Elenco LIGHT - Manual (Page 60)

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Project 126 Fiber Fun
Project 127
Fiber Fun
Backwards
Use the preceding circuit but
swap the locations of the
phototransistor (Q4) and the
100k
Ω resistor (R5), keep the
“+” side of Q4 in the same
direction. Now the red LED
will be on whenever the color
LED is off.
Build the circuit as shown.
Place the clear cable holder on
the color LED (D8) and the
black cable holder on the
phototransistor (Q4), then
place the fiber optic cable into
the holders as far as it will go.
Turn on the slide switch (S1).
Light is transmitted from the
color LED, through the fiber
optic cable, to control the NPN
transistor (Q2) and red LED
(D1).
You can replace the red LED
with the white LED (D6), but
the white LED may be dim or
not light.
Project 128 More Fiber Fun
Project 129
Other
Fiber Fun
Use the preceding circuit but
swap the locations of the
phototransistor (Q4) and the
100k
Ω
resistor (R5), keep the
“+” side of Q4 in the same
direction. Now the red LED
will be on whenever the color
LED is on.
Build the circuit as shown. Place the
clear cable holder on the color LED
(D8) and the black cable holder on the
phototransistor (Q4), then place the
fiber optic cable into the holders as far
as it will go. For best performance the
fiber optic cable should stand straight
up in the holders, without bending them.
Turn on the slide switch (S1). Light is
transmitted from the color LED,
through the fiber optic cable, to control
the PNP transistor (Q1) and red LED
(D1). The speaker is used to help limit
the current through the color LED, and
will not make noise.
For more fun, swap the locations of
the color LED (D8) and red LED (D1).
You may also replace either LED with
the white LED (D6), but the white LED
may be dim or not light.
Black
Clear
Clear
Black