Project 118
Pencil Alarm
Project 119
Pencil Sound
Remove the jumper connected
to point Y (as shown in the
drawing) and connect it to point
X instead. Touch the loose ends
to the pencil drawing again, the
sound is different now.
Project 120
Pencil Alarm
Variant
Next connect a 2-snap wire
between points X & Y connect
the jumper to either point.
Touch the loose ends to the
pencil drawing again, you
hear a different sound.
Project 121
Another Pencil
Alarm Variant
Now remove the 2-snap wire
between X & Y and connect it
between X & Z, connect the
jumpers to W & Y. Touch the loose
ends to the pencil drawing again,
you hear yet another sound.
Now you can draw your own
shapes and see what kinds of
sounds you can make.
Build the circuit shown and connect the two jumpers to it, leave the loose
ends of the jumpers unconnected for now. There is one more part you
need and you are going to draw it. Take a pencil (No. 2 lead is best but
other types will also work).
SHARPEN IT
, and fill in the shape below. You
will get better results if you place a
hard
, flat surface directly beneath this
page while you are drawing. Press
hard
(but don’t rip the paper), and fill
in the shape
several times
to be sure you have a
thick, even layer
of
pencil lead.
Turn on the slide switch (S1) and take the loose ends of the jumpers,
press them to the shape and move them around over the drawing. If you
don’t hear any sound then move the ends closer together and move over
the drawing, add another layer of pencil lead, or put a drop of water on
the jumper ends to get better contact.
Now you can draw your own shapes and see what kinds of sounds you
can make.
W
x
Y
-48-
The black core of
pencils is graphite,
the same material
used in resistors.
Z
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