Elenco Green Projects - Manual (Page 55)

Crank Support
Project #83 Solar Lights Row
Having both LEDs in
series resists the flow
of electric current
more than just one,
making it easier for the
solar cell to run them.
5V
Think of the yellow LED
as an emergency light in
your home. When the
main power goes out, it
can run for a while on
battery backup or a hand
crank generator.
Assemble the pivot, mount the solar cell (B7) on it, and
place it in the circuit as shown. Connect the solar cell to
the circuit using the red and black jumper wires. Place
the circuit so the solar cell is in bright sunlight or close
to an incandescent light bulb. Set the meter (M6) to the
5V setting.
The meter is measuring the voltage produced by the
solar cell. Adjust the position of the solar cell to make
the highest voltage you can. Now push the press switch
to run the red and white LEDs (D1, D5) with the solar
cell. Notice how the voltage produced drops a little when
the LEDs are connected, but not as much as when only
the yellow LED was in the circuit (the Solar Power
project).
Note: The voltage produced is actually twice that shown
on the meter (so a 3V reading is really 6V), because a
resistor in the pivot stand is changing the scale.
0.5mA
Build the circuit by setting up the parts as shown. Be
sure to place the parts with their (+) side oriented as
shown. Set the meter (M6) to the 0.5mA or 50mA
setting. Set the slide switch (S5) to position B to connect
the rechargeable battery (B4) to the yellow LED (D5). If
the battery is charged, the LED will light and the meter
will show that an electric current is flowing out of the
battery. The 0.5mA meter scale will show a high current
while the 50mA scale may show little or no current.
Turn the handle on the hand crank (HC) counter-
clockwise (opposite to the direction a clock turns) to
have it take over powering the yellow LED. When you
crank fast enough, the red LED (D1) will turn on and
the meter will no longer show any current flowing.
Warning: the hand crank is sturdy but not
indestructible. If you push hard on it or crank it really
fast you may break it.
Project #84
50mA
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