Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!elroy.jpl.nasa.gov!ncar!ames!vsi1!teda!ardai
From: ardai@teda.UUCP (Mike Ardai)
Newsgroups: sci.electronics
Subject: Re: question: power supply for expansion chassis
Message-ID: <18252@teda.UUCP>
Date: 18 Dec 90 16:59:01 GMT
References: <1990Dec17.004840.22780@csn.org>
Distribution: usa
Organization: Teradyne EDA, Inc.
Lines: 19

In article <1990Dec17.004840.22780@csn.org> grusin@tramp.Colorado.EDU (GRUSIN MICHAEL) writes:

[ Building an expansion chassis for an Amiga and wants to know how to hook
  up the new supply]

Just hook up the grounds in common between the 2 supplies, and leave the 
other voltages separate.  You should never hook supplies in parallel unless
they were designed to be, since if their voltages are not *identical*, one
will try to drive the other.  You might want to use a relay (watch the 
contact current ratings), driven by the Amiga's old 5V supply to cut out
the new supply's outputs in case the Amiga could be powered off while the
expansion chassis is on.  Most ICs don't like having their pins driven
without Vcc.
/mike

-- 
\|/  Michael L. Ardai   Teradyne EDA East
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