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Bike Dynamo As Cellphone Charger
Emmanuel and Gideon's Page
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Joule Thief Cell-Phone Charger
A "Joule Thief" is a simple circuit which 'boosts' a low DC voltage to a higher voltage in pulses. There's a lot of interesting articles on the web: just google "Joule Thief" for much more information on what it is and how it works. This project is specifically to design, build, and teach a JT
application as an LED driver
) that is suited for a variety of inputs and gives a safe charging output.
as for the
Very useful for turning low-voltage solar cells (which the lab has in abundance) into cell-phone chargers
The alternative is cutting the cells into pieces and attaching them in series, a messy process
an early circuit charged the battery excessively slowly, but the newer version should be higher current
why are you working on it?
Because a simple solar cell-phone charger would be exceptionally useful, and this would allow a wider range of panels.
theoretical cost breakdown (1 cedi = 100 pesawa = around 0.56 euros/0.71 US dollars)
(all prices more than expected)
Panel - around 1 Watt - 1 cedi
Circuit - 50 pesewas to 1 cedi
Enclosure - a few cedi for wood, clear acrylic, screws
Total: 5 cedi to make something that would take only 2-3 hours of sun to fully charge a phone
Joule Thief Light
for the circuit: the only difference is that the lights are replaced by a reversed 4.7V zener diode (if charging a battery directly) or by a 5V regulator (through cell-phone: untested, maybe unncessary).
Solar Powered Reading Light
: the circuit (at right) will charge a cell-phone battery to 100% if the red LED is replaced with a 20mA blue or white one (and if R2 replaced with a 10-20 ohm resistor it'll light LED2 safely).
As the lab has about a dozen 100 uH inductors, this is definitely worth a shot.
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