1949 – monostable as flip-flop: "Monostable multivibrators have also been called 'flip-flops'.".1943 – flip-flop as one-shot pulse generator: ".an essential difference between the two-valve flip-flop and the multivibrator is that the flip-flop has one of the valves biased to cutoff.".The earliest and best known of these circuits was the multivibrator." 1942 – multivibrator as a particular flip-flop circuit: "Such circuits were known as 'trigger' or 'flip-flop' circuits and were of very great importance.7-6) is somewhat similar to the flip-flop circuit, but the coupling from the anode of one valve to the grid of the other is by a condenser only, so that the coupling is not maintained in the steady state." 1942 – multivibrator implies astable: "The multivibrator circuit (Fig.
Historically, the terminology of multivibrators has been somewhat variable: It is a predecessor of the Eccles-Jordan trigger which was derived from the circuit a year later. For this reason Abraham and Bloch called it a multivibrateur. Since it produced a square wave, in contrast to the sine wave generated by most other oscillator circuits of the time, its output contained many harmonics above the fundamental frequency, which could be used for calibrating high frequency radio circuits. The first multivibrator circuit, the classic astable multivibrator oscillator (also called a plate-coupled multivibrator) was first described by Henri Abraham and Eugene Bloch in Publication 27 of the French Ministère de la Guerre, and in Annales de Physique 12, 252 (1919). Its harmonics are being used to calibrate a wavemeter (center). Other applications included early television systems, where the various line and frame frequencies were kept synchronized by pulses included in the video signal.Ī vacuum tube Abraham-Bloch multivibrator oscillator, France, 1920 (small box, left). This technique was used in early electronic organs, to keep notes of different octaves accurately in tune. A free-running multivibrator with a frequency of one-half to one-tenth of the reference frequency would accurately lock to the reference frequency. For example, before the advent of low-cost integrated circuits, chains of multivibrators found use as frequency dividers. Multivibrators find applications in a variety of systems where square waves or timed intervals are required. It can store one bit of information, and is widely used in digital logic and computer memory. It can be flipped from one state to the other by an external trigger pulse. Bistable multivibrator, in which the circuit is stable in either state.This circuit is also known as a one shot. Such a circuit is useful for creating a timing period of fixed duration in response to some external event. After entering the unstable state, the circuit will return to the stable state after a set time. A trigger pulse causes the circuit to enter the unstable state. Monostable multivibrator, in which one of the states is stable, but the other state is unstable (transient).Astable multivibrator, in which the circuit is not stable in either state -it continually switches from one state to the other.Original vacuum tube Abraham-Bloch multivibrator oscillator, from their 1919 paper
0 kommentar(er)
