Date:    Wed, 12 Sep 2012 14:26:08 +0000
From:    Peter Takacs
To:      Biduleohm
Cc:      Skyler Hagen
Subject: 1960 schematic


Hello Franck

Here is another schematic for the game that was drawn in 1960 after the 2nd version of the game was built. One of our summer students, Skyler Hagen,  found it in our archives last year. It is not mentioned in any of the Higinbotham documents, so we did not know it existed. In any case, it is laid out in a different manner than the earlier schematic, which makes it difficult to compare directly. The important thing to see is that they added more diodes to the outputs of the op amp stages to make sure the relays only were on during one polarity of the output. This allows for better control of the position sensing of the ball relative to the end of court and the height of the court and net.

I haven't checked this schematic very thoroughly, so use it at your own risk.

Good luck,
Peter Takacs


Attached files: http://biduleohm.free.fr/fichiers/tennis_for_two/1960_schematic.pdf


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Date:    Wed, 12 Sep 2012 23:26:44 +0200
From:    Biduleohm
To:      Peter Takacs
Cc:      Skyler Hagen
Subject: Re: 1960 schematic


Hello,

Thanks for this new schematic. I love so much that kind of thing, when you found a true and unique piece of history like this :D

In fact there is maybe an indirect mention in the Higinbotham's notes, page 3, second paragraph. He says that in 1959 a second version of the game with a bigger tube and a selectionnable gravity has been made. The thing that makes me think that is the "stepping switch" which maybe can be used to change the gravity.

It seems very similar to the first schematic. I think I will use the first schematic and pick some details of this schematic.

And now I know why the op-amps 5 and 10 and the relays 7 and 5 need to be separated: there is a diode on Ry 7 but not on Ry 5.

I also have a question about the recent version you have simulated with actual op-amps: why you have replaced some resistors of 1M by some of 100K? It's because the op-amps have a low input impedance? or for an other reason?

Thank you again.


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