Elenco LIGHT - Manual (Page 28)

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Project 17 High Power Fiber Optics
Project 18
Build the circuit as shown. Place the clear cable holder on the
white LED (D6) 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) and move the lever on the
adjustable resistor (RV) around. The sound from the speaker
(SP) changes as you move the lever on RV.
Try removing the black cable holder and just holding the fiber
optic cable next to the phototransistor with your fingers. Hold it
at different angles and compare the sound. You may not hear
anything, due to background light in the room. Take the circuit
into a dark room or place your fingers around the
phototransistor to block the room light to it. Now put the black
cable holder back on, remove the clear cable holder, and try
holding the fiber optic cable at different positions around the
white LED. You can also replace the white LED with the red LED
(D1) or the color LED (D8).
High Color
Optics Sounds
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 strobe
IC (U23) and speaker (SP).
Black
Clear
The circuits on this page are similar to
projects 12 and 14, but have the fiber
optic transmitting sub-circuit (with the
LED) and the receiving sub-circuit (with
the phototransistor) using the same
voltage sources. Normally the
transmitting and receiving circuits will
be in different locations with separate
voltage sources, but they were
combined here to increase the power.
Black
Clear