Elenco Upgrade Kit SC500 to SC750 - Manual (Page 20)

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Project #535
Project #536
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 converts into sound.
This circuit was suggested by Andrew M.
of Cochrane, Alberta, Canada
Turn on the slide switch (S1), you hear a strange sound from the
speaker (SP). Push the press switch (S2) and the sound changes to
a high-pitch siren.
The alarm IC (U2) produces a smooth siren sound, but the
electromagnet (M3) distorts the siren into the strange sound you hear.
Adding the 0.1
μ F capacitor (C2) counters the electromagnet effects
and restores the siren.
OBJECTIVE: To see how the electromagnet can change the
sound from the alarm IC.
Machine Siren
!
WARNING: Moving parts. Do not touch the fan or
motor during operation. Do not lean over the motor.