flip-flop circuit[′flip‚fläp ‚sər·kət]
a term used in pulse engineering to denote a device possessing two or, less often, several steady states and capable of changing abruptly from one state to another. The abrupt change of state is an externally initiated response due to avalanche-type processes, which develop in the circuit as a consequence of the strong positive feedback. The external pulse is a trigger, or tripping pulse; the change of state occurs whenever this pulse reaches a level called the trigger level. The active elements in a flip-flop circuit include electron and discharge tubes, transistors, and tunnel diodes. The circuit for the aperiodic electron-tube amplifier with a positive feedback loop that was designed by M. D. Bonch-Bruevich in 1918 is a classic example of an electronic flip-flop circuit. The most commonly employed flipflop circuit in automated equipment and computer technology is the trigger circuit.