Top octave dividers: A few ideas

Paul Maddox Paul.Maddox at unilever.com
Mon Nov 8 09:41:50 CET 1999


Rene,


  Interesting.. divide from 3 - 15999 in the datasheet looks like
a handy kinda chip, looks kinda usefull... 

  I got the datasheet, but Im puzzled, I assume you put the data
on the inputs (J1 - J16) and then you bring the EL line High to write
the data to the latches, and supply CP with a clock, and from O
you get your clock? if this is so, I will be buying about 16 of these
from my drum machine project....

  Paul


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-----Original Message-----
From:	Rene Schmitz [SMTP:uzs159 at uni-bonn.de]
Sent:	Friday, November 05, 1999 6:05 PM
To:	synth-diy at mailhost.bpa.nl
Subject:	Top octave dividers: A few ideas

Hi all!

Anyone considered using the CMOS 4059? Its division can be set using a
4-digit BCD number (1-1000). Interfaceing should be easy to a uC with two
8-bit ports, I don't know if they contain a latch. It can run up to 12Mhz.
Should make a fine DCO. But its out of the question for a TO-divider as
you'd need 12 of them, and they cost about 2.5 EUR here. 

Another idea would be to use twelve fixed frequency oscillators, like two
40106s with caps + resistors. As was pointed out here, these CMOS schmitt
triggers are quite temperature stable. Would allow a precise equally
tempered scale. Tunes like a piano. Output is not a 50% squarewave, but
this doesn't matter as you'll use dividers anyway. 

Last but not least: I saw an octave divider done with a PIC 16C5x but it
was not the top octave. One could use a PLL to shift it a few octaves up.
The PLLs will always be locked, so loop response is not an issue. (The
source is at the site of "The old Crow", see the link at the synth-diy
homepage.)

Bye
 René

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