Microvaxen bits etc. - test-drb@ccmp.vtda.org

29 Oct 1998

-----Original Message-----
From: Tony Duell &lt;ard(a)p850ug1.demon.co.uk&gt;
To: Discussion re-collecting of classic computers
&lt;classiccmp(a)u.washington.edu&gt;
Date: Thursday, 29 October 1998 8:54
Subject: Re: Microvaxen bits etc.

...
 [Using the transceiver section of an ethernet card]

  I think it needs +-12v and +- 5v, but that's
not a big problem. (Diskless
 workstation PSU) 
Well, the card might, but the transceiver section will almost certainly
only need one supply rail. It runs off an _isolated_ (to 1.5kV I think)
PSU on the card (there'll be a DC-DC converter on the card for this).
I've never seen such a converter than needs more than one supply voltage
input. 
Yep.  Dead right.  12-15v dc to feed a dc-dc xvtr that produces 9v to run
the NE8392C xcvr chip.

...
    Did I mention that you'll need the data sheets on
the transceiver chip? 
 You did.  Know a source?  Online one preferably? 
Sure. Try the semiconductor manufacturers. AMD, National Semiconductor,
Philips, possibly. They should have the data sheets in pdf format to
download. I remember downloading the National Semiconductor
8390+8391+8392 data sheets about a year ago. 
Exactly as you recalled.  I have the PDF files with data for the lot.
Amongst other things, there is a page with a "Typical Application" which is
a cct diagram of a what amounts to an AUI-Thin cable transceiver.  Complete
with pinouts of a typical pulse xfmr.  Exactly what I needed.
So I'm gonna build me a couple or three from bits of network cards. Should
be able to do it on
a piece of veroboard in about an hour or so.  Cabling can be avoided by
connecting the pins of
a male 15pin d directly to the veroboard, then the whole thing can plug in
to the ethernet AUI port on
the back of the VAX.
This has basically solved my problem, as I have several elcheapo ethernet
cards laying about
that can supply all the parts except the 15 pin male d.

Thanks for your help.

Cheers

Geoff
Computer Room Internet Cafe
Port Pirie
South Australia.
netcafe(a)pirie.mtx.net.au