Datasheet-1

Project 34
3-Speed Motor
Build the circuit, set the switcher (S6) to the middle position (off), set the
meter (M5) to the 1A setting, and leave the fan off the motor (M1). Push
switch (S2); the motor spins, and the meter measures the current. Turn
on the slide switch (S1) or set the switcher to the left position to adjust
the motor speed. You may need to give the motor a push to get it started,
but do not touch it while it is spinning. Sometimes the lamps may not
light.
Here you control the motor
speed by diverting some of
the current to the lamps.
When S1 and S6 are off the top lamp
should be dim or off, why?
1A
!
WARNING: Moving parts. Do not
touch the fan during operation.
!
WARNING:
Do not lean
over the motor.
Now place the fan on the motor. Turn on the slide switch and set the
switcher to the left (so both switches are on), and push the press switch.
The motor will not spin.
Now turn off the slide switch and set the switcher to the middle position
(so both switches are off), push S2 to get the motor spinning, then set
the slide switches back (so both are on) while still pushing S2.
Note: Motor performance may vary, in rare cases it may spin in all switch
settings.
The motor could not start spinning with the other lamps on, but it
will keep spinning as long as you keep pushing S2. Why?
The surfaces touched by the motor
shaft offer some resistance to motion,
called friction. Once the initial friction
is overcome, it doesn’t take much ef-
fort to keep the motor spinning. This
is especially important when the
motor is trying to start the fan, due to
the fan weight.
+
-39-
SC_STEM1_manual_PRINT.qxp_Layout 1 7/13/17 4:43 PM Page 40