Data Sheet

-28-
19. Resistors
Build the circuit shown on the left, then turn on the switch (62) and you
will see the heart LED (69) and the lamp (76) will be on at the same
time. The heart LED (69) is a little dimmer than it was in project #11
due to the presence of the 100 Ohm (W) resistor (41) that is connected
in series with the heart LED (69). Resistors get their name because they
are designed to resist the ow of current. The 100W resistor (41) in this
circuit limits the ow of current through the heart LED (69) which is why
it is dimmer than in project #11.
20. Power ‘ON’ Indicator
Build the circuit shown on the right, press the switch (62) and the fan
blade (60) of the motor (95) will start running while the star LED (70) is
on. Without the fan blade (60) it is difcult to see if the motor (95) is ‘ON’
when far from the circuit. With the LED (70) in parallel with the motor
(95), a visual indicator that the motor (95) is ‘ON’ can be seen from a
distance. Red LEDs are often used on electrical devices to show they are
‘ON’. Wasted “Watts” cost money and is bad for the environment.
21. Ohms of Resistance
Build the circuit shown on the left, then turn on the switch (62) and you
will see the heart LED (69) and the star LED (70) will be on at the same
time. But the heart LED (69) is much dimmer than the star (LED). This
is because the heart LED (69) has the 1kW resistor (42) in series with
it, while the star LED (70) has only the 100W resistor (41) in series with
it. Larger resistors (higher Ohms (W)) means more resistance, allowing
less current to ow, while smaller resistors (lower Ohms (W)) means less
resistance allowing more current to ow.
WARNING: Moving parts. Do not touch
the fan or motor during operation. Do
not lean over the motor.
!