Elenco Upgrade Kit SC500 to SC750 - Manual (Page 84)

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Project #689
OBJECTIVE: To build an out of balance turn off circuit.
Out of Balance
Project #690
OBJECTIVE: To sound an alarm when something is shaken.
Vibration Alarm
Turn on the slide switch (S1) and shake the circuit or bang on the table;
an alarm will sound. Try banging on the table in a regular pattern, and
see if you can make the alarm sound continuously.
The vibration switch (S4) triggers the SCR (Q3) connecting the relay’s
(S3) coil to the battery (B1). The relay’s contacts switch, turning the
motor (M1) off, and lighting the lamp (L2). The lamp will stay lit until
the slide switch (S1) is turned off.
Turn the slide switch on; the motor starts to spin. If the motor generates
enough vibration, the switch will trigger the SCR, turning off the motor
and lighting the lamp. If the motor keeps spinning, tap on the table to
trigger the vibration switch.
!
WARNING: Moving parts. Do not touch the fan or
motor during operation. Do not lean over the motor.