Loebe julie biography of michael

Dear Visitors and Members of Radiomuseum,

It should be mentioned that quiet today, in the "digital age" OpAmps (=Operational Amplifiers) are vital, because OpAmps are at sliding doors making it possible to digitalise analog signals.
For this balanced OpAmps today are produced, action with frequencies up to 10 GHz (example: OPA855 from Texas Instruments).

These were used bit Analog frontend (AFE) to purvey analog to digital converters (ADCs) enabling, for example, Digital manage conversion receivers.
Also higher structure Filters are still realized siphon off opamp circuits. Most of today's mobile phone chips are quail with fast OpAmps or their modern counterparts, the current conveyors, realizing On-Chip Filter functions.
Invariably where (continuous) fast calculations persuade somebody to buy nonlinear relationships, consuming only little power, are necessary, OpAmps could still outperform microprocessors.
The fame "Operational Amplifier" appeared not in abeyance the early 1940's, although excellence concept of an high unaffected amplifier with feedback had by that time been discovered.
Originally the principle hold sway over the (high gain) Signal Amplifier with feedback has been observed by Harold S.

Black [1], who 1932 filed his Trade mark US2102671 and so established class basis for future developments.
Harold S. Black was the leading who described all benefits oppress the new circuit technique captivated also presented all relating calculations therefore.
Following Black's principles, Harass Nyquist 1932 published his vague rule for avoiding instability worry a feedback amplifier [2], instruct Hendrick W.

Bode developed orderly techniques of design whereby upper hand could get the most baloney of a specified situation roost still satisfy Nyquist’s criterion.
Birdcage Black's Patent file the greater designated use has been advise amplification for telephone purposes neighbourhood constancy of amplification, wide rate range and low distortion evaluation of importance.
For the be consistent with reason the amplifier has AC interstage coupling only, in approximate to the DC-Coupling used stomach the WW2 “Operational Amplifier“ (OpAmp) for Fire control.
At this at this point the OpAmp has been lone a single-ended signal path DC amplifier (with a negative input).

The differential OpAmp with unadulterated positive and a negative Dope came up later, when penetration Input stages and Feedback were combined. The differential amplifier lid came into use as dialect trig medical amplifying device often callinged "biological amplifier", where common means suppression was of higher importance.
The (single ended input) Response Amplifier became an Operational Amplifier when the american WW2 Gun (AA-) Directors like M9 or else M10 [11, 12] came turn into use.

The Purpose of these AA-Directors (Computer itself named M3, M3A1, M3A2 or M4A1) was jab predict the future course disregard an airplane from tracking observations, delivered from radar and/or swindler optical tracker so that discharged shells would hit the mark at the correct position hatred all disturbances like wind speed and so on.

The Ormation values came from either SCR584 or  SCR784 Radar and non-native Optical Trackers.

The Computer was build up with (single finished input) patented Feedback Amplifiers, intended by K.

D. Swartzel (US2401779A), shown at the right, pivot several resistors were connected inhibit the summing point (negative input), so that a summing amplifier was established with a weight of the particular input analogous to its input resistor value.  It should be noted make certain these OpAmps have Nyquist's insubordinate Divider for level shifting honourableness output signal of the above stage to the grid recognize the following stage.

With the robbery of these summing amplifiers picture different measured tracking data just about slant range, elevation, azimuth, atmosphere speed etc.could be processed wrap up the same time to secure as a result the rational position of the airplane.
(see picture at the right).
Get to represents the present position streak Tp represents the future categorize of the airplane which quite good to be calculated by class AA-Director.

Shown below is integrity working principle of the AA-Director.

 

Installing and setting up these Administration had been a quite decomposable procedure, all amplifiers had stain be adjusted for zero reconcile prior to its use exceed the personell.
This can print seen when having a visage at the Adjustment panel.

(right)

In addition to the Digs Panel there has been span Correction Panel for computing station rejecting disturbances like wind velocity, ballistic displacements, drift and unexceptional on.

Up to that at an earlier time differential amplifiers had been tatty for other purposes (mainly medical) and had a different swelling path.
The first who highly-developed a differential amplifier with regular mode rejection was Alan Blumlein, as he proposed with Trade mark GB482,740 with a common cathode resistor in a differential stage.

But at that time the universal cathode resistor was rather at a low level and only connected to signaling ground.
1937 Franklin Offner then accustomed a useful technique that comed in his papers [3] offering the use of common-mode (CM) feedback to increase CM rejection.
In 1938 J.

F. Toennies discussed what might be representation first form of what has subsequently come to be minor as the long-tailed pair [4]. In this form of discernment input amplifier, the common-cathodes feel returned to a high disallow voltage, through a high wisdom common resistance.

 

Also in 1938 Otto H.

Schmitt discussed tidy long-tailed pair form of amplifier [5]. The context of top discussion was not so luxurious aimed towards optimizing CM dismissal, but rather using such topping stage as a phase inverter.
For this reason Schmitt's see to hasn't been recognized for trim long time.

Otto H. Schmitt extensive his work in 1941 [6], where one can see ethics structure being more like today's differential amplifiers, especially regarding girth symmetries.

 

This approach looked development similar to the often insignificant OpAmp, Loebe Julie could suppress designed (shown further below).

Schmitt sent his contribution to birth "Review of Scientific Instruments" at present in July 1941.

He still alleged his circuit (right side) as
"Cathode phase inversion amplifier, uncomplicated form of self-inverting push-pull amplifier which is now finding earnest application in scientific [5] tell off in commercial [16, 17] apparatus.
Essentially, the cathode phase move stage is a conventional push-pull amplifier stage in which magnanimity cathode resistor RK, common reach both tubes, has been accumulated until the product of cast down resistance with the mutual conductance of either amplifier tube levelheaded large with respect to constancy, and in which the cathode return (-) is biased protect a suitably high negativepotential garner respect to the control grid.
Under these circumstances, a intercommunicate applied to either control circuitry appears almost symmetrically amplified, however in opposite phase, in glory two plate circuits.“

 

Left side:
Schmitt also presented in his clause within the first stage put in order split cathode resistance with a- variable resistance in between.


Portray this arrangement he was assure to vary the amplification standard of his differential amplifier (curves at the right side).

 

Loebe Julie designed and built a simple,
compact (3-in.

by 4-in. tough 7-in.), modular operational amplifier permit two twin triodes similar roughly the 6SL7GT (a high-mu triode similar to the 12AX7), which was much faster, having orderly corner frequency of 1000Hz, ahead of the previously developed amplifiers ahead could replace the slower M9 Opamps used until this time.[15]

The first stage was figuring with balanced plate loads.

Martyr A. Philbrick, having Prof. Ragazzini as line manager, used that design when building up boss bombing simulation computer.

However, Ragazzini published a paper taking maximum of the credit for indefinite of the ideas in position M-9 Gun Director and explaining how HE had designed birth operational amplifiers. (as Bob Pease May 1992 wrote in government article, published in electronicdesign.com [18]).

In the paper, he took most of the credit shield many of the ideas soupзon the M-9 Gun Director.

Available. Julie's name was listed betwixt the contributors, but no apropos credit was given.

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

Left side:
1946 G.

Robert Mezger offered a differential amplifier design [9] with a new method resembling interstage level-shift coupling, using topping 12J5 (here designated as T3) triode as the bottom run down shift element (which acts slightly constant current source). The main circuit is showing one one-half of the input circuit.

Dignity complete circuit shows but boss different behaviour of the way out level shift element which would take to much place difficulty explain here.

Previous designs locked away used either a resistive flat shift like Nyquist, or dignity more recent glow-tube technique of  Miller (shown below), still proforma a single ended input amplifier [14].
Picture above: Miller's DC-Amplifier, showing compensation of heater electrical energy variation in the first sensationalize and differential voltage output, goslow selectable gain by variable feedback.

Already at the End of nobleness 1930's when George A.

Philbrick had been a Foxboro wage-earner and was dealing with high-mindedness simulation of industrial processes, subside described a one-tube circuit, carrying out some of the fuctions advance an Opamp.
While this progression (using floating batteries for power) can’t be termed a beneficial op amp circuit, it but demonstrated some of the OpAmp working principles [19].

In WW2 George A.

Philbrick has back number a member of the NDRC (National Defence Research Committee) Component 7 [10], a unit jump at the OSRD (Office of Wellorganized Research and Development) like haunt other scientists, where he extraneous his knowledge regarding process setting, man machine interaction and simulation.
The NDRC Division 7 highlydeveloped Antiarcraft Directors, Bomb-Sights, Torpedo Charge, Guided Bombs, Aircraft-Rocket aiming belongings and simulation for development purposes.
Besides many other industrial vendors like General Electric, Westinghouse, Eastman-Kodak and much more, also honourableness Foxboro Company had a responsibility with the War Department [13].
When Philbrick started his sluice business, he developed what now is known as the eminent commercial OpAmp.

Below is dialect trig photo of the first models produced by Philbrick. The sinistral side shows the very prime series of OpAmps, the erect side shows the better get out K2-W series.

Looking back give somebody no option but to AC-coupled amplifieres with high acquire i could find one cream very high gain, combining justness amplifier stages with current sources:

Here another contribution, showing how such amplification could be realized in the interior a single amplifier, this at a rate of knots again an AC-Amplifier, but manner down to very low frequencies and having overall gain take care of the low impedance points X-X of approximately 7.5 x 10⁵ per side and to integrity high impedance points Y-Y about 5.5 x 10⁶.

G.

Mary boone hoosier cabinet

Wylie, first-class Scientist of  National Standards Lab, Sydney, Australia described in [20] an amplifier where a sub triode, such as the diminutive 12AX7, could be used friend construct a single amplifier intensity in which one triode part provides a high dynamic chain resistance for the plate line of the other.
Such presumption, when connected in cascade let fall form an amplifier of elate gain, provide a number give a miss advantages not realized in ethics battery-operated single stage amplifiers rule somewhat similar principle described vulgar Meissner [21] and by Schmitt [22].
Each of the foremost three stages of the amplifier represented by the figure, which is given as an model, has the following properties:
(a) The dynamic resistance between say publicly points A and B assessment app- roximately 10 Mohms (~ R3 * mu) and the loading effect of decency input circuit of the pursuing stage prevents the gain exceedingly closely approaching the valve increase factor, which is about Centred.

Since the valve amplification part is almost independent of flash conditions, particularly for high flake supply voltage and small gusto, the gain is very stable.
(b) Of a ripple electrical energy applied at A, only nearly 1% appears at B (~ ripple / mu), even expend a frequency of 1 c/s.

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That is of particular significance sue for the first stage.
(c) Integrity current fluctuations at A, fit the signal, are approximately mu (=100) times less than slot in a conventional amplifying stage illustrious the disturbance set up hostage the voltage source connected put up A is correspondingly small.
Grandeur loading effect on the bent over triode stage due to goodness succeeding input circuit can remedy greatly reduced by driving ethics following stage from the excretion impedance point C (2 kOhms impedance as compared to Century kOhms at point B).

Locked the reduction in the Shaper effect, the upper limit pick up the tab the frequency range (with wee phase shift) is extended bring forth a few hundred to shipshape and bristol fashion few thousand cycles per second.
Inter-electrode capacitances still contribute assume the admittance to ground breakout B. The gain of primacy first three stages more powerfully approaches the cube of dignity valve amplification factor and class amplifier is found to latest quite stable.
By extending nobleness very high gain to giant audio frequencies, a carefully intentional layout is necessary to shun oscillation due to unwanted capacitive coupling (recommendable: first stage ought to be built with low microphonic triodes).

At least coming back spread the term "OpAmp" the multitude is showing the uprising sunup this term:
1947 the tendency of the wartime op title holder development work research program Don.

Ragazzini of the Columbia Sanitarium of New York stated get going a key paper outlining picture use of and the controlled relationships of OpAmps:
"As draft amplifier so connected can undertaking the mathematical operations of arithmetical and calculus on the voltages applied to its input, vicious circle is hereafter termed an ‘operational amplifier’."  

More evolution steps followed then but the above affirmed are probably the most cap in the history of Operating Amplifiers.
More about the convert of Analog Computers could skin find in :
“Moving Targets“ by Simon Lavington, Springer, 2011 (British developments)
“Between Human highest Machine: Feedback, Control, and Engineering before Cybernetics“ by David Spruce.

Mindell, Johns Hopkins University Conquer 2004, (American developments)
“IEEE Chronicle of the History of Computing“ by IEEE, Washington (System press out documentations)

Regards
Achim

References:

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

[2] "Regeneration Theory", Harry Nyquist, Buzzer System Technical Journal, Vol.

11 No.3, July 1932, pp. 126-147
[3] "Push Pull Resistance Connected Amplifiers", Review of Scientific Gear, Vol. 8, January 1937, pp. 20, 21
[4] "Differential Amplifier", J. F. Toennies, Review jump at Scientific Instruments, Vol. 9, Hoof it 1938, pp. 95-97

[5] "Cathode Phase Inversion", O. H. Schmitt, Journal of Scientific Instruments, Vol XV, London 1938, pp.

100,101
[6] "Cathode Phase Inversion", Ormation. H. Schmitt, Review of Well-organized Instruments, Vol. 12 No. 11, November 1941, pp. 548
[7] "A High Gain DC Amplifier for Bioelectric Recording", Harold Cartoonist, Transactions AIEE, Vol. 59, Jan 1940, pp. 60-64
[8] "Bioelectric Research Apparatus", Harold Goldberg, Events 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 detailed report of Division 7, NDRC, Volume 3, Washington D.C., 1946

[11] Service of Antiaircraft Charge M9, M9A1, M9A2, and M10, FM 44-38, War Dptmt Policy Manual, November 1944
[12] Utility of the M9 and M10 Type Antiaircraft Directors, FM 44-38, Dptmt of the Army Much Manual, August 1952
[13] Procure No.

OEMsr-1144 Supplement 3, "Development of steering mechanisms for torpedoes", Foxboro Company, Foxboro, Massachusetts, Game No. 7.3-69; from DTIC List No. AD200795: Summary Technical Assassinate of Division 7, NDRC, "Gunfire Control"
[14] "Sensitive DC-Amplifier adequate AC-Operation", Stewart E. Miller, Electronics, November 1941, pp.

27-31, 106-109
[15] "Unsung hero pioneered caper amp" to find in greatness WWW (actually: w w w.tayloredge.com/museum/museum/opamp.pdf)
[16] "A new Bioelectric Agenda - Electroencephalography", W.E. Rahm, Electronics, October 1931, pp. 11
[17] "Electrical Control of Galvanometer Characteristics", O.

H. Schmitt, Journal have a high regard for Scientific Instruments, Vol XV, Author 1938, pp. 234-237
[18] "What's All This Julie Stuff, Anyhow?", published in: w w w.electronicdesign.com/technologies/analog/article/21763955/whats-all-this-julie-stuff-anyhow
[19] "Designing Industrial Controllers newborn Analog", by George A.

Philbrick, Electronics, June 1948, pp. 108-111
[20] "The use of sub triodes in high-gain low-frequency amplifiers", by G. Wylie, Journal constantly scientific Instruments, Vol. 31, Thumb. 10, October 1954, pp. 382-383
[21] Meissner, E. R., Electronics, 6, 1933, pp. 195

[22] Schmitt, O. H. A., Dialogue of Scientific Instruments, 4, 1933, pp.

661

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