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On 2018-03-02 12:25 AM, Ronald Carlson wrote:

Anyone have a Tek 503 that's looking for a new home?

The 503's specs fit nicely as an output display for an analog computer project I'm working on.

I'm curious about your analog computer. Are you
documenting/blogging/video'ing this anywhere? What is the goal?

I'm also working on circuits to drive X-Y displays, but at a very basic
level since I'm an electronics beginner.


--Toby

Or, perhaps there's a better, newer model the group could recommend?

The identical low frequency response horiz and vert amplifiers with a
square display make it initially an interesting option.

TIA, Ron

Toby,

Documentation is just a notebook, a few pics before disassembling anything important.
Analog computers are two Comdyna GP-6. FWIW, the system could modeled in MatLab, Mathematica, or even MathCad. This project is modeling some audio transfer functions - it will be quicker for me to optimize by seeing and hearing the residual errors. For the display a vintage Tektronix 503 will do; has identical X and Y amplifiers so additional scaling circuitry and their effects is eliminated.
Also checking out Rolynn's suggestion of a 602 or 604 monitor.

Thanks, Ron

Thanks for the extra info. I certainly wish I could peer over your shoulder, I'd probably learn a lot.

A very cheap X-Y option right now is a 1720 vectorscope, if that has the bandwidth you need; it's one of the devices I'm using to test my circuit with. They are small, lightweight, and currently cheap on ebay (there's a $10 one right now). The 60x family seem to be very hard to find these days (although a friend bought a 603 from Sphere recently, which I am about to try out).

--Toby

I'd recommend just using almost any analog scope that has X-Y capability for display. For low frequencies including audio, the response of the V and H should be virtually identical - you can easily check to be sure. Scaling is no big deal, and can be set up with the scope's range, variable, and position controls to whatever is needed. Even if not, a simple interface circuit should do the trick. You can also use a DSO if it has X-Y, to record very slow or single-shot experiments. Or, an analog storage scope.

I've always had a soft spot for analog computers. Years ago, I had planned to build one, with lots of the usual function elements, and also some digital (kind of cheating) enhancements like A/D-EPROM-D/A operators for non-linear and arbitrary functions. The problem was that there were so many possible options that my tendency to overdo things would have made it a mind-boggling, complicated mess of functions and interconnect issues. So I never did it, but it's fun to think about.

Until this discussion came up, I had no idea that analog computers are still so popular in some circles - looking online a little now, I see that they are alive and well to some extent, even though PCs and SW can do all that and more. There's something to be said for the real thing, hands-on experience.

BTW, I stumbled upon a manual for the GP-6, that appears to include all the circuit schematics. If you haven't found this already, here it is:


Good luck,
Ed

On 2018-03-02 3:31 PM, Ed Breya via Groups.Io wrote:

I'd recommend just using almost any analog scope that has X-Y capability for display. For low frequencies including audio, the response of the V and H should be virtually identical - you can easily check to be sure. Scaling is no big deal, and can be set up with the scope's range, variable, and position controls to whatever is needed. Even if not, a simple interface circuit should do the trick. You can also use a DSO if it has X-Y, to record very slow or single-shot experiments. Or, an analog storage scope.

I've found X-Y mode on a digital scope (TDS460A at least) to be
extremely unsatisfying. It seems to be far from the sweet spot of what
DSO's can do.

I've always had a soft spot for analog computers. Years ago, I had planned to build one, with lots of the usual function elements, and also some digital (kind of cheating) enhancements like A/D-EPROM-D/A operators for non-linear and arbitrary functions. The problem was that there were so many possible options that my tendency to overdo things would have made it a mind-boggling, complicated mess of functions and interconnect issues. So I never did it, but it's fun to think about.

When I think about such a project I think that a useful role for digital
would be in the (re)configuration of a module fabric (e.g., analog
crossbar switches).

There is also this:

But this is probably off topic by now...

--Toby

Until this discussion came up, I had no idea that analog computers are still so popular in some circles - looking online a little now, I see that they are alive and well to some extent, even though PCs and SW can do all that and more. There's something to be said for the real thing, hands-on experience.

BTW, I stumbled upon a manual for the GP-6, that appears to include all the circuit schematics. If you haven't found this already, here it is:


Good luck,
Ed

Or find a Tektronix 536 oscilloscope and put identical plug-ins in the vertical and horizontal channels. Get a T plug-in with it so you have a time base if needed.

Byron WA6ATN

From: Ronald Carlson <ronald.carlson.54@...>
To: [email protected]
Sent: Friday, March 2, 2018 10:29 AM
Subject: Re: Analog computing, X-Y display, was Re: [TekScopes] Wanted: Tek 503

Toby,


Also checking out Rolynn's suggestion of a 602 or 604 monitor.

Thanks, Ron



I've got a 608 monitor that works well..It was a piece of medical gear ..Dumped the med stuff and built the 'w7zoi Specan' into the vacant space...Has x,y,z outputs also for my eventual curve tracer
Jim