Top octave dividers: A few ideas

Rene Schmitz uzs159 at uni-bonn.de
Fri Nov 5 19:05:17 CET 1999


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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