Manual

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23. Reversing a DC Motor
Build the circuit to the left. Press and hold the press switch
(61) and the motor (95) will spin clockwise. Release the
press switch (61) and the motor (95) will stop. Now put
the motor (95) in backwards reversing its direction (95
should be upside down now) and swapping it with the 4-wire
in grid locations D2 through G2. Press and hold the press
switch (61) and the motor (95) now spins counterclockwise.
Notice that the direction the motor (95) spins is related to
the direction the current ows through the motor (95). This
is because the force created on the motor shaft is related
to the direction that the current ows through the magnetic
eld in the motor (95). You can look up Fleming’s left hand
rule for more details on how the relationship between the
current ow, magnetic eld and force that creates motion.
24. Morse Code Using Fiber
Build the circuit above, press the switch (62), then hold the press switch (61). The
colorful LED (72) will turn on and the ber optic tree (40) will light up with the colors
of the colorful LED (72). Release the press switch (61); the colorful LED (72) will turn
off. The International Morse Code is shown to the left where a dot represents a quick
push of the press switch (61) and a dash represents holding the press switch (61) for a
second. Try sending letters or a code to a friend and see if they can decode it by looking at
how the ends of the bers ash on and off.
WARNING: Moving parts. Do not
touch the motor during operation. Do
not lean over the motor.
!
Morse Code