Elenco Electronic Playground 50-in-1 Experiments - Manual (Page 67)

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Now let’s add on to the previous circuit by adding the
wires listed in the Wiring Checklist (these are in addition
to the wires from Experiment 47, which you should still
have assembled).
Test the four
combinations of X
and Y as before to
determine the state
of LED2 (ON or
OFF), filling in the
table at right:
This table shows that if neither X nor Y is HIGH then
LED2 is ON. Hence, this configuration is called a NOR
gate. X and Y might represent your burglar alarm and
flood detector, so if neither X nor Y is on then your “all
clear” light goes on. You may also think of this as adding
a NOT gate to an OR gate to
produce a NOR gate. A NOT gate
is just the opposite of its input:
Gates such as OR, NOR, and NOT form some of the
basic building blocks for computers. The combinations of
resistors and transistors shown here to build them are a
form of Resistor-Transistor-Logic, which was used
extensively in early generations of computers and which
led to the development of many of today’s logic families.
These basic gates are so commonly used that they have
their own symbols:
EXPERIMENT #48: Neither This NOR That
Wiring Checklist (additions to
Experiment 47 Checklist):
o 14-to-26
o 40-to-3
o 4-to-13
o 12-to-51
o 41-to-43
o 19-to-52
Wire X
Wire Y
X Y LED 2
LOW LOW
LOW HIGH
HIGH LOW
HIGH HIGH
Input NOT
LOW HIGH
HIGH LOW
OR Gate NOR Gate NOT Gate
Schematic