Hi list,
It happens that I may have been one of the people to buy from the lot of AppleNet cards that Al Kossow advertised on the list a while back. I promised him that I would try to derive a schematic of the card by early next year, but it turns out that I couldn't wait. I got to work right away.
Now I have to warn everyone that I'm not an EE, and so even though I can use a multimeter, there's a lot I don't know about how circuits are arranged or how to draw up a good schematic using all of the usual conventions that EEs use. It's likely that what I've come up with has plenty of bugs. And---ordinarily I'd wait until I had time to study and understand the circuit, since that's a good way to spot mistakes, too.
But: the festive season is coming, and my work table needs to move to make room for the Christmas tree. December is always busy anyway, so it's probably better to release what I have now, then hopefully return to the project in 2019 sometime.
So: please feel free to take a look at my early draft! You can find the schematic on my github:
(for a PDF, select "applenet.pdf" and then click the Download button for a closer look.)
Now a couple of the labels are intentionally silly, but there's probably plenty of things there that are unintentionally funny, too. If you are more of an electronics pro than I am, I'd be very happy if you could have a look at the schematic and see if anything looks obviously wrong to you. It'll still be a few days before the work table needs to go away, so I can reexamine the parts of the circuit that you're wondering about and hopefully make a correction. Any other suggestions are welcome, too.
OK, that's all. I hope this is interesting,
--Tom