Elenco Circuit Maker Skill Builder 125 - Manual (Page 33)

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Project #55 Reflection Detector
Project #56 Music Reflection
Detector
How good of a reflector is a black piece of
paper? Tin foil? How about your hand?
Build the circuit to the left. Place it where there won’t be any room light
hitting the photoresistor (RP) (such as in a dark room or under a table),
and then turn it on. The 2.5V lamp (L1) will be bright, but there should
be no sound.
Take a small mirror and hold it over the lamp and photoresistor. You
should hear sound now. You have a reflection detector! You can also
use a white piece of paper instead of a mirror, since white surfaces
reflect light.
Build the circuit to the left. Place it where there won’t be any room light
hitting the photoresistor (RP) (such as in a dark room or under a table),
and then turn it on. The 2.5V lamp (L1) will be bright, and one song
may play, but then there should be no sound.
Take a small mirror and hold it over the lamp and photoresistor. You
should hear sound now. You have a music reflection detector! You can
also use a white piece of paper instead of a mirror, since white
surfaces reflect light.
CM-125_Manual_031514.qxp_CM-125_Manual_031514 4/2/14 12:19 PM Page 33