Elenco Electronics 202 - Manual (Page 17)

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Project #4
OBJECTIVE: To show how resistance can change the sound
from the speaker.
Build the circuit shown on the left, but leave the fan off the motor (M1).
When you turn on the slide switch (S1), the music may play for a short
time and then stop. After the music has stopped, spin the motor with
your fingers. The music should play again for a short time, then stop.
Now replace the 100 Ω resistor (R1) with a 3-snap wire, and notice how
the sound is affected.
In this project, you changed the amount of current that goes through
the speaker (SP) and increased the sound output of the speaker.
Resistors are used throughout electronics to limit the amount of
current that flows.
Adjusting Sound Level
Project #3
OBJECTIVE: To show how a motor works.
Hear the Motor
Place the fan on the motor (M1). Press the press switch (S2) and
listen to the motor. Why does the motor make sound?
A motor uses magnetism to convert electrical energy into mechanical
spinning motion. As the motor shaft spins around it connects/
disconnects several sets of electrical contacts to give the best
magnetic properties. As these contacts are switched, an electrical
disturbance is created, which the speaker (SP) converts into sound.
If you replace the motor with the 6V lamp (L2), then it will work the
same, but only make noise when the lamp is turned ON or OFF.