> -----Original Message-----
> From: Quah [SMTP:asiact@TM.NET.MY]
> Sent: Friday, April 25, 2003 10:14 AM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Re: [EE]: 7812 Unstable
>
> Thanks everyone for providing me ideas and solution on the previous
> issue.
>
> OK, the output capacitor issue is solved. The solution is not to use EL
> Cap at the output cap, it will cause instability.
>
No, that's not the issue.  You can use an electrolytic cap out the output as
long as you have a suitable bypass cap on the input.  Because you have a
long length of wire between your supply and the regulator with ascociated
resiatance and inductance, you are alamost certainly to get instability if
you don't decouple it properly.

Why are you worried about a bypass capacitor shorting?  If you spec it
properly (i.e. voltage margin of around 2x) there is minimal risk of
shorting.  Don't use a tantalum cap if you are worried about reliability.


Regards

Mike


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