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Project #489
Instead of driving a speaker (SP) with the music IC (U1), you can see
it by using the meter (M2). Turn on the switch (S1) and the meter
deflects according to the rhythm of music. When music stops, press
switch (S2) once to start the music again.
Hand-Control Meter
OBJECTIVE: To understand music deflection.
OBJECTIVE: To control the circuit using
light.
Use the circuit in project 489. Replace the
switch (S2) with the photo resistor (RP). The
music IC (U1) outputs a signal, as long a light
is present on the photo resistor. The photo
resistor is like a short, connecting the pin to
the battery. Cover the photo resistor with your
hand, the resistance goes up, and the music
stops.
Light-Control
Meter
Project #490
OBJECTIVE: To start the circuit using an
electric motor.
Electric-
Control Meter
Project #491
OBJECTIVE: To start the circuit by using a
speaker.
Sound-Control
Meter
Project #492
Use the circuit in project 489. Place the motor
(M1) across points A & B. Turn on the switch
(S1) and the meter (M2) deflects and swings
according to the rhythm of music. When
deflection stops, rotate motor to start the
music again. The voltage generated by the
motor triggers the IC again.
Use the circuit in project 489. Place the
whistle chip (WC) across points A & B. Turn
on the switch (S1) and the meter (M2) deflects
and swings according to the rhythm of music.
When deflection stops, clap your hands next
to the speaker (SP), the music plays again.
The clapping sound vibrates the plates in the
whistle chip, creating the voltage needed to
trigger the IC.
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