| The light from this thing is weak.
It took about a minute of vigorous shaking to get the first bit of light from it.
After a few more minutes of shaking, the capacitor was fully charged. It might
be okay for finding your keys in the dark but not much more. |
|
The complete schematic for this device
is shown below. A few things should be pointed out. First, they use some
very cheap 1N4001 diodes in the bridge rectifier circuit instead more efficient
Schottky diodes. They also use a small 0.5 Farad cap with a 5.5 volt rating.
I noticed that that this kind of super capacitor was originally designed for
maintaining data in memory chips and has a rather high internal equivalent series
resistance. This reduces the overall efficiency, since the device can’t be
charged or discharge very quickly. Some of the power that should go to the LED
will end up being dissipated inside the capacitor. Better super capacitors do exist. |
