Elenco Upgrade Kit SC500 to SC750 - Manual (Page 53)

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Project #617
OBJECTIVE: To construct a circuit that indicates vibration.
Vibration Sounder
Project #618
OBJECTIVE: To use the SCR to start a circuit.
SCR Noise Circuit
Turn on the slide switch (S1) and nothing happens. The SCR (Q3)
connects the circuit to the batteries and, until the SCR’s gate goes
high, the circuit is off. Press the press switch (S2) and the motor (M1)
spins and the LED (D2) and bulb (L2) light. Increase the sound from
the speaker (SP) by pressing the press switch.
As the motor (M1) spins, it generates an AC voltage amplified by U4.
The output from U4 lights the LED (D2) and makes noise from the
speaker (SP). With the fan not installed, turn on the slide switch (S1)
and you hear the high tone of the spinning motor. Now, install the fan
and hear the difference.
!
WARNING: Moving parts. Do not touch the fan or
motor during operation. Do not lean over the motor.
!
WARNING: Moving parts. Do not touch the fan or
motor during operation. Do not lean over the motor.