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From: Chris on 26 Feb 2010 23:58
On Feb 24, 1:38 am, "Ban" <bans...(a)web.de> wrote:
> Gerhard Hoffmann wrote:
> > Ban wrote:
> >> Jim Thompson wrote:
> >>> On Wed, 24 Feb 2010 00:34:25 +0100, "Ban" <bans...(a)web.de> wrote:
>
> >>>> Its about the 4046 or equivalent here not your high performance
> >>>> stuff and who says PD2 in a 4046 is an XOR?
>
> >>>> ciao Ban
>
> >>> It's shown that way on the data sheet ??
>
> >> The datasheet says:
> >> Phase comparator 2 is an edge-controlled digital memory
>
> >> network. It consists of four flip-flops, control gating and a
>
> >> 3-state output circuit comprising p and n-type drivers
>
> >> having a common output node. When the p-type or n-type
>
> >> drivers are ON, they pull the output up to VDD or down to
>
> >> VSS respectively. This type of phase comparator only acts
>
> >> on the positive-going edges of the signals at SIGNIN and
>
> >> COMPIN. Therefore, the duty factors of these signals are
>
> >> not of importance.
>
> > Funny how you avoid mentioning PD1.
>
> phase detector one can not give you a lock indication.and there will be
> always a phase angle exept at the center frequency, it's an XOR after all..
> The OP wanted to detect a "locked" condition.
> ciao Ban

I was planning on using comparator II, and after looking a little more
carefully it looks like the phase pulses of pin one could be fed to an
inverter, and in turn to a buffer that would control power to a LED.
The led would be dim when there were many phase pulses, but when the
thing smooths out, the LED would go to full brightness. Just a
thought.

Thanks,
Chris
From: Chris on 27 Feb 2010 00:01
On Feb 23, 11:40 am, "Ban" <bans...(a)web.de> wrote:
> Chris wrote:
> > The data sheet just gives some ancient reference for finding the
> > values for R1, R2, and C1.
>
> > Is the RC network for the VCO is (R1, R2, C1)?  Would I just use the
> > cutoff frequency for the R1 and C2 RC filter (i.e. fc=1/(2*Pi*R1*C1))..
>
> > Thanks,
> > Chris KQ6UP
>
> hmm, you will need also a loop-filter, so it is better to study the data
> sheet until you understand what you are doing.
> ciao Ban

After more careful inspection, I see that the references to the
"ancient" text were for the loop filter. Is there an on-line
reference so that I can find values for the loop filter?

Thanks,
Chris Maness
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