From:   Dave VanHorn[SMTP:dvanhorn@CEDAR.NET]
Sent:   Wednesday, September 24, 2003 4:25 PM
To:     PICLIST@MITVMA.MIT.EDU
Subject:        Re: [EE:]  Newbie Question: Electrical protection for PICs

>
>>I have seen 5.6V zener diodes between +5V and ground on some digital
>>projects to protect logic. The usual motivation is fear that the linear
>>regulator will short, putting the full unregulated DC on the load.

>Does it really save you anything?  Broken is Broken, wether it's one part,
>or 100.

>Certainly you want to prevent catastrophic problems, like fire, but not
>much sense in adding components, which have their own failure rate, to
>protect against the results of failure on the other parts, when the end
>result is that it's still broken.

The idea is to blow the fuse before the zener blows. If it works right,
only the fuse is broken.

John Power

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