Well, probably such situations are not that common, unless you love hiking in unknown forests and part of your adventure is getting lost at night, or you live in a place where power cuts never occur, hence you are never prepared for such incidents. But Instructables member ASCAS came up with a small device that can provide light only by adding water to it, and help you find your way to salvation no matter what the situation is.
The miracle self-made super green device is a flashlight, which is powered entirely by water. Not only it can never run out of battery, simply because water is everywhere, but it also does not pollute the environment with toxic chemicals associated with conventional energy storage devices. If tap water is added, the little gadget works for 30 minutes, while using salty water makes your surroundings brighter for entire 2 hours. What is more, the type of battery it uses, also known as “Galvanic Cell” can be fitted in calculators and clocks, all you need is to just add water, which does the function of the electrolyte.
If you want to make one of these beauties yourself, and why wouldn’t you really, you need: PVC Pipe 4″ Long, PVC Coupling 3/4″ to 1″, Recycled 3xLED Torch, Toroidal Core/ Bead, 2N3904 Gen. Purpose NPN Transistor, 1K Ohm Resistor (1/4w), Cooper and Zinc Strip, Magnet or Copper Wire, 5 Sheets Of Toilet Paper, 2×2″ Sheet of Acetate, Leatherman MultiTool, Soldering Iron, Hot GlueGun, Teflon Tape, Super Glue.
Once you have acquired all of the above, just follow the next five simple steps, and you will have your flashlight ready to use.
This is essentially the power cell, which is made of the two metal strips- the copper and the zinc ones, which serve as an anode and a cathode. Take the copper strip and wrap it with three sheets of toilet paper. Then roll the zinc strip together with the remaining two sheets of toilet paper. Once this is done, take some copper wire and tie it around the power cell in order to prevent the paper from getting torn when wet. Take a pulley, which should fit perfectly on the PVC Coupling, make two holes for the metal strips to go through, insert the strips in the holes and seal with superglue.
To do this, ASCAS provided a full tutorial sometime ago, which in case you have not followed before, you should do so now. Here it is. The only difference is that here we need a more compact circuit, so the transistor should be fitted below the LED’s board, while the toroidal core should go above it.
All you need to do is to solder the wires on the power cell and add glue around the coupling. Place the LED’s reflector onto the coupling and allow to dry.
Here you need the PVC pipe, place a cork or a small piece of acetate to close up the non-threaded side. This will allow you to fill it up with water during the next step.
Now that the pipe is nicely closed on one side, bring it to the tap and fill it up. You can use other liquids too, not only the tap water, which could provide only half an hour of light. Salt water is rich in electrolytes and allows you to use the flashlight for up to 2 hours, but if you pick something like vinegar or gatorade, you might be able to enjoy it for as long as 10 hours.
Images (c) The Instructables, member ASCAS