Elenco LIGHT - Manual (Page 77)

Project 169
Delayed Photo Speed Control
Project 170
Delayed
Speed
Control
Use the preceding circuit,
but replace the 100
µ
F
capacitor (C4) with the
much smaller 0.1
µ
F
capacitor (C2). Now
varying the light to the
phototransistor has only a
small effect on the motor
speed.
Turn on the switch (S1), the motor (M1)
spins. As you move your hand over the
phototransistor (Q4), the motor slows.
Cover the phototransistor with your hand.
The motor slows down and may stop, but
will speed up in a few seconds. Also try
shining a flashlight into the phototransistor.
!
WARNING: Moving
parts. Do not touch the
fan or motor during
operation.
Use the circuit from project 169, but replace the
phototransistor (Q4) with the microphone (X1, “+”
on top). Clap, talk loudly, or blow into the
microphone to change the motor speed.
Project 171
Delayed Speed Control (II)
Use the circuit from project 169, but swap the
locations of the phototransistor (Q4) and 5.1k
Ω
resistor (R3); put “+” on Q4 towards C4. Now
increasing the light to the phototransistor slows
down the motor, instead of speeding it up.
Project 172
Audio Delayed Speed Control
Project 173
Photo Speed Control
Turn on the switch (S1), and set the adjustable resistor (RV) so the motor (M1) just spins. Slowly
cover the phototransistor (Q4) and the motor spins faster. Place more light on the phototransistor
and the motor slows down.
!
WARNING:
Moving parts. Do
not touch the fan
or motor during
operation.
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