Elenco 130-in-1 Electronics Playground - Manual (Page 95)

-95-
You know that an LED promptly lights when you turn
it on. You can also light it up gradually. In this project,
you’ll be able to observe the LEDs slowly get brighter
while you hold down the key.
This circuit arrangement is called a Miller integrating
circuit. The output of the circuit increases as its input
rises. The integrating circuit increases the value of
the 100
μF capacitor above its actual value. When
you press the key, the LEDs become brighter and the
capacitor charges slowly through resistor R. Setting
the switch to position B discharges the capacitor, and
the LEDs turn off.
Before completing the project, set the switch to
position B, to discharge the capacitor. Set the switch
to position B and hold the key down to watch LEDs
1, 2, and 3 become brighter. In about 5 seconds they
will reach maximum brightness. Now set the switch
to B to discharge the capacitor, then hold down the
key to do the experiment again.
Notes:
EXPERIMENT #76: MILLER INTEGRATING CIRCUIT
Schematic
Wiring Sequence:
31-63-122-137
32-34
35-37
38-72
71-67-116-133
68-90-115-132
69-124-119
70-121
89-138