Data Sheet

-46-

61. Light Dimmer

Build the circuit shown on the left, turn on the switch (62) and you will

see the lamp (76) ON and the motor (95) spin at the same time. Now

press the press switch (61) and the lamp (76) gets brighter while the

motor turns OFF.

Pressing the press switch (61) removes the internal resistance of the

motor (95) from the circuit so that more current ows through the lamp

(76) making it brighter. This concept is used in light dimmer circuits.

62. Fused Motor

Replace the press switch (61) with the reed switch (83). Now you can

control the brightness of the lamp (76) by using the magnet (7). Also,

the motor (95) goes off when you place the magnet (7) near the reed

switch (83).

Motors are designed with fuses to limit the current that can be seen by

the motor to prevent res. When you move the magnet (7) near the reed

switch (83), you are simulating a motor fuse popping to protect a motor

from too much current.

63. Voltage and Current in Series Circuits

Build the circuit shown on the left, turn on the switch (62) and you will

see the two LEDs light at the same time. Turn off the switch (62) and

the LEDs will go off.

If you think about Kirchhoff’s laws in projects #42 & #43, you can

conclude that the current through components in series is the same,

while the voltage across components in series are usually different.

WARNING: Moving parts. Do not

touch the motor during operation. Do

not lean over the motor.

1st level