Editing Multivibrator (section)

== History ==
[[Image:Vacuum tube multivibrator calibrating wavemeter 1920.jpg|thumb|upright=1.4|A vacuum tube Abraham-Bloch multivibrator oscillator, France, 1920 ''(small box, left)''. Its harmonics are being used to calibrate a wavemeter ''(center)''.]]

The first multivibrator circuit, the classic astable multivibrator [[electronic oscillator|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)''.  Since it produced a [[Square wave (waveform)|square wave]], in contrast to the [[sine wave]] generated by most other oscillator circuits of the time, its output contained many [[harmonic]]s above the fundamental frequency, which could be used for calibrating high frequency radio circuits.   For this reason Abraham and Bloch called it a ''multivibrateur''.   It is a predecessor of the Eccles-Jordan trigger<ref>William Henry Eccles and Frank Wilfred Jordan, "[http://v3.espacenet.com/origdoc?DB=EPODOC&IDX=GB148582&F=0&QPN=GB148582 Improvements in ionic relays]" British patent number: GB 148582 (filed: 21 June 1918; published: 5 August 1920).</ref> which was derived from the circuit a year later.

Historically, the terminology of multivibrators has been somewhat variable:
* 1942 – multivibrator implies astable: "The multivibrator circuit (Fig. 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."<ref>{{cite book
 | title = Electrical counting: with special reference to counting alpha and beta particles
 | author = Wilfred Bennett Lewis
 | publisher = CUP Archive
 | year = 1942
 | page = 68
 }}</ref>
* 1942 – multivibrator as a particular flip-flop circuit: "Such circuits were known as 'trigger' or 'flip-flop' circuits and were of very great importance. The earliest and best known of these circuits was the multivibrator."<ref>{{cite journal
 | journal = The Electrician
 | volume = 128
 | date = Feb 13, 1942
 }}</ref>
* 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."<ref>{{cite book
 | title = Time bases (scanning generators): their design and development, with notes on the cathode ray tube
 | author = Owen Standige Puckle and E. B. Moullin
 | publisher = Chapman & Hall Ltd
 | year = 1943
 | page = 51
 }}</ref>
* 1949 – monostable as flip-flop: "Monostable multivibrators have also been called 'flip-flops'."<ref>{{cite book
 | title = Waveforms
 | url = https://archive.org/details/waveforms0000chan
 | url-access = registration
 | edition = Vol. 19 of MIT Radiation Lab Series
 | author = Britton Chance
 | publisher = McGraw-Hill Book Co
 | year = 1949
 | page = [https://archive.org/details/waveforms0000chan/page/167 167]
 }}</ref>
* 1949 – monostable as flip-flop: "... a flip-flop is a monostable multivibrator and the ordinary multivibrator is an astable multivibrator."<ref>{{cite journal
 | journal = Wireless Engineer
 | title = Development of Time Bases: The Principles of Known Circuits
 | author = O. S. Puckle
 | volume = 26
 | issue = 1
 | publisher = Iliffe Electrical Publications
 | pages = 139
 | date = Jan 1949
 }}</ref>