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Project #11
The Diode Dude
Project #12
One Way Works
An electronic component that
needs to be connected in one
direction is said to have polarity.
Other parts like this will be
discussed in future projects.
Placing the LED in backwards does
not harm it because the voltage is
not large enough to break down this
electronic component.
LEDs are used in all types of electronic
equipment to indicate conditions and
pass information to the user of that
equipment. Can you think of something
you use everyday that has an LED in it?
Build the circuit shown on the left.
When you turn on the slide switch (S1), current flows from the batteries
(B1) through the switch, through the 100
W
resistor (R1), through the
LED (D1, light emitting diode) and back to the battery. The turned on
switch completes the circuit. The resistor limits the current and prevents
damage to the LED. NEVER PLACE AN LED DIRECTLY ACROSS
THE BATTERY! If no resistor is in the circuit, the battery may push
enough current through the LED to damage the semiconductor that is
used to produce the light.
+
+
Rebuild the circuit used in Project #11 but put the LED in as shown on
the left.
This time when you turn on the slide switch (S1), current does not flow
from the batteries (B1) through the 100
W
resistor (R1) or through the
LED (D1), and hence the LED does not light up. This is because the
LED is in backwards. The LED is like a check valve that lets current
flow in only one direction (into the + end and out the other end).
CM-125_Manual_031514.qxp_CM-125_Manual_031514 4/2/14 12:19 PM Page 17
