OT? Ethernet transceiver

Get a chip eg RTL8019AS, throw in a few passives, led an a line transformer(I like the Halo components) and Bob's your Auntie, you have a working interface.

What most hobbyists do(inlcuding myself) is to interface with a standard network card. Old isa NE2000 compatible cards are as cheap as chips and are easy to interface. For a less messy solution(read smaller) is to buy one of the many interface boards available for sale e.g. at

Cheers, Jon

Thanks for your replies.

Actually I should have been more clearer. I'd like to implement the PHY layer of an Ethernet transceiver. So for instance, Intel has some good documentation on their transceivers. However they only describe the circuitry required. I'd like to learn those circuits and build my own (using cheap TTL parts for instance). Just a as-simple-as-possible circuit(s) so that I can truly understand the PHY layer of 802.3.

Thanks again, Dennis.

Aha. You're struggling with the same problem I did. The electrical specs are pretty difficult to get, probably due to the fact that IEEE is selling the whole standard (1600 pages, IIRC).

I was not building the low-level interface, but debugging one (a SMSC 91C94).

A kind of clue is available in the data sheets and app notes of the SMSC 91C111 Ethernet chip (it's a 10/100 Mbits/s thing). The signal waveforms and the fact that the line impedance is around 120 ohms will quite well tie the design.

HTH

Thanks for the reference! I'll check it out. Dennis.