Elenco Electronics 202 - Manual (Page 85)

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Project #195 Storing Electricity
OBJECTIVE: To store electricity in a capacitor.
Project #196 Lamp Brightness Control
OBJECTIVE:
To use a transistor combination to
control a lamp.
OBJECTIVE: To make an
electric fan using a transistor
circuit.
Use the circuit from project #196.
Replace one battery holder (B1) with
a 3-snap, then replace the lamp (L2)
with the motor (M1) and install the fan.
Make sure you connect the motor with
the positive (+) side on E4, not G4. By
controlling the adjustable resistor
(RV), the speed of the fan changes.
Now you can make your own speed-
changing electric fan.
Here is a combination with two
transistors (Q1 & Q2). This
combination increases the amplifying
power. By changing the resistance,
the current at the base of the
transistor is also changed. With this
amplifying ability of the combination,
there is a greater change of current to
the lamp (L2). This changes the
brightness.
Turn the slide switch (S1) on and connect points A & B with a 2-snap
wire. The green LED (D2) will flash and the 470
μF capacitor (C5) will
be charged with electricity. The electricity is now stored in the
capacitor. Disconnect points A & B. Connect points B & C and there
will be a flash from the 6V lamp (L2).
The capacitor discharges through the resistor (R1) to the base of the
NPN transistor (Q2). The positive current turns on the transistor like a
switch, connecting the lamp to the negative (–) side of the batteries.
The light will go out after the capacitor discharges, because there is no
more current at the base of the transistor.
Project #197
Electric Fan
!
WARNING: Moving parts.
Do not touch the fan or
motor during operation.