Elenco Electronics EP-130, Manual, Page: 60 / 160

-60-
No, R-S does not mean Radio Shack ® flip-flop. As
we mentioned, earlier, flip-flop circuits are circuits
that alternate between two states. Engineers often
use flip-flop circuits to switch between high (1) and
low (0) outputs. When the output is high, or on, we
say the circuit is at set status (S). When it is off, we
say it is at rest (R). This explains where the R-S flip-
flop circuit got its name.
After you finish the wiring, turn the switch to A to
turn on the power. Either LED 1 or LED 2 lights. Take
the long wire connected to terminal 56 and touch
terminals 13 and 14 in turn. What happens to LED 1
and LED 2?
When LED 2 lights, the R-S flip-flop is in the set
state. When LED 1 lights, the R-S Flip-flop is reset.
After you set or reset the flip-flop, remove the long
wire from the circuit and see what happens.
Now you can see one of the prime characteristics of
the R-S flip-flop. Once the circuit is set or reset, the
circuit keeps that state until an input signal causes it
to change. This means the R-S flip-flop can
remember things. Advanced computers use circuits
similar to this one so they can remember things as
well.
Notes:
EXPERIMENT #44: TTL “R-S FLIP-FLOP”
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