# CMOS Divide by 5.9 Cicuit

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I have a CD4060 that uses a 32,768Hz crystal to generate a 32Hz square
wave.

I would like to divide this down several times in 5.9Hz increments,
while keeping the duty cycle at 50%.

What would be the most straightforward method, preferably keeping in
CMOS?

Ken Knowles

Re: CMOS Divide by 5.9 Cicuit

in software using "bit bang" method.

--
Dipl.-Inform(FH) Peter Heitzer, snipped-for-privacy@rz.uni-regensburg.de
HTML mails will be forwarded to /dev/null.

Re: CMOS Divide by 5.9 Cicuit
On 20 Aug 2014 08:51:01 GMT, "Peter Heitzer"

I am sorry my orignal explanation was unclear to some readers.

It is easy to generate 32Hz with a 32,768 clock crystal and a CD4060.

I then would like to produce from this four or five frequencies that
all differ by the same number of Hz.

To take a simple example, if that was 4Hz I would get 28, 24, 20,
16Hz, and so on.

Since coding is not one of my skills, can this be done with logic
IC's? Maybe something involving sums and differences.

I could also use a separate generator for each frequency, but was
hoping for a more efficient method, if there is one.

Ken Knowles

Re: CMOS Divide by 5.9 Cicuit

Still not real clear.

since a crystal is a crystal and soundcards use crystal clock, you could
directly drive a soundcard generate your tone(s) individually or all at
once.

You can get really fine steps that way

Re: CMOS Divide by 5.9 Cicuit
On 20/08/14 23:14, Ken Knowles wrote:

So, in clear language, you'd like to create 32Hz, 26.1Hz, 20.2Hz,
14.3Hz, etc, down to ???, from one 32768Hz source, all with 50%
duty cycle. That's probably not trivial in old-fashioned logic,
but a multiple DDS algorithm in a tiny microcontroller could come
pretty close with relative ease.

Do you mind telling us why you want to do so? Often the *real*
problem is easier to solve that someone's weird idea of a
solution.

Jeroen Belleman

Re: CMOS Divide by 5.9 Cicuit
On Wed, 20 Aug 2014 23:45:12 +0200, jeroen Belleman

Since I don't have coding skills, it seems the opnly viable solutuion
is to build a separate generator for each frequency.

Thanks to all for the helpful suggestions.

Ken Knowles

Re: CMOS Divide by 5.9 Cicuit

Since I don't have coding skills, it seems the opnly viable solutuion
is to build a separate generator for each frequency. "

Are you measuring output from subwoofers ?

If you are trying to get better than the pink noise method, you have to filter the input, to where it does not pick up harmnics of the frequency put into the woofer.

If the application is something else, sorry to waste your time.

but I did not notice the exact purpose of this device. Maybe you got your reasons.

Re: CMOS Divide by 5.9 Cicuit
On Wednesday, August 20, 2014 7:04:14 PM UTC-7, Ken Knowles wrote:

The problem is, 32 Hz has a period of 0.312500 seconds, which is
1024 'ticks' of a 32768 Hz clock.  And 26.1 Hz has a period of
.03831417625 seconds, which is 1255.478927.. ticks of that clock.  There's
no digital way to directly generate frequencies without approximations,
unless the frequencies of interest line up 'just right' with your digital
clock.

Re: CMOS Divide by 5.9 Cicuit
wrote:

This could be solved by using numerically controlled oscillators
http://en.wikipedia.org/wiki/Numerically_controlled_oscillator in
which there is an NCO for each frequency.

For square output, but approximately 50 % duty cycle digital output,
you could use the highest bit of the phase accumulator as the digital
output.

For sine wave output, use the highest bits of the phase accumulator to
address a sine table and use the acquired value to run a DAC/PWM
output and some passive RC filtering for clean sine wave.

Of course, this can be done with CD4000 series chips, but the cost
will increase rapidly with the number of frequencies required.

If you are not familiar with microconrollers, this might be a good
opportunity to learn how to do some simple things using a
microcontroler.

You would need a very primitive microcontroller clocked at about 1-3
MHz from any free running oscillator. The 16 to 32 bit phase
accumulators are updated each time the 32768 Hz precise oscillator
changes state. For digital output, you need just one digital output
pin, for analog output, he chips should have pins with DAC or PWM
outputs.

software accumulator (2 to 4 bytes) and one output pin (or even less,
if an external analog/digital demultiplexer is used.

Re: CMOS Divide by 5.9 Cicuit
On Thu, 21 Aug 2014 07:14:07 +1000, Ken Knowles wrote:

4Hz is much easier than 5.9.

You need to use a 4046 or other PLL chip, and synthesize multiples of some
reference frequency.  Then either use that, or divide it down to your
desired frequency.

To get 4, 8, 12, etc., you probably want to synthesize multiples of your
crystal clock (so your PLL will settle quickly), then divide the result
down.

Google "frequency synthesis".  The short story is that you take the output
of the PLL chip and divide it by n, then phase lock the (PLL/n) signal to
the reference.  As long as the PLL stays locked, its output will be n *
reference.  There's all sorts of jiggery-pokery you'll need to do to get
the PLL to work right, compounded by the fact that the easily available
4046 derivatives have oscillators that tend to misbehave at low

You're probably looking at a 74HCU04 for the reference oscillator, a
74HC4046 PLL, a 74HC161 divider chip, some NAND gates (I vaguely recall
that you need them if you want to turn the '161 into a divide-by-n chip),

Or, you can do it all with an 8-pin PIC or other 8-pin microprocessor:

--

Tim Wescott
Wescott Design Services
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Re: CMOS Divide by 5.9 Cicuit

the simpler solution is a microcontroller with "four or five" 16-bit
counters that can drive output pins,

I think atmel do some 8 some bit AVR microcontrollers with 4 to 6
counters

however it's a bit more delicate, it won't run off 3 to 15V like tha
4060 does,  And while it doesn't use a lot of power, it still uses more
than the 4060. even with the core halted and only the counters running

another option is a microcontroller running off a faster clock and doing
the frewquency division in software, it'll use more power, be harder to
program, but may allow cheaper parts.

--
umop apisdn

Re: CMOS Divide by 5.9 Cicuit
On 22 Aug 2014 11:21:17 GMT, the renowned Jasen Betts

Or just get one or two frequencies from a microcontroller, in which
case there are many choices. Computers are cheap in 2014, no need to
make them do a lot of work.

For example, a PIC18F24J10 can generate two frequencies from a 10MHz
clock for ~\$1.50 each in 25's. The compare registers are only 16 bits
so you'd have to count hits to get 100ns resolution at 16Hz, but
that's just a few lines of code.

Best regards,
Spehro Pefhany
--
"it's the network..."                          "The Journey is the reward"
snipped-for-privacy@interlog.com             Info for manufacturers: http://www.trexon.com
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Re: CMOS Divide by 5.9 Cicuit
wrote:

If you do not want to use a microcontroller and the NCO principle, you
are forced to divide down to the frequency spacing frequency (4 Hz or
32 Hz) and then use individual PLLs for each frequency.

In practical circuits, use something like 256x or 1000x reference
frequency and then use the same amount of division after _each_  PLL.

Re: CMOS Divide by 5.9 Cicuit
On 20 Aug 2014 08:51:01 GMT, "Peter Heitzer"

I think I may have figured out a way to get something close to the
result I am looking for.

The CD4060 with a 32,768Hz crystal will output a 32, and 8Hz
squarewave.

If I filter these into sine waves, what is the procedure for having
them along with their sum and difference frequencies all together in
one signal?

IOW to end up with a repetitive arbitrary waveform comprised of 40,
32, 27  and 8Hz.

Ken Knowles

Re: CMOS Divide by 5.9 Cicuit

take 32 and 'multiply' it 8 in something like a MC1496

if done well, that will produce 40, 32, 27, and 8

a MUCH simpler way is to drive your stupid soundcard with a .wav
repetitively. use the standard 48kS/s to be an EXACT multiple, use octave
to make the .wav file and you can get equal amplitude ANY phase you want,
complete control and not even have to breadboard anything. All these tools
are FREE to work with, too.

Re: CMOS Divide by 5.9 Cicuit
wrote:

arrrggg! that was NOT handwritten, just NO excuse!  not 27, but 24

Re: CMOS Divide by 5.9 Cicuit

Completely the wrong approach.

Assuming it is *ESSENTIAL* to lock the frequency to the 32768 Hz crystal,
I'd start by squaring it up and doubling the frequency with a RC delay
and an XOR.  Then use a programmable divider chip (or rather chips as
you'll probaby need to cascade them) to get pulses at a rate as close as
possible to N*11.8 Hz.

Finaly a flipflop divides by two to get a good square wave.

If you dont need to start with 32768 Hz, its much more accurate if you
use a significantly higher crystal frequency - at the expense of needing
a longer divider chain and more bits for the division ratio to program
it.

You need some way of storing the division ratio which could be programmed
with a hard wired diode matrix + a 10 way rotary switch (for n=1 to 10)
to ground one column at a time of the matrix, with the rows giving the
binary division ratio.

Ditch the 4060, its no help at all. The oscillator can be built from the
spare gates on the XOR.

However all this grief and considerable expense could be avoided if you
can call in any favours to get someone to write a suitable program for a
small PIC and program one for you.
--
Ian Malcolm.   London, ENGLAND.  (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
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Re: CMOS Divide by 5.9 Cicuit

I hope you meant 24, not 27.

This is NOT a digital composition.  A roughly square waveform may be
possible that contains arbitrarily few lower harmonics (e.g., a magic
sinewave approximation), but I doubt it is near trivial to compose from
the source frequencies alone.

You've also suddenly changed your requirement, as I don't see how 40, 32,
24 (or 27) or 8 have anything whatsoever to do with 5.9 as a subtractive
or divisive factor.

Perhaps if you could tell us a little about the underlying enigmatic
purpose, we could suggest something both better suited and easier to
construct.

Tim

--
Seven Transistor Labs
Electrical Engineering Consultation
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Re: CMOS Divide by 5.9 Cicuit

Tim

--
Seven Transistor Labs
Electrical Engineering Consultation
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Re: CMOS Divide by 5.9 Cicuit
On 2014-08-21 04:50, Ken Knowles wrote:

Oh, that's very different from what you asked for at the start.

This is a waste of time. Tell us what you're really trying to
do or go away.

Jeroen Belleman