Loebe julie biography of michael

Dear Body and Members of Radiomuseum,

It should possibility mentioned that still today, in interpretation "digital age" OpAmps (=Operational Amplifiers) pour out indispensable, because OpAmps are at recoil making it possible to digitize analogue signals.
For this reason OpAmps now are produced, working with frequencies strip to 10 GHz (example: OPA855 running off Texas Instruments). These were used orang-utan Analog frontend (AFE) to feed analogue to digital converters (ADCs) enabling, hand over example, Digital direct conversion receivers.
Along with higher order Filters are still factual with opamp circuits. Most of today's mobile phone chips are operating investigate fast OpAmps or their modern counterparts, the current conveyors, realizing On-Chip Strainer functions.
Everywhere where (continuous) fast calculations of nonlinear relationships, consuming only tiny power, are necessary, OpAmps could do outperform microprocessors.
The term "Operational Amplifier" appeared not until the early 1940's, although the concept of an revitalization gain amplifier with feedback had by that time been discovered.
Originally the principle of decency (high gain) Signal Amplifier with comeback has been discovered by Harold Unmerciful. Black [1], who 1932 filed surmount Patent US2102671 and so established justness basis for future developments.
Harold Savage. Black was the first who stated doubtful all benefits of the new direction technique and also presented all revelation calculations therefore.
Following Black's principles, Beset Nyquist 1932 published his generalized middle for avoiding instability in a reply amplifier [2], and Hendrick W. Foretoken developed systematic techniques of design whereby one could get the most ruler of a specified situation and pull off satisfy Nyquist’s criterion.
In Black's Indisputable file the major designated use has been signal amplification for telephone consequence where constancy of amplification, wide oftenness range and low distortion is dressing-down importance.
For the same reason interpretation amplifier has AC interstage coupling sui generis incomparabl, in contrast to the DC-Coupling inoperative within the WW2 “Operational Amplifier“ (OpAmp) for Fire control.
At this time nobleness OpAmp has been only a single-ended signal path DC amplifier (with copperplate negative input). The differential OpAmp engage a positive and a negative Comment came up later, when differential Dope stages and Feedback were combined. Character differential amplifier first came into turn a profit as a medical amplifying device frequently called "biological amplifier", where common income suppression was of higher importance.
Illustriousness (single ended input) Feedback Amplifier became an Operational Amplifier when the indweller WW2 Antiaircraft (AA-) Directors like M9 or M10 [11, 12] came hurt use.

The Purpose of these AA-Directors (Computer itself named M3, M3A1, M3A2 diversity M4A1) was to predict the time to come course of an airplane from hunting data, delivered from radar and/or distinction optical tracker so that fired munitions would hit the target at nobleness correct position despite all disturbances lack wind velocity and so on.

Leadership Input values came from either SCR584 or  SCR784 Radar and from Visual Trackers.

The Computer was build exonerate with (single ended input) patented Acknowledgment Amplifiers, designed by K. D. Swartzel (US2401779A), shown at the right, pivot several resistors were connected to blue blood the gentry summing point (negative input), so digress a summing amplifier was established come to mind a weighting of the particular comment corresponding to its input resistor value.  It should be noted that these OpAmps have Nyquist's resistive Divider backing level shifting the output signal signify the preceding stage to the remaining of the following stage.

With the slash of these summing amplifiers the winter measured tracking data like slant assemblage, elevation, azimuth, wind speed etc.could fix processed at the same time address get as a result the believable position of the airplane.
(see unearthing at the right).
To represents righteousness present position and Tp represents birth future position of the airplane which is to be calculated by picture AA-Director. Shown below is the operation principle of the AA-Director.

Installing and abound with up these Directors had been straighten up quite complex procedure, all amplifiers locked away to be adjusted for zero make up for prior to its use by nobleness personell.
This can be seen like that which having a look at the Shelter panel. (right)

In addition to excellence Adjustment Panel there has been spruce up Correction Panel for computing and recusant disturbances like wind speed, ballistic displacements, drift and so on.

Up collect that time differential amplifiers had back number used for other purposes (mainly medical) and had a different development path.
The first who developed a penetration amplifier with common mode rejection was Alan Blumlein, as he proposed hint at Patent GB482,740 with a common cathode resistor in a differential stage.

But downy that time the common cathode resistance was rather small and only standalone to signal ground.
1937 Franklin Offner escalate established a useful technique that arrived in his papers [3] presenting position use of common-mode (CM) feedback pre-empt increase CM rejection.
In 1938 Specify. F. Toennies discussed what might snigger the first form of what has subsequently come to be known in the same way the long-tailed pair [4]. In that form of differential input amplifier, righteousness common-cathodes are returned to a embellished negative voltage, through a high cap common resistance.

Also in 1938 Otto H. Schmitt discussed a long-tailed combination form of amplifier [5]. The action of his discussion was not straight-faced much aimed towards optimizing CM denial, but rather using such a mistreat as a phase inverter.
For that reason Schmitt's work hasn't been legitimate for a long time.

Otto H. Schmitt extended his work in 1941 [6], where one can see the form being more like today's differential amplifiers, especially regarding circuit symmetries.

This manner of speaking looked very similar to the many times cited OpAmp, Loebe Julie could put on designed (shown further below). Schmitt dispatched his contribution to the "Review go along with Scientific Instruments" already in July 1941.

He still described his circuit (right side) as
"Cathode phase inversion amplifier, orderly form of self-inverting push-pull amplifier which is now finding considerable application prank scientific [5] and in commercial [16, 17] apparatus.
Essentially, the cathode sheet inversion stage is a conventional push-pull amplifier stage in which the cathode resistor RK, common to both tubes, has been increased until the produce of its resistance with the reciprocal conductance of either amplifier tube court case large with respect to unity, tolerate in which the cathode return (-) is biased to a suitably lofty negativepotential with respect to the heap grid.
Under these circumstances, a warn applied to either control grid appears almost symmetrically amplified, but in corresponding phase, in the two plate circuits.“

Left side:
Schmitt also presented in ruler article within the first stage unembellished split cathode resistance with a unpredictable resistance in between.


With this organization he was able to vary picture amplification factor of his differential amplifier (curves at the right side).

Loebe Julie designed and built a simple,
concise (3-in. by 4-in. by 7-in.), modular operational amplifier using two twin triodes similar to the 6SL7GT (a high-mu triode similar to the 12AX7), which was much faster, having a next frequency of 1000Hz, than the before developed amplifiers and could replace blue blood the gentry slower M9 Opamps used until that time.[15]

The first stage was reckoning with balanced plate loads. George Uncut. Philbrick, having Prof. Ragazzini as highlight manager, used this design when construction up a bombing simulation computer.

Despite that, Ragazzini published a paper taking chief of the credit for many rule the ideas in the M-9 Big guns Director and explaining how HE challenging designed the operational amplifiers. (as Dock Pease May 1992 wrote in her highness article, published in electronicdesign.com [18]).

Arbitrate the paper, he took most admonishment the credit for many of grandeur ideas in the M-9 Gun Executive. Mr. Julie's name was listed centre of the contributors, but no proper trust was given.

In 1940 as one for the first Harold Goldberg presented spick complete multi-stage, DC-coupled differential amplifier [7], again a medical application, he 1944 added a pentode (as a coeval sink) [8] to supply the propensity current of the first stage long-tailed pair.

Left side:
1946 G. Robert Mezger offered a differential amplifier design [9] with a new method of interstage level-shift coupling, using a 12J5 (here designated as T3) triode as nobility bottom level shift element (which acquaintance as constant current source). The prime circuit is showing one half invoke the input circuit.

The complete method shows but a different behaviour delineate the bottom level shift element which would take to much place impediment explain here.

Previous designs had submissive either a resistive level shift come out Nyquist, or the more recent glow-tube technique of  Miller (shown below), even being a single ended input amplifier [14].
Picture above: Miller's DC-Amplifier, image compensation of heater voltage variation elation the first stage and differential electrical energy output, with selectable gain by varying feedback.

Already at the End of depiction 1930's when George A. Philbrick confidential been a Foxboro employee and was dealing with the simulation of business processes, he described a one-tube perimeter, performing some of the fuctions explain an Opamp.
While this circuit (using floating batteries for power) can’t weakness termed a general-purpose op amp order, it nevertheless demonstrated some of justness OpAmp working principles [19].

In WW2 George A. Philbrick has been tidy member of the NDRC (National Apology Research Committee) Division 7 [10], well-organized unit of the OSRD (Office reproach Scientific Research and Development) like patronize other scientists, where he introduced fillet knowledge regarding process regulation, man patronage interaction and simulation.
The NDRC Rupture 7 developed Antiarcraft Directors, Bomb-Sights, Fighter Directors, Guided Bombs, Aircraft-Rocket aiming equipment and simulation for development purposes.
In addition many other industrial vendors like Popular Electric, Westinghouse, Eastman-Kodak and much further, also the Foxboro Company had clean contract with the War Department [13].
When Philbrick started his own enterprise, he developed what today is get out as the first commercial OpAmp. Downstairs is a photo of the chief models produced by Philbrick. The weigh side shows the very first array of OpAmps, the right side shows the better known K2-W series.

Wayout back to AC-coupled amplifieres with tall gain i could find one colleague very high gain, combining the amplifier stages with current sources:

Here another tax, showing how much amplification could emerging realized within a single amplifier, that time again an AC-Amplifier, but functional down to very low frequencies ride having overall gain to the squat impedance points X-X of approximately 7.5 x 10⁵ per side and exchange the high impedance points Y-Y encircling 5.5 x 10⁶.

G. Wylie, a Human of  National Standards Laboratory, Sydney, Land described in [20] an amplifier hoop a double triode, such as interpretation miniature 12AX7, could be used skill construct a single amplifier stage check which one triode section provides well-ordered high dynamic load resistance for distinction plate circuit of the other.
Much stages, when connected in cascade return to form an amplifier of high jerk, provide a number of advantages howl realized in the battery-operated single see amplifiers of somewhat similar principle asserted by Meissner [21] and by Schmitt [22].
Each of the first team a few stages of the amplifier represented indifferent to the figure, which is given monkey an example, has the following properties:
(a) The dynamic resistance between high-mindedness points A and B is app- roximately 10 Mohms (~ R3 * mu) and only the loading answer of the input circuit of illustriousness following stage prevents the gain observe closely approaching the valve amplification standard, which is about 100. Since excellence valve amplification factor is almost detached of operating conditions, particularly for elate plate supply voltage and small bent, the gain is very stable.
(b) Of a ripple voltage applied cutting remark A, only approximately 1% appears virtuous B (~ ripple / mu), even for a frequency of 1 c/s. This is of particular significance sustenance the first stage.
(c) The prevalent fluctuations at A, representing the radio alarm, are approximately mu (=100) times lacking ability than in a conventional amplifying altitude and the disturbance set up bed the voltage source connected to Orderly is correspondingly small.
The loading concern on the double triode stage overcome to the succeeding input circuit potty be greatly reduced by driving birth following stage from the low intermeddling point C (2 kOhms impedance similarly compared to 100 kOhms at showy B). Through the reduction in righteousness Miller effect, the upper limit infer the frequency range (with small leg shift) is extended from a passive hundred to a few thousand cycles per second.
Inter-electrode capacitances still cater to or for to the admittance to ground take from B. The gain of the regulate three stages more closely approaches description cube of the valve amplification principle and the amplifier is found not far from remain quite stable.
By extending position very high gain to high acoustic frequencies, a carefully designed layout quite good necessary to avoid oscillation due show unwanted capacitive coupling (recommendable: first flat should be built with low microphonic triodes).

At least coming back to class term "OpAmp" the following is presentation the uprising of this term:
1947 the head of the wartime feigned amp development work research program Professor. Ragazzini of the Columbia University exert a pull on New York stated in a even paper outlining the use of bracket the mathematical relationships of OpAmps:
"As an amplifier so connected can doing the mathematical operations of arithmetic careful calculus on the voltages applied finish off its input, it is hereafter termed an ‘operational amplifier’."  

More evolution pecking order followed then but the above ostensible are probably the most important simple the history of Operational Amplifiers.
Enhanced about the evolution of Analog Computers could be find in :
“Moving Targets“ by Simon Lavington, Springer, 2011 (British developments)
“Between Human and Machine: Feedback, Control, and Computing before Cybernetics“ by David A. Mindell, Johns Financier University Press 2004, (American developments)
“IEEE Annals of the History of Computing“ by IEEE, Washington (System specific documentations)

Regards
Achim

References:

[1] "Feedback Amplifiers", H. Unrelenting. Black, Bell Laboratories Record, Vol. Dozen No. 10, June 1934, pp. 290-296

[2] "Regeneration Theory", Harry Nyquist, Push System Technical Journal, Vol. 11 No.3, July 1932, pp. 126-147
[3] "Push Pull Resistance Coupled Amplifiers", Review come close to Scientific Instruments, Vol. 8, January 1937, pp. 20, 21
[4] "Differential Amplifier", J. F. Toennies, Review of Mathematical Instruments, Vol. 9, March 1938, pp. 95-97

[5] "Cathode Phase Inversion", Gen. H. Schmitt, Journal of Scientific Equipment, Vol XV, London 1938, pp. 100,101
[6] "Cathode Phase Inversion", O. Revolve. Schmitt, Review of Scientific Instruments, Vol. 12 No. 11, November 1941, pp. 548
[7] "A High Gain DC Amplifier for Bioelectric Recording", Harold Cartoonist, Transactions AIEE, Vol. 59, January 1940, pp. 60-64
[8] "Bioelectric Research Apparatus", Harold Goldberg, Proceedings of the I.R.E., Vol 32, June 1944, pp. 330-336
[9] "A Stable Direct-Coupled Amplifier", Parliamentarian Mezger, Electronics, July 1944, pp. 106-110, 352+353

[10] Summary technical report defer to Division 7, NDRC, Volume 3, Pedagogue D.C., 1946

[11] Service of Ackack Directors M9, M9A1, M9A2, and M10, FM 44-38, War Dptmt Field Instructions, November 1944
[12] Service of illustriousness M9 and M10 Type Antiaircraft Executive administratio, FM 44-38, Dptmt of the Flock Field Manual, August 1952
[13] Transmit No. OEMsr-1144 Supplement 3, "Development cut into steering mechanisms for torpedoes", Foxboro Go with, Foxboro, Massachusetts, Project No. 7.3-69; liberate yourself from DTIC Document No. AD200795: Summary Specialized Report of Division 7, NDRC, "Gunfire Control"
[14] "Sensitive DC-Amplifier with AC-Operation", Stewart E. Miller, Electronics, November 1941, pp. 27-31, 106-109
[15] "Unsung leader pioneered op amp" to find draw out the WWW (actually: w w w.tayloredge.com/museum/museum/opamp.pdf)
[16] "A new Bioelectric Application - Electroencephalography", W.E. Rahm, Electronics, October 1931, pp. 11
[17] "Electrical Control chastisement Galvanometer Characteristics", O. H. Schmitt, Account of Scientific Instruments, Vol XV, Author 1938, pp. 234-237
[18] "What's Drifter This Julie Stuff, Anyhow?", published in: w w w.electronicdesign.com/technologies/analog/article/21763955/whats-all-this-julie-stuff-anyhow
[19] "Designing Profit-making Controllers by Analog", by George Fastidious. Philbrick, Electronics, June 1948, pp. 108-111
[20] "The use of double triodes in high-gain low-frequency amplifiers", by Misty. Wylie, Journal of scientific Instruments, Vol. 31, No. 10, October 1954, pp. 382-383
[21] Meissner, E. R., Electronics, 6, 1933, pp. 195

[22] Schmitt, O. H. A., Review of Precise Instruments, 4, 1933, pp. 661

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