Electronics > Projects, Designs, and Technical Stuff

Home Brew Analog Computer System

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GK:
Just soldered the very last connection inside the display unit. I still have some lengths of 10x10mm square aluminum rod to cut, drill and tap to attach the top/lid before I can call this complete and bolt it into position in the 19" rack, but it's currently over 50 deg. C in the garage so I think I'll put off doing that for another day.

A graticule for the display will be electronically generated by a separate patch-able  unit, which will mount in the rack immediately below the display unit. This is what I am currently working on. The drawing of the graticule on the screen will work on a time-shared/alternate basis, synchronized/multiplexed by the computers control unit (the graticule being scribed in the computers repetitive mode whilst the integrators are being reset to initial conditions).

With the CRT having been idly sitting around lots operating equipment for some time in the meanwhile, it looks like the shadow mask has become non-uniformly magnetized a far bit. If several more power on/off cycles of the internal degausing circuit does not fix the colour impurity (it's a long time to wait for the PTC thermistor in series with the degausing coil to cool down again) I might have to home-brew a heavy-duty wand.











GK:
Just for fun this evening I worked out a breadboard implementation of the "bouncing ball in a box" analog computer simulation detailed here: http://www.analogmuseum.org/english/examples/bouncing_ball/

It was a success:
 
EDIT: video deleted

The solution runs for ~20 seconds before automatically resetting/restarting. If you turn the volume right up you can hear the DPDT relays clicking. A more refined version would use solid-state analogue switches rather than relays, but I used what I had at hand. Here is my schematic:

EDIT: schematic deleted

EDIT:
Oops. I knocked this thing up on the breadboard in a bit of a rush "on the fly" and have just noticed that I got some signs mixed up in the circuit for solving x and the result is that (in the horizontal motion) rather than loosing speed with time the ball (defying the laws of physics!) gains speed instead. It's 1am now and I am going to bed. Will fix this tomorrow and up-load a replacement video and schematic.

BrianHG:
I thought it was meant to do that.  It looked cool...

GK:

--- Quote from: BrianHG on January 11, 2017, 03:01:59 pm ---I thought it was meant to do that.  It looked cool...

--- End quote ---


It did look cool, but unfortunately no, the ball gained energy with time. Anyhow, I fixed it and now it operates properly. IMO it looks even cooler now that the ball movement conforms to reality, slowing down with time and eventually almost coming to a halt. Here is a new video and the revised schematic:



 

BrianHG:
Your right, that one's cooler...
Now all you need is 3 push button paddles, one for each border, to manually add energy back into the bounce only when struck exactly at the right time changing this into some sort of user game, or pushing just prior to the ball hitting it's border stealing it's energy slowing it down further.

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