Elenco Circuit Maker Skill Builder 125 - Manual (Page 20)

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Project #17 Hi-Low Fan
Fuse or Lose
!
WARNING:
Moving parts. Do not
touch the fan or motor
during operation.
!
WARNING:
Moving parts. Do not
touch the fan or motor
during operation.
Project #18
The principle of removing resistance to
increase motor speeds is only one way of
changing the speed of the motor. Commercial
fans do not use this method because it would
produce heat in the resistor and fans are used
to cool circuits by moving air over them.
Commercial fans change the amount of
voltage that is applied to the motor using a
transformer or other electronic device.
Build the circuit shown on the left.
When you close the slide switch (S1), current flows from the batteries
through the slide switch (S1), motor (M1), the lamp (L1), and back to
the battery (B1). When the press switch (S2) is closed, the lamp is
shorted and motor speed increases.
Use the circuit built in Project #17.
When you close the slide switch (S1), current flows from the batteries
through the slide switch (S1), the lamp (L1), motor (M1), and back to the
battery (B1). Pretend the 2-snap wire marked fuse in the drawing on the
left is a device that will open the circuit if too much current is taken from
the battery. When press switch (S2) is closed, the light is shorted and
motor speed increases due to an increase in current to the motor. While
still holding press switch (S2) down, remove the 2-snap wire marked
fuse and notice how everything stops. Until the fuse is replaced, the
open circuit path protects the electronic parts. If fuses did not exist,
many parts could get hot and even start fires. Replace the 2-snap wire
and the circuit should return to normal.
Many electronic products in
your home have a fuse that will
open when too much current is
drawn. Can you name some?
CM-125_Manual_031514.qxp_CM-125_Manual_031514 4/2/14 12:19 PM Page 20