NATURE & DECOUVERTES 42000880 Manual Del Usuario página 29

2.5V 18
2 2
3V +
19
15
2 2
OF FO N
2.5V 18
2 2
3V +
19
15
2 2
OF FO N
7. Glowing LED (Light Emitting Diode)
A diode is an unidirectional semiconductor. A LED emits light when a current passes
through it. Assemble as illustrated. Turn on the slide switch 15 . The LED
brightly while the 2.5V lamp 18 either remains dark or glows faintly. This is because
the LED requires a smaller amount of current (110mA) than does the lamp (300mA).
8. Unidirectional Conductivity
Assemble as illustrated. Turn on the slide switch . Both the lamp
15 18
remain dark. The LED only conducts electricity in one direction. If the LED is in the
wrong direction, current cannot flow and the circuit is not complete.
56
2.5V 18
A
17 glows
B
2.5V
2
and the LED
17
2
OF FO
9. Conductivity Tester
Assemble as illustrated. This tester identifies conductive and non-conductive materials.
Connect points A and B with the material to be tested. If the item is a conductor(such
as a nail), the lamp 18 lights. If the material is not a conductor (such as wood), the lamp
18 remains dark.
10. Reed Relay Circuit
18
The reed relay is a magnetically controlled switch. Assemble as illustrated. Turn on
13
the slide switch . The LED
15 17
glows faintly. Bring the magnet close to the reed relay
while the LED goes out. Because it is a semiconductor, the LED has greater resistance
17
3V +
than the closed reed relay. The current takes the easier route, bypassing the LED.
11. Alternative Reed Relay Circuit
Replace the 2.5V lamp with the DC motor
18
magnet close to the reed relay
goes out.
19
WARNING: moving parts. Do not touch the fan or motor during operation.
15
N
57
glows brightly while the lamp either remains dark or
18
. The lamp glows brightly
13 18
. Turn on the slide switch . Bring the
24 15
. The DC motor accelerates while the LED
13 24 17
+
24