[GreenKeys] Was: TWX/TELEX now: Analog Computers

[Keith Lueck]

 The gold standard for opamps used in analog computers before the IC era was the Phillbrick K-2 series.  The great analog designer - bandgap "Czar" Robert Pease - started at Philbrick labs in the early 60's.  They used to publish the "Lightning Empiricist," which was the, "Analog Dialogue" of its' day (many reprints are available online).  I believe they were bought by Teledyne in the late 60's.
https://www.computerhistory.org/revolution/analog-computers/3/156/393

Another humorous story that appeared in that journal (I couldn't find the original), was literally chapter 1 of Jim Williams' great analog design book:
https://www.linkedin.com/pulse/barometers-analog-design-bruno-rosa

The above link cites, "The Saturday Review" - it may have been reprinted there, but I know for a fact that the original source was the Lightning Empiricist...
Have fun,
Keith
    On Thursday, April 15, 2021, 07:37:31 PM CDT, John <john at tubetestingpros.com> wrote:  
 
  

 
 
 You might be very interested in exploring "Analog Computers".  I've owned several, large and small.  They use known standardized components and voltage values to compute, and simulate, systems that vary over time.  
 
 
There is a niche for them yet today, even though the speed of even simple/cheap modern computers is now sufficient to model most things. Many industrial control system courses still have them in the labs.
 
 
However - if you have a grasp of the mathematics of what you are investigating (and it's a 'physical' system, like a weight on a spring in a viscous medium) it's trivial to "program" an analog computer to model that system, sometimes in real-time, and to make changes to system parameters (the mass of the weight for example) and have the results directly available, with no need to translate the model into some high-level language on a digital machine.
 
 
A lot of large-scale flight simulators used large analog computers to drive them.
 
Google "analog computer" to a deluge of info.
 
For a reasonably useful simulation and modeling program, see "Flowstone"
 
For the best open-source (free) modeling and simulation package out there, see "SciLab".
 

 
 
Obligatory Greenkeys:  RYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYFIGSBELLTRSCRLFCRLF
 
okay I feel better now.
 
 

 
 
Cheerz
 
John KB6SCO
 
Carson City
 
 On 4/15/2021 4:00 PM, steve bennett via GreenKeys wrote:
  
  In my first electronics class in vocational school the teacher gave us some analogy to explain a resistor. A light bulb went off in my head and I added my own analogy for capacitor and inductor. Teacher stopped me "not so fast son...you are taking it too far" 
  It wasn't until years later when I enrolled in electrical engineering I learned I was right all along and the vo-tech teacher didn't know what he was talking about. The math that describes the behavior of a capacitor is the exact same math that describes the behavior of a mechanical spring and the math that describes the behavior of an inductor is exactly the same math that describes mechanical inertia. 
  -Steve  
 
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