Elenco LIGHT - Manual (Page 44)

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Project 64
Low Power Brightness Control
Project 65
Low Power
Resistors & LEDs
Use the circuit from project 64, but replace the
color LED (D8) with the red LED (D1) or white
LED (D6). Vary the adjustable resistor lever to
see how the light varies with each LED. The white
LED may not be on at all.
Project 66 Persistence of Vision
Build the circuit as shown. Place the black fiber optic cable
holder on the white LED (D6) and insert the fiber cable into
the black holder as far as it will go. Turn on the slide switch
(S1). Take the circuit into a dark room and wave the cable
around while watching the loose end. Try it with the lever
on the adjustable resistor (RV) at different settings. The
light coming out the loose end of the fiber optic cable will
separate into short segments or dashes of light.
Build the circuit and turn on the slide switch (S1).
Move the lever on the adjustable resistor (RV) to
vary the brightness of the light from the color
LED (D8). For best effects, do this in a dimly lit
room. At some RV settings the LED will be very
dim, and some of its colors may be totally off.
Black
“Persistence of Vision” works because the light
is changing faster than your eyes can adjust.
Your eyes continue seeing what they have just
seen.
In a movie theater, film frames are flashed on
the screen at a fast rate (usually 24 per
second). A timing mechanism makes a light
bulb flash just as the center of the frame is
passing in front of it. Your eyes see this fast
series of flashes as a continuous movie.