Elenco Snaptricity® - Manual (Page 45)

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3-Speed Motor (II) Project #35
Educational Corner:
When wires from different parts of
a circuit connect accidentally then
we have a “
short circuit ”. You’ve
probably heard this term in the
movies; it usually means trouble.
A short circuit is a wiring path that
bypasses the circuit resistance,
creating a no-resistance path
across the batteries. This will
damage components and/or
quickly drain your batteries. Be
careful not to make short circuits
when building your circuits.
Always check your wiring before
turning on a circuit. See page 7
for examples of short circuits.
Electric Paths
5V
5V
+
!
WARNING: Moving
parts. Do not touch
the motor during
operation.
Push the press switch (S2) to turn on the motor and use
the slide switches (S5) to control its speed. The meter
measures the voltage across the motor. You may need to
give the motor a push to get it started, but do not touch it
while it is spinning.
Operation
Here you control the motor speed by diverting some of the
current to the lamps (L4). Turning on the other lamps diverts
current away from the motor, reducing the voltage across it and
slowing it down. This circuit is the same as project 34, except it
measures the motor voltage instead of the circuit current.
Description
Build the circuit. Set the meter (M5) to the 5V scale and
leave the fan off the motor (M1).
Assembly
Snappy says: the name “short circuit” refers
to how the current through the circuit
bypasses (jumps around) other components
in the circuit. It is the “easiest” path through
the circuit, it is not always the “shortest”.
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