What about a polyswitch or a PTC resistor (instead of a fuse or fixed
resistor)
Richard

> -----Original Message-----
> From: Dennis Plunkett [mailto:dennis@RDD.NECA.NEC.COM.AU]
> Sent: Tuesday, June 01, 1999 11:19 AM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: Reverse Polarity Protection for 3V PIC Circuit.
>
>
> At 17:49 31/05/99 -0500, you wrote:
> >I don't agree with the statement that your product has
> failed.  Just the
> >contrary.
>
> No, the product has failed! A blow fuse is a failure it stops working!
> Hence FAILed
>
> >The user has preserved his/her investment in that product.
> The failure is
> >in the
> >user not following instructions in installing the batteries.
>
> There is some argument about service technicians not being
> able to change a
> set of torch batteries without an instructiion manual
> appicable here, be
> dammed if I can remember it :)
>
>
> > If they would
> >have been
> >paying attention, they wouldn't have put the batteries in
> backwards, and
> >they
> >would not have had the inconvienence of a blown fuse.  But
> they only lost a
> >fuse
> >and a little time, not the whole unit.
> >
>
> Fuses in battery operated devices (Hand held) since when?
>
>
> >As far as not being servicable by the user, how much education and
> >coordination
> >does it take to change a fuse.
>
> An IQ or more than moron level perhaps?
>
> >It would have taken less time to pay
> >attention to
> >the battery installation instructions in the first place,
> thereby saving
> >time and trouble.
> >
>
> If they can get the batteries wrong, then why do you assume that the
> operator can get a fuse correct?
> What is stopping the operator from changing it to a higher
> rating say a 3"
> nail?
>
>
> >The end choice is up to the designer.  I only offered a
> suggestion.  One
> >that has been
> >used and proven by me.  It is there for you to consider.
> Whether you use it
> >in your end
> >product is totally up to you.
>
>
> All suggestions are open to comment. Sometimes there may be a
> better mouse
> trap out there, never hurts to check. (Snap!)
>
>
> >Whatever  failsafe method is chosen, as long
> >as it provides
> >the degree of safety necessary, and at a cost that is
> agreeable by everyone
> >involved, is
> >the right choice for that product.
> >
>
> Fuses and fuse holders are expesnsive, yet alone all the
> abuse that you cop
> when a fuse blows (Operator error or not)
>
>
> Dennis
>
> >I guess I'm done now.   Thanks for letting me sound off on
> what I think
> >regarding this issue.
> >
> >
> >Good Luck,
> >
> >
> >Jim
> >
> >
> >-----Original Message-----
> >From: Paul B. Webster VK2BZC <paulb@midcoast.com.au>
> >To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
> >Date: Monday, May 31, 1999 5:25 PM
> >Subject: Re: Reverse Polarity Protection for 3V PIC Circuit.
> >
> >
> >>Jim Paul wrote:
> >>
> >>> You could add a diode across the batteries with a fuse so
> that is the
> >>> batteries are inserted the wrong way, the fuse blows
> cutting off the
> >>> power source.
> >>
> >>  But then your appliance has "failed".  Not good
> publicity.  OK, if it
> >>is used under supervision and can be repaired and put back
> into service.
> >>Better to use a resistor (only need a few ohms) and diode.
> >>
> >>  Reverse-inserted batteries promptly go flat.  "Darn batteries!"
> >>Properly inserted ones last for "ages".  Appliance always works if
> >>good batteries inserted correctly.  This is the "teaching" approach.
> >>--
> >>  Cheers,
> >>        Paul B.
> >
> >
>