Elenco LED Fun - Manual (Page 3)

Turn on the switch (S1). The red & blue LEDs (D1 & D9) will be
on. Try replacing either or both of them with the white and color
LEDs (D6 & D8); try all combinations. If the color LED is used
then both will be blinking. For best effects, take the circuit into a
dimly lit room. Place the fiber optic tree on one LED if desired.
Project 8 Double Light Project 10 Series of Lights
Turn on the switch (S1). The LEDs (D1, D8, & D9) will be
dim, and some may not light at all. Try viewing them in a
dimly lit room. You can replace the blue LED with the white
LED (D6), but if you replace the others then none may light.
Use the project 8 circuit but replace the 100W
resistor (R1) with the adjustable resistor
(RV2), connected as shown. Move the lever
on RV2 around and compare the circuit to
project 8, with all combinations of LEDs.
Project 9
Adjustable Double Light
+
+
Project 11 Brightness Comparator
In building the circuit, note that
one of the 4-snap wires is
partially beneath the adjustable
resistor (RV2) and one of the
battery holders (B1). Turn on the
switch (S1) and move the lever
on the adjustable resistor around.
Compare the brightness of the
LEDs (D1 & D6), then replace
either or both of them with the
blue and color LED (D8 & D9).
Try all LED combinations. For
best effects, place the circuit in a
dimly lit room.
This circuit has the LEDs connected in a
series (not in parallel, as in project 5). This
arrangement makes the LEDs dimmer, but
makes the batteries last longer.
By using different materials and
manufacturing processes, LEDs can be made
for different brightness and for wide/narrow
angles of view. The red LED is not as bright
as the others, and can be viewed from a wider
angle; LEDs like this might be used as
indicators. The white LED is very bright
especially when looking dirrectly at it; LEDs
like this might be used in flashlights.
LEDs are like special
one-way light bulbs.
They have a “turn-on
threshold” of voltage
(about 1.5V for red,
2.0V for green, and
3.0V for blue or white)
that must be exceeded
before light is produced,
brightness then de-
pends on the circuit
resistance. This circuit
has 3 LEDs in series, so
the battery voltage must
exceed all of their turn-
on thresholds before
any light is produced.
What is Resistance? Take
your hands and rub them
together very fast. Your
hands should feel warm.
The friction between your
hands converts your effort
into heat. Resistance is the
electrical friction between an
electric current and the
material it is flowing through.
The white LED is
the brightest LED,
due to its material
and manufacturing
process.
SCP-11_021914.qxp_SCP-11_Instructions 3/7/14 10:40 AM Page 3