Solar Powered Radio With Bluetooth + MP3

The objective for this project was to create something useful from odds and ends around the house. Through this project I found new use for some leftover wood flooring, salvaged pc speakers, and also some ni-cad rechargeable AA batteries. I did have to order the Radio Module and solar cells which cost me under $5 shipped on ebay. This radio module came with a remote and is loaded with features, its well worth the around $2.50 I spent on it. Along with the integrated FM tuner it also has a Bluetooth receiver and can play mp3's loaded onto an sd card or usb drive.

Step 1: Layout and Design

In my personal experience all projects seem to start out with a sketch on a clip board or note pad. Fine tuning the layout, parts involved, along with materials available to me. In this case I knew the rough dimensions of the extra wood flooring panels, together with the rough width and height required for the layout I had in mind.

Step 2: Prepare the Wood / Construct Enclosure

In order to make the wood flooring usable, I first had to rip the tongue and groove off of it using my table saw. Then I proceeded to cut the wood into the desired dimensions to form a box with mitered joints that has a top and bottom. I then used a pencil to layout all the openings that needed to be created on the front. Using both a hole saw kit and hand saw I was able to make rough holes, that were then sanded smooth. Initially I wasn't going to inlay the solar cells but decided to do so once I saw how far they stuck out on top. For the inlay I used a router with a jig then to square up the corners I used a chisel. Once all the cuts had been made I used wood glue to glue the whole thing together leaving the bottom unglued. I glued some scrap wood on the inside of the left and right side to later be used as a place to screw the bottom into. I had taken more pictures but my camera was unable to save them correctly, so they ended up corrupted.

Step 3: Install the Electronics

There are various radio modules out there on ebay, each one can be slightly different. The one I used has an operating voltage range between 5-12 and it is 4 ohm stable @ 3 watts rms x2. So knowing this its safe to use the following combination of components for the power source. Four rechargeable AA batteries in series which can be charged up to 5.8 volts but in our case will only get as high as 5.3 volts. Along with two 6 volt solar cells in parallel with a diode that drops the voltage .7v the total output of the solar cells is 5.3 volts at 300 ma. The diode is necessary to protect the cells from the power stored in the battery. The speakers are 4 ohms @ 10 watts so those are exactly within the recommended range for this type of module. The module did not come with any wires or antenna soldered to it, but was clearly marked and easy to solder to. Also the batteries had to be soldered to each other, as long as you scuff up the ends they can be soldered easily too. I just soldered on a around a foot of wire for the antenna then coiled it and hot glued it down. Hot glue was also used to secure the solar cells, speakers, and battery just because it was quick and easy to do it that way.