Elenco Electronics 202 - Manual (Page 21)

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Project #11
OBJECTIVE: To make a circuit that launches the fan blade to
simulate a flying saucer.
Rebuild the circuit from project #2, but reverse the polarity on the motor
(M1) so the negative (–) on the motor goes to the positive (+) on the battery.
When you turn on the slide switch (S1), the motor will slowly increase
in speed. When the motor has reached maximum rotation, turn the
slide switch off. The fan blade should rise and float through the air like
a flying saucer. Be careful not to look directly down on fan blade when
it is spinning.
The air is being blown down through the blade and the motor rotation
locks the fan on the shaft. When the motor is turned off, the blade
unlocks from the shaft and is free to act as a propeller and fly through
the air. If the speed of rotation is too slow, the fan will remain on the
motor shaft because it does not have enough lift to propel it. The motor
will spin faster when both batteries are new.
If the fan doesn’t fly off, then turn the switch on and off several times
rapidly when it is at full speed.
Flying Saucer
Project #12
OBJECTIVE: To show how voltage affects speed of a DC motor
and can decrease the lift of the saucer.
Change the circuit in project #11 by adding the lamp (L2) in series with
the motor (M1) as shown in the diagram on the left.
When you place the lamp in series with any electronic device, it will
draw less current because it adds resistance. In this case, the lamp in
series reduces the current through the motor, and that reduces the top
speed of the motor. Turn on the slide switch (S1) and wait until the fan
reaches maximum speed. Turn the switch off and observe the
difference in the height due to the lamp. In most cases, it may not even
launch.
Decreasing Saucer Lift
!
WARNING: Moving parts. Do not touch the fan or
motor during operation.
! WARNING: Do not lean over the motor.
!
WARNING: Moving parts. Do not
touch the fan or motor during operation.
!
WARNING: Do not
lean over the motor.