Elenco Electronics EP-130, Руководство пользователя

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Our last project had a characteristic that could be a
problem in some situations. LEDs 1 and 2 take turns
lighting and turning off. We might want both LEDs to
light and turn off together. Did you figure out how to
make the LEDs do this when you experimented with
the last project? This circuit shows you how.
If you look carefully at the schematic for this project
and the schematic for the last project, you will find
they are almost identical. The only change is the
addition of another NAND gate circuit.
As in our last project, setting the switch to B blocks
the channel from LED 1 to LED 2. But when you set
the switch to A, you’ll see LED 2 light and turn off at
the same time at LED 1. The two NAND gates make
up an AND gate (remember this circuit from Project
36 (“TTL “AND” GATE’)).
In this circuit, LED 1 is called the data input. LED 2
is called the output. These terms are often used with
enable circuits. They will pop up from time to time
when we talk about digital electronics.
You might suspect by now that we can use other
digital circuits to perform enable functions. Can you
figure out how? Be sure to keep notes of our
findings, especially if you figure out how to use an
OR gate in an enable circuit. (You’ll see why in the
project.)
Notes:
EXPERIMENT #41: TTL “AND” ENABLE CIRCUIT
Wiring Sequence:
o
13-49-42-45-131
o
14-119
o
71-50-31-44-114
o
86-82-80-72-56-57-59-60-62-33-36-121-133
o
34-55
o
40-113-85
o
41-116-79
o
43-115-81
o
51-132
o
52-53-54
o
13-14 (POWER)
Schematic