Re: pic a/d problems

From: timmmmayyy! (timmmmayyy_at_nospamplease.com)
Date: 10/26/04 

Date: Tue, 26 Oct 2004 13:02:31 +0100

I found that one op amp output was giving 7.5v to another a/d pin, reduced
this and the chip was back on spec.

I have yet to find a 7805 regulator that supplies over stated voltage. I
normally find it is at least 4.9.

I think it is only the cheaper regs that have a 4% tolerence.

timmayy

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:pLdfd.9932$6q2.6300@newssvr14.news.prodigy.com...
> Hi Frank,
>
> >Then I would check if the supply voltages are different. A 7805 regulator
> >for instance, can vary between 4.8 and 5.2V. (+/- 4%). Your readings of
79
> >and 83 are +/- 2.5% of 81.
> >
> >
> Good point. It would also be a good idea to hook a scope probe to the
> supply and center trigger on the AD conversion event. It is often
> surprising what goes on there. Even the tolerance of a decoupling cap
> that was kind of borderline smallish can have an effect on load recovery.
>
> Regards, Joerg
>
> http://www.analogconsultants.com

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