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From: "Ken Taylor"
Subject: Re: [Newbie]: Testing a +5V IC regulator
Date: Wed, 13 Nov 2002 16:04:39 +1300
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Is the 78L05 oriented correctly? Or is there a reverse voltage protection
diode across it (which may be incorrectly inserted?). Measure across the
78L05 - it may be blown or you may have a short circuit.
"Jeff Stout" wrote in message
> You may have also fried your TTL/CMOS chips too.
> You didn't say, but what kind of IC's are your using?
> Jeff Stout
> Alistair Campbell wrote in message
> > I am new to electronics so this is probably a silly question.
> > I am building a kit parallel port interface. The power supply to the
> > various IC's is via a 78L05 IC which produces 5v from 9v.
> > When I test voltage to the supply pins on the IC's they rate at 9v
> > when they should rate at 5v (+/-0.5v).
> > Tracking this down I get 9v at the output pin for the 5v regualtor. I
> > am using a multimeter and checking by connecting one probe to the
> > output pin and one probe to the negative rail.
> > Does this mean that the IC 5v regulator has failed? Or am I doing my
> > testing wrong?
> > Any thoughts would be much appreciated.
> > Alistair Campbell
> > Brisbane, Australia
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