Loading ...
Loading ...
Loading ...
50
Microphone Control
OBJECTIVE: To use a microphone to control the brightness of
an LED.
In this circuit, blowing on the microphone (X1) changes the LED (D1)
brightness.
The resistance of the microphone changes when you blow on it. You
can replace the microphone with one of the resistors to see what
resistor value it is closest to.
Project #136
Do not place the fan onto the motor (M1). Turn the slide switch (S1) on. The
motor rotates clockwise, and the green LED (D2) lights. When you connect
the positive (+) side of the battery (B1) to the positive (+) side of the motor,
it spins clockwise. Turn the slide switch off and press the press switch (S2).
Now the fan spins the other way and the red LED (D1) lights. The positive
(+) side of the battery is connected to the negative (–) side of the motor.
The polarity on the motor determines which way it rotates.
Now place the fan on the motor, and turn on S1 or S2 (not both). Now one
of the lamps (L1 or L2) lights as the motor spins, but the LED is dim.
The motor needs a lot of current to spin the fan, but only a little current to
spin without it. In this circuit, a lamp lights when the motor current is high,
and an LED lights when the motor current is low. The lamps also prevent a
short circuit if both switches are on.
LED Fan Rotation
Indicator
OBJECTIVE: To build an LED fan rotation indicator.
Project #135
Loading ...
Loading ...
Loading ...