>From: "Patrick Finnegan" <pat_at_purdueriots.com>
>
>On Sat, 2 Nov 2002, Patrick Finnegan wrote:
>
>> I managed to pick up a COMDYNA GP-6 analog computer a couple days ago out
>> at University Salvage. I initially bought it for its nixie tubes, not
>> knowing what it was, and then was a bit dissatisfied with the fact that
>> they were not in great shape.
>>
>> After taking a few seconds to look at it and try to determine what is was
>> with all the banana jacks on the front, I thought "Hmm, it adds and
>> multiplies... google says 'Analog computer'... Wahooo!!"
>
>More info about the one I have - looks to be an early model - with nixie
>tubes intead of the modern LED voltmeter. Also, the problem with the
>display tubes went away when I reseated the display cards in their
>sockets.
>
>After playing with this little guy, I'm suprised at how stable the
>components are - when I'm not touching anything, there's basicall NO
>jitter on the display. It looks like some component values have
>deteoriated or drifted a bit, but seems in nearly excellent shape. I'm
>about to go out to RatShack so I can get some more banana plugs and
>create some more patch cables (assuming that they still sell those...)
Hi
The absolute voltages read are not an issue because you are looking
for relative changes. Still, the resistors and capacitors on the
patch field need to have tight tolerences to get accurate results.
>
>One last thing - does anyone have an idea of what the "SW" and "OP" jacks
>at the bottom of the front panel are, and how to use the multipliers? I
>can't quite seem to get them to 'multiply'...
The multipliers may be over ranging. These usually only work over
a small range of inputs. It might also be that your unit doesn't
include the multipliers. Most analog computing functions don't
require the nonlinear operation of multipliers and use mostly
integrators and adders.
Did you look at the page:
http://www.comdyna.com/gp6panb.htm#MULT ??
It describes the use of the multiplier. It needs to be used in
conjunction with an amplifier and feedback resistor.
You might look at the bouncing ball routines for the EC-1.
It looks like you should have 8 amplifiers. I think this is
enough to do this routine with. I'm not sure if the info for
this is on a web page someplace.
Dwight
>
>Thanks for any info
>
>Pat
>--
>Purdue Universtiy ITAP/RCS
>Information Technology at Purdue
>Research Computing and Storage
>http://www-rcd.cc.purdue.edu
>
>http://dilbert.com/comics/dilbert/archive/images/dilbert2040637020924.gif
>
>
>
>
Received on Mon Nov 04 2002 - 13:05:00 GMT
