Manual

-54-
R-S does not mean Radio Shack
®
flip-flop. As we
mentioned earlier circuits that flip-flop alternate
b
etween two states. Those who use flip-flop circuits
m
ost often are engineers, and they use flip-flop
circuits to switch between low (0) and high (1)
outputs. We say a circuit is at set status (S) when
the output is high or on. We use the word rest (R)
when a circuit is off.
Once you have completed the wiring, to turn the
power on turn the switch to A. LED 1 or LED 2 will
light up. Touch terminals 13 and 14 in turn with the
long wire connected to terminal 26. What occurs to
LED 1 and LED 2?
The R-S flip-flop is set when the LED 2 lights. The
R-S flip flop is in reset when the LED 1 lights. Set or
reset the flip-flop, then remove the long wire from
the circuit and see what it does.
Now you can observe one of the primary
characteristics of the R-S flip flop. Once you have
the circuit either set or reset, the circuit stays in the
specific state until an input signal causes it to
change. This means that R-S flip flop can remember
things. Advanced computers use similar circuits to
remember things.
Notes:
EXPERIMENT #38: “R-S FLIP-FLOP” USING TTL
Wiring Sequence:
o 77-75-49-31-34-131
o 33-53-52
o 36-55-51
o 50-76-13 (SET)
o 54-78-14 (RESET)
o 121-62-60-59-57-56-LONG WIRE
o 119-132
Schematic
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