But did it work again afterwards????
Richard

> -----Original Message-----
> From: David Covick [mailto:dac@WEST.NET]
> Sent: Tuesday, June 01, 1999 1:55 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: Reverse Polarity Protection for 3V PIC Circuit.
>
>
> Tony,
>
> I just finished a project that uses 4 AA batteries.  At over
> 6 volts, I
> applied the voltage backwards for maybe 2 minutes or more.  I
> wondered why
> my start-up beeps did not sound and just what went wrong.  I
> checked my
> circuitry and found nothing.......I placed my finger on the
> F84 and it was
> very HOT.  I said to myself...hey what's going on
> here........the battery
> pack was backwards (alligator clips).
>
> Bottom line.....what you say has merit.  I never did put in
> any reverse
> polarity protection.  The project is supose to run until the
> batteries are
> depleted and it is a low cost device.  I could not afford a
> voltage drop.
>
> 3 volts would probably have minimal effect, except killing
> the batteries :)
>
> David
>
>
> ----- Original Message -----
> From: Tony Nixon <Tony.Nixon@ENG.MONASH.EDU.AU>
> To: <PICLIST@MITVMA.MIT.EDU>
> Sent: Monday, May 31, 1999 6:31 PM
> Subject: Re: Reverse Polarity Protection for 3V PIC Circuit.
>
>
> > Peter Homann wrote:
> > >
> > > Hi,
> > >
> > > I need to protect my PIC16LF84 against reverse polarity.
> Currently I'm
> > > running the circuit of 2 x 1.5 N cells (2/3 AAA). I want
> to protect the
> > > circuitry from the batteries being inserted the wrong way.
> >
> > Just a thought,
> >
> > I wonder if the PIC will be damaged at all with a 3V
> reversed battery.
> >
> > Every protection diode on the IO pins will be conducting
> between VCC and
> > GND rails in the chip, thus trying to drop the battery
> voltage to around
> > 1.2V.
> >
> > Maybe no damaging current is available to flow into the
> chips' 'guts'.
> >
> > Perhaps a simple resistor in series with VCC will suffice
> to limit this
> > current.
> >
> > Maybe this is why I have not damaged 16F84's by inserting
> them into a
> > socket the wrong way around.
> >
> > --
> > Best regards
> >
> > Tony
> >
> > PicNPoke - Multimedia 16F84 Beginners PIC Tools.
> >
> > http://www.picnpoke.com
> > Email picnpoke@cdi.com.au
> >
>