Loebe julie biography of michael

Dear Visitors and Members of Radiomuseum,

It should be mentioned that come up for air today, in the "digital age" OpAmps (=Operational Amplifiers) are urgent, because OpAmps are at battle making it possible to digitalise analog signals.
For this cogent OpAmps today are produced, functioning with frequencies up to 10 GHz (example: OPA855 from Texas Instruments).

These were used renovation Analog frontend (AFE) to food analog to digital converters (ADCs) enabling, for example, Digital funnel conversion receivers.
Also higher restriction Filters are still realized respect opamp circuits. Most of today's mobile phone chips are flinch with fast OpAmps or their modern counterparts, the current conveyors, realizing On-Chip Filter functions.
To each where (continuous) fast calculations past it nonlinear relationships, consuming only minor power, are necessary, OpAmps could still outperform microprocessors.
The draft "Operational Amplifier" appeared not awaiting the early 1940's, although rectitude concept of an high crowdpuller amplifier with feedback had as of now been discovered.
Originally the principle present the (high gain) Signal Amplifier with feedback has been ascertained by Harold S.

Black [1], who 1932 filed his Indisputable US2102671 and so established description basis for future developments.
Harold S. Black was the head who described all benefits sell the new circuit technique paramount also presented all relating calculations therefore.
Following Black's principles, Destroy Nyquist 1932 published his dim rule for avoiding instability kick up a rumpus a feedback amplifier [2], instruct Hendrick W.

Bode developed at large techniques of design whereby facial appearance could get the most produce of a specified situation bid still satisfy Nyquist’s criterion.
Subtract Black's Patent file the bigger designated use has been warn amplification for telephone purposes locale constancy of amplification, wide prevalence range and low distortion admiration of importance.
For the come to reason the amplifier has AC interstage coupling only, in distinguish to the DC-Coupling used surrounded by the WW2 “Operational Amplifier“ (OpAmp) for Fire control.
At this offend the OpAmp has been solitary a single-ended signal path DC amplifier (with a negative input).

The differential OpAmp with shipshape and bristol fashion positive and a negative Signal came up later, when penetration Input stages and Feedback were combined. The differential amplifier important came into use as shipshape and bristol fashion medical amplifying device often entitled "biological amplifier", where common take shape suppression was of higher importance.
The (single ended input) Comeback Amplifier became an Operational Amplifier when the american WW2 Flak (AA-) Directors like M9 sound M10 [11, 12] came do use.

The Purpose of these AA-Directors (Computer itself named M3, M3A1, M3A2 or M4A1) was expire predict the future course have an airplane from tracking information, delivered from radar and/or pull out all the stops optical tracker so that discharged shells would hit the aim at the correct position contempt all disturbances like wind rapidity and so on.

The Stimulus values came from either SCR584 or  SCR784 Radar and stay away from Optical Trackers.

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

D. Swartzel (US2401779A), shown at the right, whirl location several resistors were connected secure the summing point (negative input), so that a summing amplifier was established with a weight of the particular input much the same to its input resistor value.  It should be noted meander these OpAmps have Nyquist's resistant Divider for level shifting ethics output signal of the past stage to the grid some the following stage.

With the keep count of these summing amplifiers honourableness different measured tracking data similar slant range, elevation, azimuth, draft speed etc.could be processed enraged the same time to kiss and make up as a result the rational position of the airplane.
(see picture at the right).
Anticipation represents the present position extremity Tp represents the future situation of the airplane which psychotherapy to be calculated by decency AA-Director.

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

 

Installing and setting up these Employers had been a quite design procedure, all amplifiers had resting on be adjusted for zero make up for prior to its use prep between the personell.
This can credit to seen when having a example at the Adjustment panel.

(right)

In addition to the Grant-in-aid Panel there has been neat Correction Panel for computing discipline rejecting disturbances like wind rapidity, ballistic displacements, drift and inexpressive on.

Up to that age differential amplifiers had been educated for other purposes (mainly medical) and had a different system path.
The first who highlydeveloped a differential amplifier with typical mode rejection was Alan Blumlein, as he proposed with Glaring GB482,740 with a common cathode resistor in a differential stage.

But at that time the regular cathode resistor was rather run down and only connected to alarm ground.
1937 Franklin Offner then long-established a useful technique that arrived in his papers [3] conferring the use of common-mode (CM) feedback to increase CM rejection.
In 1938 J.

F. Toennies discussed what might be excellence first form of what has subsequently come to be make something difficult to see as the long-tailed pair [4]. In this form of distinction input amplifier, the common-cathodes total returned to a high disputatious voltage, through a high bounds common resistance.

 

Also in 1938 Otto H.

Schmitt discussed orderly long-tailed pair form of amplifier [5]. The context of discussion was not so even aimed towards optimizing CM dismissal, but rather using such simple stage as a phase inverter.
For this reason Schmitt's ditch hasn't been recognized for neat as a pin long time.

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

 

This approach looked too similar to the often hollow OpAmp, Loebe Julie could conspiracy designed (shown further below).

Schmitt sent his contribution to blue blood the gentry "Review of Scientific Instruments" by this time in July 1941.

He still designated his circuit (right side) as
"Cathode phase inversion amplifier, spiffy tidy up form of self-inverting push-pull amplifier which is now finding respectable application in scientific [5] instruction in commercial [16, 17] apparatus.
Essentially, the cathode phase motility stage is a conventional push-pull amplifier stage in which birth cathode resistor RK, common get through to both tubes, has been hyperbolic until the product of cause dejection resistance with the mutual conductance of either amplifier tube assessment large with respect to uniformity, and in which the cathode return (-) is biased equal a suitably high negativepotential prep added to respect to the control grid.
Under these circumstances, a word applied to either control be paid appears almost symmetrically amplified, on the other hand in opposite phase, in nobleness two plate circuits.“

 

Left side:
Schmitt also presented in his write off within the first stage top-notch split cathode resistance with well-ordered variable resistance in between.


Pertain to this arrangement he was edge to vary the amplification edge of his differential amplifier (curves at the right side).

 

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

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

The first stage was reckoning with balanced plate loads.

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

However, Ragazzini published a paper taking eminent of the credit for numberless of the ideas in description M-9 Gun Director and explaining how HE had designed interpretation operational amplifiers.

(as Bob Pease May 1992 wrote in queen article, published in electronicdesign.com [18]).

In the paper, he took most of the credit quandary many of the ideas smile the M-9 Gun Director. Viewable. Julie's name was listed in the middle of the contributors, but no conventional credit was given.

In 1940 in the same way one of the first Harold Goldberg presented a complete multi-stage, DC-coupled differential amplifier [7], put back a medical application, he 1944 added a pentode (as keen current sink) [8] to advantage the bias current of say publicly first stage long-tailed pair.

Left side:
1946 G.

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

Distinction complete circuit shows but unadulterated different behaviour of the purpose level shift element which would take to much place accomplish explain here.

Previous designs esoteric used either a resistive even shift like Nyquist, or say publicly more recent glow-tube technique of  Miller (shown below), still paper a single ended input amplifier [14].
Picture above: Miller's DC-Amplifier, showing compensation of heater power variation in the first grow and differential voltage output, accommodate selectable gain by variable feedback.

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

Philbrick had been a Foxboro workman and was dealing with rank simulation of industrial processes, crystalclear described a one-tube circuit, effecting some of the fuctions oppress an Opamp.
While this order (using floating batteries for power) can’t be termed a advantageous op amp circuit, it regardless demonstrated some of the OpAmp working principles [19].

In WW2 George A.

Philbrick has archaic a member of the NDRC (National Defence Research Committee) Branch 7 [10], a unit shop the OSRD (Office of Wellregulated Research and Development) like visit other scientists, where he alien his knowledge regarding process tidiness, man machine interaction and simulation.
The NDRC Division 7 educated Antiarcraft Directors, Bomb-Sights, Torpedo Executive administratio, Guided Bombs, Aircraft-Rocket aiming chattels and simulation for development purposes.
Besides many other industrial vendors like General Electric, Westinghouse, Eastman-Kodak and much more, also leadership Foxboro Company had a transmit with the War Department [13].
When Philbrick started his repudiate business, he developed what now is known as the rule commercial OpAmp.

Below is straighten up photo of the first models produced by Philbrick. The leftist side shows the very foremost series of OpAmps, the straight side shows the better common K2-W series.

Looking back study AC-coupled amplifieres with high magnet i could find one get a feel for very high gain, combining interpretation amplifier stages with current sources:

Here another contribution, showing how ostentatious amplification could be realized indoor a single amplifier, this regarding again an AC-Amplifier, but position down to very low frequencies and having overall gain finished the low impedance points X-X of approximately 7.5 x 10⁵ per side and to nobleness high impedance points Y-Y almost 5.5 x 10⁶.

G.

Wylie, spick Scientist of  National Standards Work, Sydney, Australia described in [20] an amplifier where a paired triode, such as the little 12AX7, could be used adjoin construct a single amplifier leaf in which one triode sweep provides a high dynamic satisfy resistance for the plate compass of the other.
Such inception, when connected in cascade with respect to form an amplifier of elevated gain, provide a number disseminate advantages not realized in excellence battery-operated single stage amplifiers pointer somewhat similar principle described coarse Meissner [21] and by Schmitt [22].
Each of the greatest three stages of the amplifier represented by the figure, which is given as an illustrate, has the following properties:
(a) The dynamic resistance between righteousness points A and B psychiatry app- roximately 10 Mohms (~ R3 * mu) and lone the loading effect of say publicly input circuit of the next stage prevents the gain too closely approaching the valve addition factor, which is about Centred.

Since the valve amplification consideration is almost independent of flicker out of order conditions, particularly for high layer supply voltage and small partiality, the gain is very stable.
(b) Of a ripple power applied at A, only valuation 1% appears at B (~ ripple / mu), even realize a frequency of 1 c/s. This is of particular burden for the first stage.
(c) The current fluctuations at Spiffy tidy up, representing the signal, are give mu (=100) times less stun in a conventional amplifying depletion and the disturbance set shunt in the voltage source abutting to A is correspondingly small.
The loading effect on primacy double triode stage due get stuck the succeeding input circuit stare at be greatly reduced by on the go the following stage from decency low impedance point C (2 kOhms impedance as compared colloquium 100 kOhms at point B).

Through the reduction in representation Miller effect, the upper border of the frequency range (with small phase shift) is extensive from a few hundred come to a few thousand cycles manuscript second.
Inter-electrode capacitances still fill to the admittance to foundation from B. The gain revenue the first three stages make more complicated closely approaches the cube eliminate the valve amplification factor roost the amplifier is found jab remain quite stable.
By inflatable the very high gain write to high audio frequencies, a close up designed layout is necessary observe avoid oscillation due to rejected capacitive coupling (recommendable: first event should be built with waves microphonic triodes).

At least coming terminate to the term "OpAmp" say publicly following is showing the putsch of this term:
1947 primacy head of the wartime conference amp development work research document Prof.

Ragazzini of the University University of New York hypothetical in a key paper meaning the use of and significance mathematical relationships of OpAmps:
"As an amplifier so connected focus on perform the mathematical operations ensnare arithmetic and calculus on prestige voltages applied to its display, it is hereafter termed trivial ‘operational amplifier’."  

More evolution discharge duty followed then but the aloft described are probably the near important in the history commentary Operational Amplifiers.
More about goodness evolution of Analog Computers could be find in :
“Moving Targets“ by Simon Lavington, Impost, 2011 (British developments)
“Between Individual and Machine: Feedback, Control, countryside Computing before Cybernetics“ by Painter A.

Mindell, Johns Hopkins College Press 2004, (American developments)
“IEEE Annals of the History grapple Computing“ by IEEE, Washington (System specific documentations)

Regards
Achim

References:

[1] "Feedback Amplifiers", H. S. Black, Gong Laboratories Record, Vol. XII Pollex all thumbs butte. 10, June 1934, pp.

290-296

[2] "Regeneration Theory", Harry Nyquist, Bell System Technical Journal, Vol. 11 No.3, July 1932, pp. 126-147
[3] "Push Pull Force Coupled Amplifiers", Review of Exact Instruments, Vol. 8, January 1937, pp. 20, 21
[4] "Differential Amplifier", J. F. Toennies, Dialogue of Scientific Instruments, Vol.

9, March 1938, pp. 95-97

[5] "Cathode Phase Inversion", O. About. Schmitt, Journal of Scientific Tackle, Vol XV, London 1938, pp. 100,101
[6] "Cathode Phase Inversion", O. H. Schmitt, Review unconscious Scientific Instruments, Vol. 12 Maladroit thumbs down d. 11, November 1941, pp. 548
[7] "A High Gain DC Amplifier for Bioelectric Recording", Harold Goldberg, Transactions AIEE, Vol.

59, January 1940, pp. 60-64
[8] "Bioelectric Research Apparatus", Harold Cartoonist, Proceedings of the I.R.E., Vol 32, June 1944, pp. 330-336
[9] "A Stable Direct-Coupled Amplifier", Robert Mezger, Electronics, July 1944, pp. 106-110, 352+353

[10] Synopsis technical report of Division 7, NDRC, Volume 3, Washington D.C., 1946

[11] Service of Gun Directors M9, M9A1, M9A2, contemporary M10, FM 44-38, War Dptmt Field Manual, November 1944
[12] Service of the M9 put forward M10 Type Antiaircraft Directors, FM 44-38, Dptmt of the Drove Field Manual, August 1952
[13] Contract No.

OEMsr-1144 Supplement 3, "Development of steering mechanisms progress to torpedoes", Foxboro Company, Foxboro, Colony, Project No. 7.3-69; from Authority Document No. AD200795: Summary Mechanical Report of Division 7, NDRC, "Gunfire Control"
[14] "Sensitive DC-Amplifier with AC-Operation", Stewart E. Dramatist, Electronics, November 1941, pp.

27-31, 106-109
[15] "Unsung hero pioneered op amp" to find mark out the WWW (actually: w weak w.tayloredge.com/museum/museum/opamp.pdf)
[16] "A new Bioelectric Application - Electroencephalography", W.E. Rahm, Electronics, October 1931, pp. 11
[17] "Electrical Control of Galvanometer Characteristics", O. H. Schmitt, Newsletter of Scientific Instruments, Vol XV, London 1938, pp.

234-237
[18] "What's All This Julie Belongings, Anyhow?", published in: w exposed w.electronicdesign.com/technologies/analog/article/21763955/whats-all-this-julie-stuff-anyhow
[19] "Designing Industrial Controllers by Analog", by George Span. Philbrick, Electronics, June 1948, pp. 108-111
[20] "The use get through double triodes in high-gain low-frequency amplifiers", by G.

Wylie, Review 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 Scientific Instruments, 4, 1933, pp. 661

To say thank you the Author because you spot the post helpful or spasm done.