[sdiy] A440 Reference using 11MHz clock

[James Patchell]

The simple way is not always the best way....I prefer to use synchronous 
counters as they give the cleanest outputs.

But, to each his own.

At 07:16 PM 6/27/2004 +0200, Jaroslaw Ziembicki wrote:
>Hello James and everyone!
>
>One simple way to get 440Hz out from 11MHz is to
>use 2 counters 74HC4040 (CD40404 is too slow!).
>Connect 11MHz to CP(10) of counter1, Q11(1) of
>counter1 to CP(10) of counter2. Then connect each
>of the following pins:
>counter1:  5,2,13,12
>counter2:  7,6
>through a diode (eg. 1N4148) to MR(11) of both chips.
>Each diode is connected with the anode to the counter output
>and with the cathode to both MR's. Also, put a pull-down
>resistor (about 10 k) between both MR's and GROUND.
>So you get a cheap, simple frequency divider.
>The output is: counter2 pin 6.
>It's possible to have another crystal frequencies and just use
>another counters' outputs. Example for 10MHz:
>counter1:  9,7,6,4,13,1
>counter2:  9,6
>output: counter2 pin 6
>The output frequency is 440.0052801 Hz
>(relative error = +0.0012%).
>
>Regards
>Jarek
>
>
>----- Original Message -----
>From: "James Patchell" <patchell at cox.net>
>To: <synth-diy at dropmix.xs4all.nl>
>Sent: Sunday, June 27, 2004 6:23 PM
>Subject: [sdiy] A440 Reference using 11MHz clock
>
>
> > http://www.oldcrows.net/~patchell/div25000.pdf

         -Jim
***************************************************************
http://www.oldcrows.net/~patchell

***************************************************************