Data Sheet

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37. Hand Crank Generator-controlled
Parallel Siren & Bi-directional LED
Build the circuit, turn the hand crank generator (94
& 99) clockwise and blue light will emit from the
bi-directional LED (71) and the alarm (78) will sound
too. Turn the hand crank generator (94 & 99) counter-
clockwise and the alarm (78) will turn off while red light
emits from the bi-directional LED (71).
Generators usually output direct current (DC) power
like in this circuit, but some generators have internal
power inverters that convert this to alternating current
(AC) power. DC power provides a steady voltage,
like your “AA” batteries that each provide about
1.5V. AC power provides a voltage that changes like
a sine wave and alternates the polarity of
the voltage.
38. Hand Crank Generator for Cellphones
Build the circuit, turn the hand crank generator (94 &
99) and all three LEDs will be turned on. One practical
use for hand crank generators today is to charge your
cellphone when low on battery power (you can purchase
such devices online or in some stores today).
1st level
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