Manual

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37. Reed Switch Motor
Build the circuit, press the switch (62), when you move
the magnet (7) towards the reed switch (83), you will
see the fan blade (60) of the motor (95) start spinning.
When you move the magnet (7) away, the fan blade (60)
will stop spinning. Reed switches can actually be used to
create what are called brushless motors.
38. Reed Switch vs. Mechanical Switch
Build the circuit by replacing the switch (62) with the press
switch (61). Press and hold the press switch (61). When you
move the magnet (7) towards the reed switch (83), you will see
the fan blade (60) of the motor (95) start spinning. When you
move the magnet (7) away, the fan blade (60) will stop spinning.
One of the benets of reed switches over mechanical switches
like the press switch (61) is reliability/lifetime. Mechanical
switches can wear out more quickly as you use them, and some
studies show that reed switches can be used 10,000 times
more often than mechanical switches before they wear out.
39. Ohm’s Law Revisited
Build the circuit, press the switch (62). You will hear the alarm
(78) start wailing while the lamp (76) will light dimly. You may need
to be in a dark room to see the dim light from the lamp (76). There
is more resistance in the alarm (78) than in the lamp (76) which
means the voltage across the lamp (76) is much less than the
voltage across the alarm (78), which is why the lamp (76) is dim.
WARNING: Moving parts. Do not touch
the fan or motor during operation. Do
not lean over the motor.
!