Elenco Projects 1-101 - Manual (Page 13)

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Project #9
OBJECTIVE: To make a circuit that detects the conduction of
electricity in different materials.
Rebuild the circuit from Project #7 but leave the slide switch (S1) out
as shown on the left.
When you place a metal paper clip across the terminals as shown in
the picture on the left, current flows from the batteries (B1) through the
resistor (R1), through the LED (D1), and back to the battery. The
paper clip completes the circuit and current flows through the LED.
Place your fingers across the terminals and the LED does not light.
Your body has too high of a resistance to allow enough current to flow
to light the LED. If the voltage, which is electrical pressure, was higher,
current could be pushed through your fingers and the LED would light.
This detector can be used to see if a material like plastic is a good
conductor or a poor conductor.
Conduction Detector
Project #10
OBJECTIVE: To combine the sounds from the space war and
alarm integrated circuits.
Build the circuit shown and add the jumpers to complete it. Turn it on,
press the press switch (S2) several times, and wave your hand over
the photoresistor (RP) to hear all the sound combinations. If the sound
is too loud you may replace the speaker (SP) with the whistle chip
(WC).
Space War Alarm Combo
To learn more about how circuits work, visit www.snapcircuits.net or page 45 to find out about our Student Guides.