On 5/8/2006 at 11:18 AM Tim Shoppa wrote: My recollection of the EC-1 was that a scope was considered necessary by Heath to use the thing. IIRC, the op-amps in it were okay, but weren't precision affairs, like the stuff from Philbrick. Potentiometers were plain old carbon units, not precision 10-turn units. Think of it as more of a "trainer" than a quality analog computer. I think the only interesting problem that I ever got going was the bouncing ball. There were many other "trainers". I recall one for digital computers that was essentially a large metal drum with lights and switches serving as memory. One would take large (laminated?) cards perhaps 10" wide and wrap them around the drum, then, as the drum rotated, the lights would instruct you what to do. Exactly the same timeframe as the EC-1. At about the same time as the introduction of the EC-1, Argonne National Labs was trumpeting their hybrid computer. (Now THAT would be a collector's item!) :) It was hard back then to think of the EC-1 as a "computer" since it wasn't a stored-program unit. "Computers" of this sort have been around for a long time--in the industrial process control area, the work was often done with pneumatics or hydraulics--there were sqare-root extractors, differentiators, etc. And what is your gas or water meter other than an integrator? Long before the use of electronics for computation, rather sophisticated mechanical analog computers were being used for military fire control applications. If I acquire a ball-and-disk planimeter, is it a vintage computer? Cheers, Chuck

Ya, I'd like to see him solve the state of three loosely coupled oscillators with his calculator. One can do this with the EC-1. The lack of a multiplier is a tough one for more complicated operations. Still some non-linear things ca be done with a diode, as is done in the bouncing ball. Dwight