Elenco Snap Circuits SOUND &reg - Manual (Page 74)

Turn on both slide switches (S1). Move the lever on
the adjustable resistor (RV) all the way to the left or
right, and watch the brightness of the color LED (D8).
The light should be a little brighter when RV’s lever is
to the left.
Now move RV’s lever toward one side, but not all the
way. There should be a larger difference between the
same positions on the left compared to the right.
Project 158
Continuity
Tester
Use the preceding circuit,
but instead connect the
loose ends of the jumper
wires to different
materials in your home. If
you hear sound, then the
material you tested has
low resistance and is a
good conductor of
electricity.
Project 159 High Low Light
The left side of RV is connected to 6V, while
the right side is only connected to 3V; so the
color LED will be brighter when RV’s lever
is to the left. Moving the lever toward the
middle increases the resistance in the
circuit, and the higher voltage left side will
be less affected than the right side.
Project 157 Water Alarm
Build the circuit, and initially leave the loose
ends of the red & black jumper wires
unconnected. Turn on the slide switch (S1);
nothing happens. Now place the loose ends
of the red & black jumper wires into a cup of
water, without their snaps touching each
other. You should hear a tone now, indicating
that you have detected water!
Don’t drink any water used here.
You could place this circuit
in your basement, then it will
sound an alarm if your
basement starts to flood
during a storm.
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