Elenco Snaptricity&reg - Manual (Page 64)

Project #54
Educational Corner:
How does the fan rise? Think first about how you swim. When
your arms or legs push water behind you, your body moves
ahead. A similar effect occurs in a helicopter - the spinning
blades push air down, and create an upward force on the
blades. If the blades are spinning fast enough, the upward
force will be strong enough to lift the helicopter off the ground.
While the switch is pressed, the motor rotation locks the fan
on the motor shaft. The fan does not spin fast enough to lift
the entire circuit off the ground. When the motor is turned
off, the fan unlocks from the shaft. The fan rises into the air
like a helicopter, since it is no longer held down by the weight
of the full circuit.
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Electric Paths
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When the motor is blowing air up, it is a fan - just like
the ones in your home. It will cool you off on a hot day.
When the motor is sucking air in, it is a propeller - just
like the ones on helicopters or small airplanes.
Description
Set the slide switches (S5) to position B and push the
press switch (S2). The fan blades suck in air around
the motor (M1) and push it straight up. Hold a sheet
of paper above the motor, it will get pushed up and
away from the fan.
Flip the slide switches to position C and push the
press switch again. The fan spins the other direction
and sucks in air from above and pushes it down to the
table. If the fan is spinning fast enough, then it will
rise into the air when you release the press switch. If
you hold a sheet of paper near the motor, it will get
sucked into the fan.
Operation
Build the circuit shown.
Assembly
Propeller and Fan
!
WARNING: Moving parts.
Do not touch the fan or
motor during operation. !
WARNING:
Do not lean
over the motor.
Snappy says: switching circuits like this are
commonly used to control motors in products like
remote-controlled cars. Electronic controlled
transistors are used in place of the switches, and
the motor drives the wheels in the car.
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