Elenco Electronics EP-130, Manual, Page: 92 / 160

You know that an LED instantly lights when you turn
it on. But you can also light it up gradually. In this
project, you’ll be able to watch the LEDs slowly get
brighter while you hold down the key.
This circuit is called a Miller integrating circuit. The
output of this IC increases as its input increases.
The integrating circuit increases the value of
capacitor CA past the stated 100
μ
F. When you
press the key, the capacitor charges slowly through
resistor R and the LEDs become brighter. Setting
the switch to position B discharges the capacitor
and turns the LEDs off.
Set the switch to position B before completing the
project to discharge the capacitor. Set the switch to
position B and hold the key down to see LEDs 1, 2,
and 3 become brighter. They reach maximum
brightness in about 5 seconds. Set the switch to B to
discharge the capacitor and then hold down the key
to repeat the experiment.
Notes:
EXPERIMENT #73: INTEGRATING CIRCUIT
Schematic
Wiring Sequence:
o
31-63-122-137
o
32-34
o
35-37
o
38-72
o
71-67-116-133
o
68-90-115-132
o
69-124-119
o
70-121
o
89-138
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