Embedded Lab

Khaleel123 has posted an Instructable on how he built a solar-powered FM radio/mp3 player using some leftover wood flooring, salvaged pc speakers, four ni-cad rechargeable AA batteries, and inexpensive FM Radio/mp3 player module and solar panels that he bought on ebay. The FM radio module cost him less than $3 and is capable to play mp3 audio through an SD card or USB drive.

 

Khaleel123 writes,

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.