Elenco Electronic Playground 50-in-1 Experiments - Manual (Page 52)

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You need some more parts to do this experiment, so
you’re going to draw them. Take a pencil (No. 2 lead is
best but other types will also work), SHARPEN IT, and fill
in the 4 rectangles you see below. You will get better
results if you place a hard, flat surface between this
page and the rest of this booklet while you are
drawing. Press hard (but don’t rip the paper) and fill in
each several times to be sure you have a thick, even
layer of pencil lead and try to avoid going out of the
boundaries.
Actually, your pencils aren’t made out of lead anymore
(although we still call them “lead pencils”). The “lead” in
your pencils is really a form of carbon, the same material
that resistors are made of. So the drawings you just
made should act just like the resistors in your Electronic
Playground.
Connect the wires according to the Wiring Checklist. It’s
the same basic oscillator circuit you have been using.
Take the two loose wires and touch them to opposite
ends of the smallest rectangle you drew, you should hear
a sound like an alarm. Note: you may get better
electrical contact between the wires and the drawings if
you wet the wires with a few drops of water or saliva.
What kind of sound do you think you’ll get with the other
drawings? (Hint: think about how resistors operate in
series and parallel combinations, or think in terms of the
water pipes). Now touch the loose wires to opposite ends
of the other rectangles you drew (you may need to wet
the wires again) and see if you were right. You can also
slide one of the wires along the drawing and see how the
sound changes.
Making the drawn resistors longer should increase the
resistance (resistors in series or longer water pipes)
while making them wider should reduce the resistance
(resistors in parallel or larger water pipes). So all 4
rectangles should produce the same sound, though you
will see variations due to how thick and evenly you filled
in the rectangles, and exactly where you touch the wires.
If your 4 shapes don’t sound similar then try improving
your drawings.
Be sure to wash your hands after this test, unless you’re
going on to Experiment 35 now.
EXPERIMENT #34: Drawing Resistors
Shapes to be Drawn
Use a SHARP No. 2 pencil, draw
on a hard surface, press hard and
fill in several times for best results.
Wiring Checklist:
o 19-to-25
o 5-to-21
o 6-to-22
o 20-to-26
o 18-to-43
o 23-to-32-to-unconnected
(the unconnected wire
should be long)
o 33-to-42-to-44
o 45-to-unconnected (the
unconnected wire should
be long)
o 27-to-24
Schematic
Loose
Wires