Elenco Snap Circuits SOUND &reg - Manual (Page 43)

Project 53 Brightness Adjuster
Project 54 Brightness
Limiters
Resistors are used to control or limit the flow of electricity in a circuit.
Higher resistor values reduce the flow of electricity in a circuit.
In this circuit, the adjustable resistor is used to adjust the LED brightness,
to limit the current so the batteries last longer, and to protect the LED
from being damaged by the batteries.
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 adjustable resistor can be set for as low as 200 W , or as high as
50,000 W (50k W ).
Project 55
Vary the brightness of the color
LED (D8) using the 500k
W
adjustable resistor (RV3).
Use the preceding circuit, but
replace the 3-snap with one of the
yellow resistors in this set (R1 or
R3). Observe how each changes
the LED brightness at different
settings for the adjustable resistor.
Build the circuit and turn on the slide switch (S1). Move the lever on the
adjustable resistor (RV) to vary the brightness of the light from the color
LED (D8). If desired, you may place the egg LED attachment on the
LED.
Big Brightness
Adjuster
The 500k W adjustable resistor
(RV3) can be set for as low as
200
W , or as high as 500,000 W
(500k W ), so the color LED will
only light on a small portion of
RV3’s range.
The R1 resistor (100 W ) will have
little effect, because the adjustable
resistor (RV) will always dominate
it. Resistor R3 (5.1k
W ) will
dominate when RV is set for low
values, but have little effect when
RV is set at high values.
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