Play Meter

I NVERTO~
individual circuits, we need sixteen
7402 Nor gates . These 7402 Nor
gates come four per package so we
need four packages or chips .
We also need sixteen invertors.
Since 7404 invertors come six per
package, we need three packages.
Note: device L-8 has two unused
invertors.
Folowing is a complete parts list
for the comparator .
It is generally not a good idea to
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INPUT
OUTPUT
YUL
the capacitor to charge up to 2.4
volts is about one-third of a second .
So even a very quick pulse, as fast
as .0000003 seconds or 300 nano-
seconds can be recorded and the
LED wil stay on for one-third of a
second. It is very easy to see an LED
flash of one-third of a second.
PARTS LIST
CONSTRUCTION
To
16 pin I.C . Test Cl ip and Cable
Cabinet
16 Pin Socket
Alligator Clips
C.OMPARe C\~c..I.lIT~'( -
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7485 Quad Exclusive Or
7402 Quad Nor
7404 Hex Invertor
SPOT Switch
50 uf 15v Capacitor
LED
1,000 ohm Yo. watt
330 ohm Yo. watt
L 1, L2, L3, L4
L5, L7, L9, Lll
L6, L8, L 10
Sl through S16
Cl throu~h C16
01 through 016
Al through A16
A17 through A32
Figure 4 is the second half of
the schematic. This combined with
Figure 4 on page 40 of the February
Play Meter is the complete com-
parator.
Since we want to make sixteen
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use " rats nest" type wiring on test
equipment . The best possible mode
of construction of electronic gear is
to use a printed circu it board . If you
are interested in obtaining a circuit
board and / or parts to build the logic
comparator, or if you have any
questions about this or last month' s
instructions, write to me at Play
Meter.
Soon to come! Build a better test
fixture . A realistic logic probe.
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