Making Joule Thief lanterns for a better world
My dear colleague Tracey Winey (you can find her on Twitter at @winey02 ) introduced me to the idea of philanthropic engineering – that students can make projects in class that can be useful in real-life for a good cause. Years ago, she and some other educator colleagues came up with the idea that kids could genuinely tackle light poverty – the lack of artificial light sources after darkness falls. In areas where electricity isn’t available or isn’t reliable, a nice light source can make a huge difference when it comes to studying, cooking, doing chores or staying safe. Our school and others around the world have already sent dozens of little lanterns to people in Guatemala, Honduras, Nicaragua, Uganda and other locations. You can find out more about the effort at http://e-b.io
This is normally an after-school program and my after-school hours are really limited with a busy family. This year I am getting my whole electronics class involved by having them create lanterns for Engineering Brightness. After some tweaking of the process this is where I am with it now.
- I provide the electrical design and all of the parts, and the students pay a small class fee to cover costs.
- Students solder the circuit together by following instructions I provide.
- Students design some kind of case or enclosure for the lantern, by prototyping with cardboard and other household materials.
- We will present and share the lanterns with their enclosures, and 3-D print a handful of the best designs.
- As a class we’ll assemble the final projects and then put them in a box with some cards and photos. We will send them to either Liberia or Guatemala where Tracey has some contacts through her church.
I will share plans on how to make these if you’d like to have your class try it out as well. After we have a couple of enclosure designs, I can also share the 3-D models of those so you can print them and assemble the whole thing.
Before I get to the how-to’s, of course the big question here is what are we trying to teach the students? What do I hope they learn and how will I know they have learned it?
We’re working a little outside Colorado’s state science standards, but I don’t think every worthwhile learning experience has to be linked to standards. I also believe it’s OK if every kid’s learning is different. Here are some of the areas in which I want to see growth from the kids.
- Understand that electrical circuits require a closed path, a load, and a voltage source, and identifying those in a real-life circuit.
- Identify some basic electrical components, what they do and how they work.
- After working with a design, identify ways it can be improved such as cost, size, durability and quality. Know what a tradeoff is and make smart tradeoffs when improving a design.
- Consider a purpose of a product and improve it for that purpose.
- Identify common electrical problems or mistakes and describe how to fix them.
- Solder safely. Produce work that improves in quality over time.
- Make something that will be meaningful to another person.
I based my little lantern design on a “Joule Thief”. Normally, a white LED takes around 3 volts to light up brightly – so you need two or three AA batteries for the purpose. Three are better than two, because once the batteries drain even a little bit, two won’t work well anymore. Rechargeable batteries are important because it is difficult to replace batteries in light-poor areas. The Joule Thief conserves cost and battery life by using a transistor and a ferrite toroid to make a single 1.2 volt rechargeable battery create a pulsing voltage that is enough to light an LED. It does this by making a magnetic field oscillate and it adds to the battery voltage. I go through some basic circuitry lessons with the kids, and we learn about LED’s and resistors, series and parallel circuits and what they do, and then we watch the joule thief video and compare/contrast it to a plain DC parallel circuit.
The students learn how to solder first by watching videos, and we take a soldering safety quiz before they are allowed to solder. Then students make their project bags and start assembling lanterns. I have had parent volunteers come in to help supervise the soldering and that has been a huge help.
I made this YouTube tutorial that shows you how to assemble the Joule Thief project. The students watch this video and pause it in spots to assemble their lanterns.
In the video description, I’ve included a parts list and the instructions for making the circuit boards. I’ll also include it here. You just have to order some cheap electronics online, like wire, transistors, solar panels and ferrite toroids. The lanterns take one of everything, execpt LED’s. I used ten LED’s for each lantern. It’s all in this spreadsheet. You can make them for around $5 each if you shop around a little. I use eBay, Jameco and Amazon for my purchasing.
The circuit boards are really fun to make. A couple of years ago, one of my former students came to visit me and showed me some custom circuit boards he created. He taught me how to design and upload my own… sometimes you’re the student, sometimes the teacher. The basic process is:
- You lay out all of your components and the wiring using a program called Fritzing.
- You export your Fritzing circuit to Gerber format. This gives you a bunch of files in a folder. If you want to use mine, you can download them here. GERBER FILES
- You zip the folder using something like WinZip.
- Go to Seeed studio at http://seeedstudio.com/
- Select their Fusion PCB service.
- Upload your zipped Gerber folder. You can use their Gerber Viewer to see the circuit board and make sure it looks OK.
- Choose your options. I prefer a 2-layer board because the students get a solder pad on the top and bottom of the circuit board. My board’s measurements are 42.8mm*67.2mm and sometimes it doesn’t update correctly.
- Decide how many you want. Place the order and it will be shipped to you!
Some of the first students finished soldering their circuits after about 3 classes, and they’re making little enclosures as well. I’m asking them to prototype enclosures using household items – and we’ll 3-D print the best ones. Here are some of the ideas so far.
I really love literal “light bulb moments” when the students finish soldering, flip the switch and the lights come on. It makes me proud every time I finish one, and I’ve done this a few times by now. It’s exciting for a first-timer.
We’ve watched some videos about Liberia and will be learning about Guatemala as well. I want the kids to start to get to know the people who will be receiving their little solar lights. Fingers crossed for a successful finish to the lanterns, and I really think if nothing else, they feel more competent and confident when it comes to working with circuits.