Data Sheet

28. Magnet 2-speed Fan

Build the circuit to the left. Press the switch

(62), the lamp (76) will turn on dimly and the

fan will spin slowly. Did you notice that the lamp

(76) started out being bright and then got dim?

This is because motors have very high startup

currents, but once they gain speed the current

through the motor drops. You can increase the

speed of the motor (95) and fan in this circuit by

moving the magnet towards the reed switch (83).

29. Speed-controlled Fan

Replace the reed switch (83) with the press

switch (61). By pressing the press switch

(61) you can control the speed of the fan. This

demonstrates how the fan speed in the ceiling

fan in your house is changed when you pull the

chain on the ceiling fan.

30. Testing Conductors

Build the circuit to the left. This tester can check whether a material is

conductive or not. You just need to connect the material across the touch

plate’s (80) shiny area. If the LED (69) turns on it means the material is a

conductor. If the LED (69) does not turn on, it means the material is an

insulator. The brightness of the LED (69) also tells how good a conductor

the material is, where better conductors make the LED (69) brighter and

poorer conductors make the LED (69) dimmer. You may be able to see

the brightness level of the LED (69) better in a dark room.

-29-

WARNING: Moving parts. Do not touch

the fan or motor during operation. Do

not lean over the motor.

1st level