[sdiy] PLL question

[Scott Gravenhorst]

Here is what the Fairchild data sheet for the 4046 says about phase shift and
phase comparator II:

"Phase comparator II is an edge-controlled digital memory
network. It provides a digital error signal (phase comp. II
Out) and lock-in signal (phase pulses) to indicate a locked
condition and maintains a 0° phase shift between signal
input and comparator input."

This would indicate that if phase comp 2 is used, the output signal should
stay in lock step with the input.


"Michael Ruberto" <frankentron at hotmail.com> wrote:
>Hmmmm, phase shift should be a 4 letter word ;-) I guess if the phase shift 
>is 180 degrees I'll wind up with alternating 1/8 notes, or more specifically 
>16th notes when the 2 machines play together (only the sequencer responds to 
>start/stop). maybe it would make sense to derive the 24PPQ from the 12Xclock 
>for the sequencer. this will complicate things a bit but in the end I would 
>have synchronized machines right?
>
>~M
>
>
>>From: Tim Ressel <madhun2001 at yahoo.com>
>>To: Michael Ruberto <frankentron at hotmail.com>, synth-diy at dropmix.xs4all.nl
>>Subject: Re: [sdiy] PLL question
>>Date: Mon, 17 Mar 2003 11:51:56 -0800 (PST)
>>
>>Michael,
>>
>>There are two issues here. The first is syncing these
>>two devices. If they both use a MIDI start command,
>>then they will probably be in sync. The second issue
>>has to do with phase shift within the PLL. There is no
>>guarantee that the 12x clock will be in phase with the
>>24PPQ clock. If there is phase shift, then you will
>>see a slight delay.
>>
>>PLLs are pretty easy to make. Whomp one up out of an
>>HC4046 and see how it works.
>>
>>--Tim
>>
>>--- Michael Ruberto <frankentron at hotmail.com> wrote:
>> >
>> > I need to take the 24PPQ from a MIDI to DIN Sync
>> > converter and speed it up
>> > by a factor of 12 with a PLL to clock another device
>> > which requires a higher
>> > clock rate.
>> > Now if I also have a normal sequencer being clocked
>> > by the straight 24PPQ
>> > will it be in perfect sync with the device whos
>> > clock is coming from the
>> > PLL? with a constant tempo, will 1/8 notes generated
>> > from both machines have
>> > acceptable timing to each other assuming the one
>> > device will divide down the
>> > higher clock rate to generate the 1/8 notes?
>> >
>> > I apologize for being so vague but I am just in the
>> > conceptual phase and
>> > haven't put anything to the breadboard yet.
>> >
>> > I appreciate any input :-)
>> >
>> > ~M
>> >
>> >
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