Project 5
Musical Doorbell
Turn on the slide switch
(S1). A tune may play for a
sort time and then stop.
When there is no sound,
push the press switch (S2)
to play a tune. The press
switch acts like a musical
doorbell.
Project 7
Space War
Alarm Combo
Build the circuit
shown. Turn on the
slide switch (S1),
press the press
switch (S2) several
times, and cover
and uncover the
phototransistor (Q4)
to hear all the sound
combinations.
The lower-right snap of the music IC is like
an electrical gate, opening and closing
quickly to let small bursts of electric current
flow in. The bursts of electric current also
flow through the speaker (which produces
sound). The music IC produces the tune by
adjusting the pattern of current bursts
through the speaker.
Musical integrated circuits are used
to entertain young children in many
of the toys and chairs made to hold
infants. If the music is replaced with
words, the child can also learn while
they are entertained. Because of
great advances in miniaturization,
many songs are stored in a circuit
no bigger than a pinhead.
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Project 6
Music Circuit
Build the circuit
shown on the left.
Turn on the switch
(S1). A tune plays
for a short time and
then stops. Push
the press switch
(S2) and music
plays until you
release S2. Spin
the motor (M1) top
with your fingers to
play a short tune.
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