This is one of the first posts! very excited from the beginning of the blog. In this post, I’ll cover the building of the solar oven I made back in 2016.
The idea is that you can use old tv screens as a giant magnifying glass, that can concentrate the sunlight to small area that is thousands of degrees.
Preview
Finding the right TV
This is the trickiest part of the project, the rest is quite straightforward. There is a wide variety of old tv’s, the one that you are looking for is a rear projection TV. Checkout google for some photos to understand how it looks. They have a large bottom section and a big screen size (at least 40 inches).
These kinds of TVs are rarely manufactured these days so you probably could find them on local secondhand websites.
Disassembly
When you disassemble the TV you will need the screen part. be sure to be careful with it because it is quite fragile. This part is could Fresnel lens, this is what concentrates the sunlight.
These TVs also have good speakers so keep them for a future project. you will also find three lenses that you can also keep for future projects.
Building the frame
This step will be different from one another according to the equipment and resources you have.
The goal is to build a frame that can hold the Fresnel Len and let it rotate to focus the sunlight.
I used a couple of wood beams that were meant to be thrown, and a broomstick.
I built a frame with an inner tunnel (a couple of mm in depth) and slide the lens inside it. I was able to make it with a table saw that we had in the place I built it.
If you want to simplify the build you can connect two pieces of wood and the lens between them (like a sandwich), just be careful not to make too much pressure on the lens. Then I connected small parts from the broomstick to the sides of the frame, to make it able to rotate.
| Frame finished | Lens frame |
|---|---|
 |
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Resources
You will find out I love YouTube as a place to research before I start a new project. Here are some links with more information about the topic
- The king of random video
- The backyard scientist video
- cool uses from greenpowerscience – has a lot of green energy solutions videos in his channel
Saftey
The heat that is generated is extremely dangerous, don’t put your hand in the concentrated spot, don’t look at it directly without sunglasses.
In the beginning, I didn’t put on sunglasses and when I stopped looking at it I started seeing black spots… as if you were looking directly into the sun.
Extra Thoughts
Searching right
When I searched the local website for old TV’s I didn’t specify "rear projection tv" but just wrote TV and guessed what would be the right one. I got 4 TVs that weren’t the right kind before I got the right TV… (and thanks to my parents for helping in carrying those TVs).
This emphasis for me a lesson that would return in every project. One of the important things is to be able to search the right terms to find the best results.
Going beyond the limits
Through the project, I felt that I don’t know if it will work, and seems quite intimidating. This is a feeling that I have a lot in my projects, but I think that when I feel it, I know this is a good project, because it is challenging, and I know I will go beyond my current limits and set new ones.
Don’t get me wrong, it is not one of the motivational slogans. sometimes projects are just too hard for me, and I end up finishing working on them without reaching the goal. This happens like 20% of the projects and this is fine because failing is part of learning and trying.
Working till sunrise
Eventually, this project had a deadline, and I came to a couple of days before the deadline with only the lens frame ready. so, I worked all night to finish the frame. This happens to me on projects without intending. I just start working, and then say to myself, one more hour of work, and after one hour I say another hour, and before I notice the sun rises.
In some projects that make me feel great and be happy that I’m so engaged in the project, and sometimes it is like an alarm for me that I’m getting too engaged and it becomes unhealthy.
This time it felt great (it was only one night 😉 )
Keep making and until the next project, roto