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hexsane
September 23rd, 2009, 02:36 AM
These have been sitting in a bin in Omaha for a while. I thought they were some early type of electronics trainer. I found out in another thread here what they actually were. Although having the computers is pretty cool finding the maintenance manual sitting under them was even better. These things are heavy! If you have ever picked up a standard table top 9-track drive (not the slim model) the weight and size is roughly equal. Now I need to get some help to get them out of the trunk of the car and into the house.

http://linkdirectory.tv/pics/tr20s.jpg
http://linkdirectory.tv/pics/tr20-1.jpg
http://linkdirectory.tv/pics/tr20-2.jpg
http://linkdirectory.tv/pics/tr20stuff.jpg
http://linkdirectory.tv/pics/tr20maintman.jpg

nige the hippy
September 23rd, 2009, 04:55 AM
I have an EAI user manual for the 1000 (later machine) I can email you a copy if you like. I got it online, but can't remember where. there's a lovely analogue computing web-museum at "vaxman's" site http://analogmuseum.dyndns.org/english/

That may be where I got the manual.
I wish I'd picked up the analogue plotter when I got my machine. There is also a multi-channel vector scope made by eai that would be great to watch output on. I guess I'll just have to use my scope.

Dwight Elvey
September 23rd, 2009, 07:21 AM
Wow, these are really cool. It looks like you even got a spare
program board. You got a few patch cords but you'll find you
never have enough of these. Pomona make nice ones but the prices
will make you gag.
The idea is that you can create most any simulation that can
be written as a differential equation and the occational non-linear
function. The trick is to convert the differential equation into a
intergral equation ( get out you old calculous book ). Once that
is done, you can then create the simualtion.
A greate example is the bouncing ball as in the Heathkit EC-1
manual. There are a few web pages as well. Always look for the
specific computers names as well as generic "analog computer".
Dwight

barythrin
September 23rd, 2009, 09:17 AM
lol wow. REAL computers. You going to try and get them up and running? Sounds like an unbeatable project. http://archive.computerhistory.org/resources/text/EAI/EAI.TR20TR48.1964.102646218.pdf for some awesome pics.

Did this single-handedly allow you to update your status on the computers older than you thread?

Chuck(G)
September 23rd, 2009, 09:23 AM
These would be from the 1970's, no? I seem to recall that EAI was still pumping these out (as well as a few hybrid models) then. So, depending on one's age, this may not qualify for a "system older than you".

barythrin
September 23rd, 2009, 09:28 AM
Right, some of you there's no hope lol (j/k!!) I was originally trying to find the date before I posted but easily was distracted by who knows what. The quick thing I read just said "60's" hence my comment. Per this site http://userwww.sfsu.edu/~hl/c.EAI.html looks like 1964. Pretty good age, and analog computing is such an awesome concept. That's funny that it really and rightfully dwarf the Altair, etc in age and significance. I imagine it may be more difficult to appease the better halves out there though with the lack of blinken lights.

Also, Dwight I remember you posting that to another person here (was it Bill or Evan maybe?) that I think came across one of these and started to try and get it running.

VintageComputerman
September 23rd, 2009, 09:46 AM
These have been sitting in a bin in Omaha for a while.

It's like found money!!!

I bet you could get at least a grand each for those.

dave_m
September 23rd, 2009, 11:47 AM
Nice gadgets. I remember taking a class that required lab sessions with the analog computer. It was a lot of fun patching the program in and setting the veinier pots. What a thrill to see the answer come out on the plotter and to change a parameter and see the immediate response.

It's been so long, I have some questions. Where are the Op Amps? I seem to remember Op Amp symbols on the board. How are the initial conditions set up? And how did one start the simulation?

Chuck(G)
September 23rd, 2009, 12:30 PM
The op amps are along the top of the machine, were you see the row of knobs. There's a manual here. (http://analogmuseum.dyndns.org/library/tr20_op_ref.pdf)

pontus
September 23rd, 2009, 02:31 PM
I have two EAI-180 at home. I think they date to 1968.

EvanK
September 23rd, 2009, 04:25 PM
We have a good-condition TR-20 in our museum here in New Jersey, with a thorough complement of manuals and patchboards. It is VERY heavy!

Here is a BIG picture .... zoom in and you can see every atom. :)

http://snarc.net/tr20.jpg

VintageComputerman
September 23rd, 2009, 05:27 PM
Anyone happen to see this on ebay? Vintage 1974 Scelbi-8H MicroComputer with Manual $12,100.00

Dwight Elvey
September 24th, 2009, 06:19 AM
Anyone happen to see this on ebay? Vintage 1974 Scelbi-8H MicroComputer with Manual $12,100.00

?????????????????????????????????
Dwight

Dwight Elvey
September 24th, 2009, 06:36 AM
Right, some of you there's no hope lol (j/k!!) I was originally trying to find the date before I posted but easily was distracted by who knows what. The quick thing I read just said "60's" hence my comment. Per this site http://userwww.sfsu.edu/~hl/c.EAI.html looks like 1964. Pretty good age, and analog computing is such an awesome concept. That's funny that it really and rightfully dwarf the Altair, etc in age and significance. I imagine it may be more difficult to appease the better halves out there though with the lack of blinken lights.

Also, Dwight I remember you posting that to another person here (was it Bill or Evan maybe?) that I think came across one of these and started to try and get it running.

Hi
Bill has a small SystronDonner. It is an analog computer but not the
same as a EAI with 20 amps. I have a Comdyna 20 but there are a number
of features, especially the non-linear functions, that it doesn't have.
I also have a Hearhkit EC-1. It has 9 amps but no non-linear functions.
You have to add you own diode to be the ground surface in the bouncing
ball program.
The Comdynas were mostly sold to schools while the EAIs were mostly
used for industrial purposes.
Many games can be programmed on analog computers. Things like
lunar lander and pong come to mind.
Dwight

saundby
October 16th, 2009, 03:27 AM
I used to use a bunch of EAI computers at work, controlling valves on rockets during ground testing. My favorite was a later model that used a digital computer as a sort of programmable patchboard. You never had to go looking for the bent leaf on that one!

The small ones are great fun, too. Looks like quite a find.

Now you need a few boxes of patch cords.

Dwight Elvey
October 20th, 2009, 08:03 AM
Hi
Wondered if you've had a chance to play with your TR-20s yet?
I was just looking at ebay and there is an EC-1 that is already
at $700 with no knobs and no component patch parts?? It
isn't even tested to work.
Dwight

hexsane
October 20th, 2009, 11:51 PM
I have moved them into the house but that is all I've had time for at this point.

-Matt

servoguy
January 21st, 2010, 09:50 PM
Hi, Everyone. I just joined this forum. I worked for EAI back in the '60s, and used their analog computers until 1983. I am a friend of Bernd Ulmann (vaxman) who has a personal analog computer museum at www.vaxman.de. He is trying to save all the analog computers, and recently acquired an EAI Pacer 700 which is a large scale 100 volt machine. This may be the only 100 volt solid state machine that has survived.

I would like to acquire an analog computer if any of you know where there is one that is available.

B

pontus
January 21st, 2010, 11:57 PM
Vaxman (Bernd Ulmann) is nice guy, he helped me out with manuals for my EAI machines.

Dwight Elvey
January 22nd, 2010, 04:23 PM
Hi
I've not got any for sale but expect to have some fun
with mine once I get my Nicolet DSO working. My analog
computer and the DSO should make a perfect combination.
I see these come up often on eBay. Many less than $60.
Analog computers go for much higher prices lately.
Dwight

Dwight Elvey
January 24th, 2010, 06:48 AM
Hi
I got The Nicolet 2090 scope working this weekend. Finally
got some free time to install parts ( Tantalum Cap, power resistor,
power transistor and regulator ). I had to do a little fiddling.
The original regulator was a LES723 which I'd thought
was identical to a LM723. It turns out the LES723 uses a
2.5v reference instead of a 7v.
I changed the feedback resistor and all is now fine.
The scope works great. Now to dig out my analog
computer and start making things happen.
Dwight