Elenco Green Projects - Manual (Page 73)

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Project #120 Parallel Cranking
Hand Charger
Use the hand crank (HC) to charge the
battery (B4), the meter (M6) or yellow LED
(D5) show how fast you are charging it.
Turn the hand crank (HC) slowly
clockwise, just enough to turn on the red
LED (D1). Then crank just a little faster,
until the yellow LED (D5) also comes on.
Then crank fast to see how bright each
LED will get (but don’t crank excessively
fast).
If you turn the crank counter-clockwise the
LEDs will not light, but the horn (W1)
sounds.
Project #119
50mA
The yellow LED needs a little more voltage to turn on, but can get much
brighter. LEDs are manufactured with two regions of permanent
electrical charge. Once the voltage exceeds a turn-on level, the
resistance becomes very low in one direction, and some energy is
emitted as light.
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