged their internal gears and pulleys, as well as their super powerful yet small motors. Printers have motors that can give out up to 12 volts, enough voltage to power even two 0.5 watt solar bulbs! They also contain so many gears of different sizes. Now, our newest prototype uses both the gears and motors from old broken printers to supercharge the Gravity Light! This prototype can light a brighter bulb (in fact, TWO brighter bulbs) and also can run for much longer. In addition, the recycled gears turn more smoothly and don’t jam the way the wooden gears used to.
Training teachers to upcycle the printers
In our recent workshop with partner teachers in Lira District, we trained teachers to salvage gears, pulleys, and motors from dead printers to super charge their own Gravity Lights prototypes back at school. Teachers were absolutely thrilled! They are so excited to get back into the classroom in Term 3 and let students experiment to improve their prototypes with these new (old!) materials.
Teachers left the workshop fully ably to extract these resources from dead printers, as well as to assemble them between two pieces of wood in a required velocity ratio, to create Gravity Lights. We also distributed 2-3 used printers per school as a start (students can find more if needed from local printing centers in Lira Town).
Benefits of this upcycling approach
This is a double win for our teachers and for the environment! In Uganda, the waste management system is essentially nonexistent and there are no good options for recycling electronics. Therefore, we are excited to find afterlife uses for these old printers! This is even better for our teachers and students, since printing centers are often overflowing with these dead printers and the printing center is only too happy to get rid of a few printers for free!
At the workshop, teachers noted that it is much better to use motors and gears from printers, because (1) the motors can power two bulbs, and (2) the gears have well-crafted teeth that can easily drive each other unlike the gears cut from wood that they used in Term 1.
The gears are in motion!
See here our unfinished sample of the prototype of Gravity Lights that uses materials from old printers. We can’t share the finished Gravity Light because it is an engineering challenge for students in our partner schools, who will be sharing their improved prototypes at the Annual Yiya Interschool Engineering Competition & Community Showcase at St Katherine Secondary School in Lira on October 6th!
Come join us for this exciting event and see the students’ improved Gravity Lights in person!