IDEAS For Us | September 2, 2014

Eco-inventions: Making a solar cell phone charger

Hey everyone,

In the Eco-invention series, I will document my electronics endeavors that focus on sustainability. With electronics, the most effective thing we can do is to recycle our electronics (at your local Best Buy, etc.). If we have some knowledge, we can also make our own recycled inventions. Let’s make a small solar charger today…

Solar_invention1 Solar_invention7

This is what we will be using. We have a discarded wall charger, discarded solar panel from a broken nightlight, a USB chord, and a 5-volt regulator from a toy (the infamous LM7805 >:D ). All of these components were salvaged instead of being thrown away.

Fortunately, this is a simple build. The picture above is a diagram for this invention. The red-ish colored lines are positive and the black lines are negative (aka “ground”). What happens here is that the solar panel gives energy to the regular. The regulator takes whatever energy the solar panel outputs (up to 10 volts!) and makes sure that only 5 volts is outputted (on the orange line). Thus, the USB gets only 5 volts, as it should, and any device can suck up the full 25 mA force of this solar panel.

Here is everything soldered up. I decided to put a capacitor to smooth the solar panel output, but it honestly is not needed. All I need to do is solder the USB port and tape it together.

I forgot which USB pins were meant for power, so I did a Google search to solder the negative and positive wires correctly. As you see here, I used velcro for the electrical components. This is because it was the stickiest thing I had at the moment. I used electrical tape for the dangling wires.

Here is the back-view of the finished product.



It actually works when clouds fly over as well! This ultimately is a small solar panel, so I don’t expect it to charge fast. It will be useful when out in the woods, though.