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Thread: I tried putting this in the electronics section but got no response, maybe here?

  1. #1 I tried putting this in the electronics section but got no response, maybe here? 
    Forum Ph.D.
    Join Date
    Jul 2011
    November 4th, 2011, 10:59 PM
    In grad school, 40 years ago, I worked with a fasinating device but do not remember its name or who invented it. I hope someone will recognize the discription and help me with its name and inventor.

    The device is brief case sized. Indeed was in built into a brief case. It consisted of a rectifier(?), that is a electical device that converted house current to direct current, and allowed the user to output direct current in precisley measured amounts, ie micro amps. The output was through plug in leads with alligator clips on them. The leads were just long enough to reach the the space inside the brief case.

    There were also leads with needle probs on them that could be used to measure charge in similar micro amounts.

    The electronics took up about one quarter of the space inside the brief case. The remainder was a sheet of cork board. A stack of carbon paper sheets, and some metal push pins.

    In use one attached a sheet of carbon paper to the cork board, and drew a map of the physical territory under investigation with number 2 pencil lines representing roads and cuts with a razor knife representing rivers or other barriers to passage. The carbon paper has a uniform electical resistence but does conduct electricity, the additional carbon in the form of graphite from the pencils provides local paths of lower resistence. One then input charge in amounts proportional to the population of the towns or neighborhoods under investigation.

    With the probe you then read the charge passing to other points on the map. As a class we collected raw population data and demonstrated that the device did infact allow accurate prediction of human activity. You could predict how many people from one town would shop in another, or use the medical clinic there. It predicted the use of "central place functions".

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  3. #2  
    Brassica oleracea Strange's Avatar
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    Oct 2011
    Sounds like some sort of analog computer measuring areas, effectively doing integration of the curves you trace.

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