Hi All, If you are interested in building your own analog computer or just interested learning more about how an analog computer works, I found a PDF version of a 4 part construction article on the web. The article, I believe, is from Practical Electronics Magazine (UK) (date unknown, probably late 1970s). The amplifiers are 741 opamps. And the amplifiers even have overvoltage indicators which is a sophisticated feature usually found only on commercial computers. Part 1 is how an analog computer works Part 2 is construction details Part 3 is wiring and testing and Part 4 is programming and special circuits The file 2.25 MB Kronis, P., "Analogue Computer", Parts 1, 2, 3, 4 http://patrik.unx.nu/tech/analog_dator/anacomp.pdf --Doug ========================================= Doug Coward @ home in Poulsbo, WA Analog Computer Online Museum and History Center http://dcoward.best.vwh.net/analog =========================================