Elenco Green Projects - Manual (Page 56)

Crank Sound
Project #85 Crank Charging
Turning the crank
recharges the battery,
so the LED will stay on
much longer!
The electricity produced by the
chemical reaction in the
battery is more stable than that
produced by the generator in
the hand crank. The capacitor
filters the electricity so the
hand crank makes the sound
as good as the battery.
In the preceding circuit, when the hand
crank is powering the yellow LED it is also
charging the rechargeable battery. Change
the circuit to be the one shown here so you
can measure the charging current. Note
that two single snaps are placed beneath
the meter.
The circuit works the same way, except that
now the meter shows when electric current
generated by the hand crank is flowing into
the battery. You can use either the 0.5mA
or 50mA meter setting.
If you set the slide switch to position C, the
battery is disconnected and only the hand
crank will run the LED.
0.5mA
50mA
Project #86
50mA
Modify the preceding circuit to be the one shown
here. Set the meter (M6) to the 50mA setting. Set
the slide switch (S5) to position B to connect the
rechargeable battery (B4) to the horn (W1). The
meter (M6) measures the current.
Now set the switch to position C to disconnect
the battery, and turn the handle on the hand
crank counter-clockwise to power the horn.
Notice that the horn sound is not as clear as
when the battery powered it.
Add the 470 μF capacitor (C5) across point A,
base grid locations C3 to E3 (“+” on top). Now
the sound with the hand crank is clearer and
louder.
+
A
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