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From: myers@hpfcdj.HP.COM (Bob Myers)
Newsgroups: sci.electronics
Subject: Re: Power Supply question
Message-ID: <17660155@hpfcdj.HP.COM>
Date: 1 Mar 91 19:05:24 GMT
References: <22940@hydra.gatech.EDU>
Organization: Hewlett Packard -- Fort Collins, CO
Lines: 24


>by using regulators.  Here's the question:  Can regulators be
>wired in parallel to increase current handling if identical
>regulators are used?

A much better way to acheive higher current capacity is to use a single
regulator to set the base voltage for a pass transistor which can handle the
required current.  See my previous posting on the Zener-diode-based regulator
for a brief description of how a pass transistor is used; the regulator 
IC basically takes the place of the Zener, and so must be set up so that
its output voltage is greater than the desired output by the BE drop (about
0.6 to 0.7V; twice this if you're using a Darlington configuration for the
pass transistor).  Therfore, you'll want an adjustable, instead of a "fixed,"
regulator.  (And note that now you can use a regulator with a much lower
current rating!)

A good source of information on application of regulator ICs - this included -
is National's _Voltage_Regulator_Handbook_.  Try the library of the local
engineering school.


Bob Myers  KC0EW   HP Graphics Tech. Div.|  Opinions expressed here are not
                   Ft. Collins, Colorado |  those of my employer or any other
myers@fc.hp.com                          |  sentient life-form on this planet.