https://video.joostrekveld.net/videos/watch/5823be39-5a36-4cf6-8bdc-58c97bf9685b First experiments from 2021 with automatically tracing the electrical fields in resistive paper with copper electrodes. The left machine traces the field: the Comdyna analog computer at the back drives the X-axis and adjusts the Y-axis so that the probe follows an equipotential line. The right machine copies the movement because it is driven with the same XY voltages and draws the lines on paper. This use of resistive paper to model all kinds of field equations was invented in the 1920s and was very common until well into the 1960s and 1970s. Just after the second world war it was used extensively for modelling air flows around supersonic planes and rockets. Later it was used to model electron trajectories in tubes, accelerators and in the first integrated circuits. In the Netherlands it was used for modelling water flows through dikes. It is an almost forgotten technique that is very elegant and simple: it can be done by hand with hardly any tools and it can be used without understanding any of the math involved. It is a directly analog and truly two-dimensional way to compute. Thu, 03 Sep 2026 03:04:51 GMT https://validator.w3.org/feed/docs/rss2.html PeerTube - https://video.joostrekveld.net https://video.joostrekveld.net/lazy-static/avatars/e35ea6d1-b888-421d-b49f-14ee9051e5ed.jpg https://video.joostrekveld.net/videos/watch/5823be39-5a36-4cf6-8bdc-58c97bf9685b All rights reserved, unless otherwise specified in the terms specified at https://video.joostrekveld.net/about and potential licenses granted by each content's rightholder.