When faced with a situation where urban survival is required it is important to take initiative and be resourceful. When foraging for practical parts consider what is visibly out in the open. There are a number of gardens in and around your neighborhood hosting a device that will provide you with an endless supply of usable energy i.e solar powered garden L.E.D. lights. The solar panel used on these are inexpensive and can be coupled with many devices to provide a constant supply of energy and in this case I refer to a portable radio running off of AA batteries.
Most of us have an old radio in storage so I based the price on the cost of purchasing or acquiring a solar powered garden light. There are garden lights all around us in abundance possibly inoperable due to terminal corrosion but the solar panel on top most often works perfectly.
I have been testing my solar powered radio by leaving it on for twelve hours a day for four weeks straight and it has not failed me to date even with the volume level set on high. My radio sits indoors on a windowsill but I could also leave it outside in the sun to recharge the batteries.
- Portable AM/FM radio using 2AA or 3AA batteries
- Soldering iron with solder and red and black cable 6″ lengths
- BAT43 Schottky diode or Silicone IN4001
- One 4 or 4.5v 80 mA solar panel, pried off of a Garden Solar Light
- 5. 2 or 3 NiMh rechargeable batteries minimum capacity 800 mAh per battery
- Optional – an adhesive foam strip and heat shrink sleeving
This radio project can be completed in about 2 hours.
Remove the Solar Panel
It is important that you find a solar panel with eight solar strips running the entire width of the panel. There are cheaper models where the panels have only four strips or are divided down. The full eight strips are required to provide the proper 4.5v 80 mA output.
Detach the metal rim and the clear plastic lens from the garden light (should be easy to remove). With a screwdriver, carefully pry the panel away from the body of the light. It is most likely adhered with glue. Then cut the connector wire and remove the panel completely.
Some radios have a power input socket for mains adapters, mine did but it was an odd size (Sony). This option makes connecting the panel more easy, just connect a suitable jack plug to the solar panel (using a blocking diode) and that’s it, check polarity is correct!
Connect the Radio
Some radios have a power input socket mine did but it was an odd size. When you can this option provides an easy connection to the panel. I chose to hard wire my solar radio so here follows my approach:
- Eliminate the rear panel of radio and with the battery’s in situ, using a multi-meter, identify the positive and negative connections for power. Make sure the multi-meter doesn’t reveal a negative if so you have the positive and negative probes the wrong way around.
- Solder the 6″ lengths of red to the positive terminal and black to neutral terminal.
- Drill a hole in the plastic large enough to allow the two wires to exit the back panel when reassembled.
Solar Panel Blocking Diode
Next solder a BAT43 or IN4100 blocking diode to the positive terminal on the solar panel. The BAT43 Schottky type diode is better because it has a less of a loss in voltage loss, which is important if you are charging 3 battery’s. The diode evades any reverse current from the battery when there is little light.
Make sure the white or black band sits away from the solar panel. You can verify if you have connected the diode properly by using a multi-meter set to volts to observe if there is output in bright light. If not change the diodes connection.
Position the solar panel centrally onto the radio with a piece of double-sided foam adhesive tape. Some radios may have a stand ideal for mounting a panel, if not you can easily position the panel on the top of the radio. Use the heat shrink tubing to cover any bare joints after you solder up the positive and negative wires from the radio to the solar panel.
The project is complete and for me it has worked well. I used to work at my computer listening to a stand-alone stereo using over 40 watts of power. This radio can last for a long time and it costs nothing to operate. Perfect for urban survival.