analog computers

The MARCH collection of analog computers
The EAI TR-20 analog computer was popular in engineering schools from the 50s to the 80s
for teaching control theory.
Electronic Associates Incorporated was a local mfgr
at 185 Monmouth Parkway / West Long Branch, New Jersey 07764
To learn more, see EAI TR-20 analog computer donated by Nick Lordi.
Heathkit EC-1 Educational Analog Computer
Display case, from back to front:
  • Jeppesen E6B-1A Flight Computer
    (circular slide rule)
  • slide rule and "how to use it" book
  • the tube modules are George A Philbrick Research GAP/R K2-W, K2-P
    the first commercial OpAmps (Operational Amplifier) in 1952.
  • The lucite block with the sandglass is a 3-transistor card from Mobidic
  • The card with the pins is a 3-transistor card from the Univac 1219B
Tube OpAmps, Slide rules & manual donated by Jeffrey Jonas
To learn more, see
"Computor" tubes I salvaged from a motor/servo/synchro test set.
According to the George A. Philbrick Researches Archive,
the company launched the commercial use of the Operational Amplifier in 1952: the GAP/R model K2-W.
My photos are now on this page too.

The Op Amp applications handbook By Walter G. Jung shows the GAP/R K2-W op-amp and mentions the K2-P chopper-stabilizer.

This PowerPoint document cites wikipedia: In 1953, vacuum tube op-amps became commercially available with the release of the model K2-W from George A. Philbrick Researches (GAP/R). Two nine-pin 12AX7 vacuum tubes were mounted in an octal package. The model K2-P chopper used the non-inverting input. This op-amp was based on a descendant of Loebe Julie's 1947 design and, along with its successors, started the widespread use of op-amps in industry.
The IEEE Control Systems Magazine (vol. 25, no. 3, June 2005)
featuring "History of Analog Computing"
by VCF east 2012 speaker Kent H. Lundberg, Ph.D (his CV)
General Electric manufactured both analog & digital computers.
The sales kit for the GE 225 computer included a slide rule and abacus to teach analog vs. digital computers.

Slide rules are analog calculating devices.

Citing wikipedia for analog computer
An analog computer is a form of computer that uses the continuously-changeable aspects of physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved. In contrast, digital computers represent varying quantities incrementally, as their numerical values change. Mechanical analog computers were very important in gun fire control in World War II and the Korean War; they were made in significant numbers. In particular, development of transistors made electronic analog computers practical, and before digital computers had developed sufficiently, they were commonly used in science and industry. Analog computers can have a very wide range of complexity. Slide rules and nomographs are the simplest, while naval gunfire control computers and large hybrid digital/analog computers were among the most complicated.
The Norden bombsight is one of the most famous analog computers from WW II.
Before his leadership in digital computing, Vannevar_Bush built a differential analyser
The differential analyser is a mechanical analogue computer designed to solve differential equations by integration, using wheel-and-disc mechanisms to perform the integration.

The first widely practical differential analyser was constructed by Harold Locke Hazen and Vannevar Bush at MIT, 1928-1931, comprising six mechanical integrators.

Bob Pease was one of the most famous analog electrical engineers
particularly for his Analog Seminars, "Pease Porridge" column and the "Analog By Design Show" webcast.
He worked for National Semiconductor (now TI: Texas Instruments).

citing wikipedia
Robert Allen Pease (August 22, 1940 - June 18, 2011) was an analog integrated circuit design expert and technical author. He designed several very successful "best-seller" integrated circuits, many of them in continuous production for multiple decades. These include the LM331 voltage to frequency converter, and the LM337 adjustable voltage regulator.

He started work in the early 1960s at George A. Philbrick Researches (GAP-R).
GAP-R pioneered the first reasonable-cost, mass-produced operational amplifier ("op-amp"): the K2-W.
At GAP-R, Pease developed many high-performance op-amps, built with discrete solid-state components.
remembering Bob Pease
Legendary Analog Expert

Texas Instruments honors the accomplishments of the company's legendary design engineer, Bob Pease, who died on June 18, 2011. During his 33-year career at National Semiconductor, Bob received 21 patents and designed more than 20 integrated circuits. Bob Pease was loved by the analog community and we celebrate Bob's passion for analog.

He was listed as one of the top 10 analog engineers of all time in a 2009 EE Times story.

YouTube video of a totally mechanical Navy fire control computer
Mechanical Computer - Basic Mechanisms In Fire Control Computers
A 1953 training film for a mechanical fire control computer aboard Navy Ships. Amazing how problems of mathematical computation were solved so elegantly in "permanent" mechanical form, before microprocessors became inexpensive and commonplace.
I wish I had a photo of a table lamp from army engineer John Bialo.
It looked like a piece of modern art: sleek curvey wavey glistening steel.
In actuality it was a "barrel cam", the surface expressing equations for the artillery delay.