Editing Analog computer (section)

===Modern era===
[[File:Analog Computing Machine GPN-2000-000354.jpg|thumb| Analog computing machine at the [[Lewis Flight Propulsion Laboratory]] {{Circa|1949}}.|alt=|260x260px]]
[[File:Heathkit Analog Computer.jpg|thumb|Heathkit EC-1 educational analog computer|alt=|260x260px]]
The [[Dumaresq]] was a mechanical calculating device invented around 1902 by Lieutenant [[John Saumarez Dumaresq|John Dumaresq]] of the [[Royal Navy]]. It was an analog computer that related vital variables of the fire control problem to the movement of one's own ship and that of a target ship. It was often used with other devices, such as a [[Vickers range clock]] to generate range and deflection data so the gun sights of the ship could be continuously set. A number of versions of the Dumaresq were produced of increasing complexity as development proceeded.

By 1912, [[Arthur Pollen]] had developed an electrically driven mechanical analog computer for [[fire-control system]]s, based on the differential analyser. It was used by the [[Imperial Russian Navy]] in [[World War I]].<ref>{{Cite journal |last=Clymer |first=Arthur Ben |date=1993 |title=The Mechanical Analog Computers of Hannibal Ford and William Newell |journal=IEEE Annals of the History of Computing |volume=15 |issue=2 |pages=19–34 |url=http://web.mit.edu/STS.035/www/PDFs/Newell.pdf |access-date=11 February 2023|doi=10.1109/85.207741|s2cid=6500043 }}</ref>

Starting in 1929, [[Network analyzer (AC power)|AC network analyzers]] were constructed to solve calculation problems related to electrical power systems that were too large to solve with [[numerical method]]s at the time.<ref name="G12GE">Thomas Parke Hughes ''Networks of power: electrification in Western society, 1880–1930'' JHU Press, 1993 {{ISBN|0-8018-4614-5}} page 376</ref> These were essentially scale models of the electrical properties of the full-size system. Since network analyzers could handle problems too large for analytic methods or hand computation, they were also used to solve problems in nuclear physics and in the design of structures. More than 50 large network analyzers were built by the end of the 1950s.

[[World War II]] era gun [[Director (military)|directors]], [[gun data computer]]s, and [[bomb sight]]s used mechanical analog computers. In 1942 [[Helmut Hölzer]] built a fully electronic analog computer at [[Peenemünde Army Research Center]]<ref name="HsrYN">James E. Tomayko, ''Helmut Hoelzer's Fully Electronic Analog Computer''; In: ''IEEE Annals of the History of Computing'', Vol. 7, No. 3, pp. 227–240, July–Sept. 1985, {{doi|10.1109/MAHC.1985.10025}}</ref><ref name="LQl0b">{{Cite book |url=https://books.google.com/books?id=L6BfBgAAQBAJ&q=Hoelzer%201942&pg=PT138 |title=The Rocket and the Reich: Peenemunde and the Coming of the Ballistic Missile Era |last=Neufeld |first=Michael J. |year=2013 |publisher=Smithsonian Institution |isbn=9781588344663 |pages=138 |language=en}}</ref><ref name="hOc4c">{{Cite book |url=https://books.google.com/books?id=y1DpBQAAQBAJ&q=Hoelzer%201941&pg=PA38 |title=Analog Computing |last=Ulmann |first=Bernd |date=2013-07-22 |publisher=Walter de Gruyter |isbn=9783486755183 |pages=38 |language=en}}</ref> as an embedded control system (''mixing device'') to calculate [[V-2 rocket]] trajectories from the accelerations and orientations (measured by [[gyroscope]]s) and to stabilize and guide the missile.{{sfnp|Neufeld|2013|p=106}}<ref name="u9qok">{{cite journal |title=Helmut Hoelzer |first=James E. |last=Tomayko |date=1 July 1985 |journal=IEEE Annals of the History of Computing |volume = 7 |issue=3 |pages=227–240 |doi=10.1109/MAHC.1985.10025 |s2cid=15986944}}</ref> Mechanical analog computers were very important in [[Fire control system|gun fire control]] in World War II, the Korean War and well past the Vietnam War; they were made in significant numbers.

In the period 1930–1945 in the Netherlands, [[Johan van Veen]] developed an analogue computer to calculate and predict tidal currents when the geometry of the channels are changed. Around 1950, this idea was developed into the [[Deltar]], a [[hydraulic analogy]] computer supporting the closure of estuaries in the southwest of the Netherlands (the [[Delta Works]]).

The [[FERMIAC]] was an analog computer invented by physicist [[Enrico Fermi]] in 1947 to aid in his studies of neutron transport.<ref name="bwwka">Metropolis, N. [http://www.fas.org/sgp/othergov/doe/lanl/pubs/00326866.pdf "The Beginning of the Monte Carlo Method."] Los Alamos Science, No. 15, p. 125</ref> [[Project Cyclone]] was an analog computer developed by Reeves in 1950 for the analysis and design of dynamic systems.<ref name="qU5NQ">Small, J. S. "The analogue alternative: The electronic analogue computer in Britain and the USA, 1930–1975" Psychology Press, 2001, p. 90</ref> Project Typhoon was an analog computer developed by RCA in 1952. It consisted of over 4,000 electron tubes and used 100 dials and 6,000 plug-in connectors to program.<ref name="1serv">Small, J. S. "The analogue alternative: The electronic analogue computer in Britain and the USA, 1930–1975" Psychology Press, 2001, p. 93</ref> The [[MONIAC Computer]] was a hydraulic analogy of a national economy first unveiled in 1949.<ref name="iSjwP">{{Cite journal |last=Bissell |first=C. |date=2007-02-01 |title=Historical perspectives – The Moniac A Hydromechanical Analog Computer of the 1950s|journal=IEEE Control Systems Magazine |volume=27 |issue=1 |pages=69–74 |doi=10.1109/MCS.2007.284511 |s2cid=37510407 |issn=1066-033X |url=http://oro.open.ac.uk/7942/1/04064850.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://oro.open.ac.uk/7942/1/04064850.pdf |archive-date=2022-10-09 |url-status=live}}</ref>

Computer Engineering Associates was spun out of [[Caltech]] in 1950 to provide commercial services using the "Direct Analogy Electric Analog Computer" ("the largest and most impressive general-purpose analyzer facility for the solution of field problems") developed there by Gilbert D. McCann, Charles H. Wilts, and [[Bart N. Locanthi|Bart Locanthi]].<ref name="ZOi9Q">{{cite web |url=http://me100.caltech.edu/history/nastran.htm |title=History – Accounts |website=me100.caltech.edu}}</ref><ref name="jXkDw">{{cite web |url=https://books.google.com/books?id=X0UYAAAAIAAJ&q=caltech+analog-computer |title=Analog simulation: solution of field problems |first=Walter J. |last=Karplus |date=1958  |publisher=McGraw-Hill |via=Google Books}}</ref>

Educational analog computers illustrated the principles of analog calculation. The [[Heathkit]] EC-1, a $199 educational analog computer, was made by the Heath Company, US {{circa|1960}}.<ref name="HGxrP">{{cite book |last=Petersen |first=Julie K. |title=Fiber optics illustrated dictionary |publisher=CRC Press |year=2003 |page=441 |isbn= 978-0-8493-1349-3}}</ref> It was programmed using patch cords that connected nine [[operational amplifier]]s and other components.<ref name="fujYP">{{cite web |url=http://www.computerhistory.org/VirtualVisibleStorage/artifact_main.php?tax_id=01.03.05.00 |title=Heathkit EC - 1 Educational Analog Computer |publisher=Computer History Museum |access-date=9 May 2010|archive-url=https://web.archive.org/web/20100520214445/http://www.computerhistory.org/VirtualVisibleStorage/artifact_main.php?tax_id=01.03.05.00 |archive-date=2010-05-20 |url-status=dead}}</ref> [[General Electric]] also marketed an "educational" analog computer kit of a simple design in the early 1960s consisting of two transistor tone generators and three potentiometers wired such that the frequency of the oscillator was nulled when the potentiometer dials were positioned by hand to satisfy an equation. The relative resistance of the potentiometer was then equivalent to the formula of the equation being solved. Multiplication or division could be performed, depending on which dials were inputs and which was the output. Accuracy and resolution was limited and a simple slide rule was more accurate. However, the unit did demonstrate the basic principle.

Analog computer designs were published in electronics magazines. One example is the PEAC (Practical Electronics analogue computer), published in ''Practical Electronics'' in the January 1968 edition.<ref name="PE Jan 1968">[https://worldradiohistory.com/UK/Practical-Electronics/60s/Practical-Electronics-1968-01.pdf] Practical Electronics, January 1968</ref> Another more modern hybrid computer design was published in ''Everyday Practical Electronics'' in 2002.<ref name="EPE hybrid">[http://www.epemag3.com/lib/free_projects/general/1102-%20EPE%20Hybrid%20Computer%20-%20Part%201.pdf EPE Hybrid Computer - Part 1] (November 2002), [http://www.epemag3.com/lib/free_projects/general/1202-%20EPE%20Hybrid%20Computer%20-%20Part%202.pdf Part 2] (December 2002), ''Everyday Practical Electronics''</ref> An example described in the EPE hybrid computer was the flight of a [[VTOL|VTOL aircraft]] such as the [[Harrier jump jet]].<ref name="EPE hybrid" /> The altitude and speed of the aircraft were calculated by the analog part of the computer and sent to a PC via a digital microprocessor and displayed on the PC screen.

In industrial [[process control]], analog loop controllers were used to automatically regulate temperature, flow, pressure, or other process conditions. The technology of these controllers ranged from purely mechanical integrators, through vacuum-tube and solid-state devices, to emulation of analog controllers by microprocessors.