Is a Gray code counter more energy efficient?...

[Martin Brown]

On 18/06/2023 03:18, whit3rd wrote:

On Saturday, June 17, 2023 at 11:26:09 AM UTC-7, Ricky wrote:
On Saturday, June 17, 2023 at 12:16:38 PM UTC-4, whit3rd wrote:

[about Accutron DNA watch]
The minute-hand \'tick\' is the slowest clock required for that watch (with minutes/hours
being gear-connected). A crystal with power-of-two division to minutes(rather than seconds)
would be expected; nearest to the common 32768 Hz would be 30720 Hz.
Digikey doesn\'t stock that particular value, though: it\'d be a custom rock.

Why are you so afraid of divide by 60? It is trivial as /6 /10 with
classical digital hardware chips. Or /3 /4 /5 depending on your outlook.

That is why the Babylonians so liked base 60!

32kHz is so slow that you don\'t need to worry about power consumption at
all unless you really cock things up.

The lowest power divider will be a ripple counter where each stage is clocked by the output of the previous stage. You can\'t just compare the mode of the counters, you also need to compare the implementation.

The crystal frequency is not important. As you say, custom frequencies can be obtained. However, I\'m not sure of the cost. It seems frequencies around 32.768 kHz are very, very rare and I expect you need to buy a large number of units to lower the price of such a frequency.

In the old days of AT-cut disks, that would be correct (off-spec units for TV colorburst made
it very inexpensive to get 4 MHz rocks). The tuning-fork crystals at 32 kHz, though,
are cut to rough frequency, then tuned by metal-plating the tines\' ends. It\'d be trivial to rescale,
and yields are high because the plating is an easy-to-adjust trim (adding thickness to a
ground-down quartz disk, is NOT easy).

I recall someone (an astronomer) who long ago had a batch of ~10k
crystals cut to sidereal time faster than mean solar time by 3m 56s per
day. ISTR it was a minimum order of 10k units.

They were all long gone when I wanted one so I did it by fiddling the
divisor. First tuned to exact mean solar time and offset from that.

--
Martin Brown

 

[Ricky]

On Sunday, June 18, 2023 at 4:17:46 PM UTC-4, whit3rd wrote:

On Sunday, June 18, 2023 at 1:01:59 AM UTC-7, Ricky wrote:

But this is all academic, since you aren\'t actually building anything.
So, what\'s wrong with that? I\'m analyzing, to learn something new.

I didn\'t say anything was wrong. It\'s just that you can\'t actually do a decent design since there are no constraints, no purpose. When you first posted, I thought you were trying to do something. In reality, none of the thoughts about the digital logic have any meaning, since we know nothing of the constraints. There\'s many, many ways to skin this cat, and which is lowest power depends on which are practical.

The real power consumption is in moving the second hand. I\'m not sure how well you can minimize that. Is the second hand on the Accutron balanced? I think I posted about my $10 digital wall clock that gets 50% more days from the battery after adding a crude balance on the second hand.

I did a search for the term of this balance, but never came up with anything. The way virtually ever part of a clock has a specific term makes me think there is a term for this, but I\'ve simply not found it.

--

Rick C.

+++ Get 1,000 miles of free Supercharging
+++ Tesla referral code - https://ts.la/richard11209

 

[whit3rd]

On Sunday, June 18, 2023 at 1:25:15 PM UTC-7, Martin Brown wrote:

On 18/06/2023 03:18, whit3rd wrote:
On Saturday, June 17, 2023 at 11:26:09 AM UTC-7, Ricky wrote:
On Saturday, June 17, 2023 at 12:16:38 PM UTC-4, whit3rd wrote:

[about Accutron DNA watch]
The minute-hand \'tick\' is the slowest clock required for that watch (with minutes/hours
being gear-connected). A crystal with power-of-two division to minutes(rather than seconds)
would be expected; nearest to the common 32768 Hz would be 30720 Hz.
Digikey doesn\'t stock that particular value, though: it\'d be a custom rock.

Why are you so afraid of divide by 60? It is trivial as /6 /10 with
classical digital hardware chips. Or /3 /4 /5 depending on your outlook.

That is why the Babylonians so liked base 60!

The second hand is NOT stepping at 1 Hz, though; it\'s a synchronous electrostatic motor,
so there\'s no benefit to \'dividing down\' to one-per-second, rather one can just factor
any 2^N precursor of the one minute clock, and use a number of poles and
phases for the drive to accomplish the smooth sweep hand motion.

Two pole pairs and 60 Hz (60 cycles/sec) electricity makes for a 1800 RPM (30 rotations/sec) motor;
the \'divide by two\' was just done by having that many poles and two 60 Hz phases. No dividers.

 

[Brian Gregory]

On 13/06/2023 16:57, whit3rd wrote:

Generating a one-Hz second hand drive would work OK from a 32727 Hz quartz
crystal with pseudorandom division, rather than the more common 32728 Hz value.

32768 Hz is the normal watch crystal frequency.

--
Brian Gregory (in England).

 

[whit3rd]

On Sunday, June 18, 2023 at 3:56:45 PM UTC-7, Brian Gregory wrote:

On 13/06/2023 16:57, whit3rd wrote:
Generating a one-Hz second hand drive would work OK from a 32727 Hz quartz
crystal with pseudorandom division, rather than the more common 32728 Hz value.
32768 Hz is the normal watch crystal frequency.

It\'s \'normal\' for a clock that does one step per second; there\'s no use for one-per-second
increments for a multiphase motor with one minute per revolution. The one-minute hand
is the only ticking item in this timepiece.

32737 Hz actually IS stocked; that might be useful in a pseudorandom sequence for 1 second
where the \'countdown\' isn\'t by binary division (flipflops).

 

[Ricky]

On Sunday, June 18, 2023 at 11:38:43 PM UTC-4, whit3rd wrote:

On Sunday, June 18, 2023 at 3:56:45 PM UTC-7, Brian Gregory wrote:
On 13/06/2023 16:57, whit3rd wrote:
Generating a one-Hz second hand drive would work OK from a 32727 Hz quartz
crystal with pseudorandom division, rather than the more common 32728 Hz value.
32768 Hz is the normal watch crystal frequency.
It\'s \'normal\' for a clock that does one step per second; there\'s no use for one-per-second
increments for a multiphase motor with one minute per revolution. The one-minute hand
is the only ticking item in this timepiece.

32737 Hz actually IS stocked; that might be useful in a pseudorandom sequence for 1 second
where the \'countdown\' isn\'t by binary division (flipflops).

Uh, how do you count down without using flipflops?

--

Rick C.

---- Get 1,000 miles of free Supercharging
---- Tesla referral code - https://ts.la/richard11209

 

[whit3rd]

On Sunday, June 18, 2023 at 8:47:48 PM UTC-7, Ricky wrote:

On Sunday, June 18, 2023 at 11:38:43 PM UTC-4, whit3rd wrote:
On Sunday, June 18, 2023 at 3:56:45 PM UTC-7, Brian Gregory wrote:
On 13/06/2023 16:57, whit3rd wrote:
Generating a one-Hz second hand drive would work OK from a 32727 Hz quartz
crystal with pseudorandom division, rather than the more common 32728 Hz value.
32768 Hz is the normal watch crystal frequency.
It\'s \'normal\' for a clock that does one step per second; there\'s no use for one-per-second
increments for a multiphase motor with one minute per revolution. The one-minute hand
is the only ticking item in this timepiece.

32737 Hz actually IS stocked; that might be useful in a pseudorandom sequence for 1 second
where the \'countdown\' isn\'t by binary division (flipflops).

Uh, how do you count down without using flipflops?

Shift register, gates determine the inshifted bit... there\'s latched bits (flipflops, if you will)
but not \'toggle\' control of them. The pseudorandom sequence generated only goes
to all-ZERO outputs once per cycle, but cannot do all-ONE outputs without stalling.
So, it cannot do divide-by-2^N, but at most divide-by-((2^N) -1).

 

[Ricky]

On Monday, June 19, 2023 at 12:21:23 AM UTC-4, whit3rd wrote:

On Sunday, June 18, 2023 at 8:47:48 PM UTC-7, Ricky wrote:
On Sunday, June 18, 2023 at 11:38:43 PM UTC-4, whit3rd wrote:
On Sunday, June 18, 2023 at 3:56:45 PM UTC-7, Brian Gregory wrote:
On 13/06/2023 16:57, whit3rd wrote:
Generating a one-Hz second hand drive would work OK from a 32727 Hz quartz
crystal with pseudorandom division, rather than the more common 32728 Hz value.
32768 Hz is the normal watch crystal frequency.
It\'s \'normal\' for a clock that does one step per second; there\'s no use for one-per-second
increments for a multiphase motor with one minute per revolution. The one-minute hand
is the only ticking item in this timepiece.

32737 Hz actually IS stocked; that might be useful in a pseudorandom sequence for 1 second
where the \'countdown\' isn\'t by binary division (flipflops).

Uh, how do you count down without using flipflops?
Shift register, gates determine the inshifted bit... there\'s latched bits (flipflops, if you will)
but not \'toggle\' control of them. The pseudorandom sequence generated only goes
to all-ZERO outputs once per cycle, but cannot do all-ONE outputs without stalling.
So, it cannot do divide-by-2^N, but at most divide-by-((2^N) -1).

Sorry, I have no idea what you are trying to say about this. So they use FFs. Glad we have that clear. I\'m familiar with pseudo random sequences, but what advantage to they provide here?

It is not a general truth that the fact of calculating only one FF input with gates, means it will be lower power than other counters. As I\'ve already explained, the binary ripple counter should have the lowest power consumption of any counter type, given that none of the inputs require logic and the transitions of FFs average 2N per clock cycle. It could be second to a gray coded counter (N FF transitions per clock cycle) if the impact on power of the FF outputs is much more significant than the logic gates themselves. But this ALWAYS depends on the details of the logic implementation. If you use boulders and donkeys for implementing FFs, all bets are off.

--

Rick C.

---+ Get 1,000 miles of free Supercharging
---+ Tesla referral code - https://ts.la/richard11209

 

[whit3rd]

On Sunday, June 18, 2023 at 9:36:03 PM UTC-7, Ricky wrote:

On Monday, June 19, 2023 at 12:21:23 AM UTC-4, whit3rd wrote:
On Sunday, June 18, 2023 at 8:47:48 PM UTC-7, Ricky wrote:
On Sunday, June 18, 2023 at 11:38:43 PM UTC-4, whit3rd wrote:
On Sunday, June 18, 2023 at 3:56:45 PM UTC-7, Brian Gregory wrote:
On 13/06/2023 16:57, whit3rd wrote:
Generating a one-Hz second hand drive would work OK from a 32727 Hz quartz
crystal with pseudorandom division, rather than the more common 32728 Hz value.
32768 Hz is the normal watch crystal frequency.
It\'s \'normal\' for a clock that does one step per second; there\'s no use for one-per-second
increments for a multiphase motor with one minute per revolution. The one-minute hand
is the only ticking item in this timepiece.

32737 Hz actually IS stocked; that might be useful in a pseudorandom sequence for 1 second
where the \'countdown\' isn\'t by binary division (flipflops).

Uh, how do you count down without using flipflops?
Shift register, gates determine the inshifted bit... there\'s latched bits (flipflops, if you will)
but not \'toggle\' control of them. The pseudorandom sequence generated only goes
to all-ZERO outputs once per cycle, but cannot do all-ONE outputs without stalling.
So, it cannot do divide-by-2^N, but at most divide-by-((2^N) -1).

Sorry, I have no idea what you are trying to say about this. So they use FFs. Glad we have that clear. I\'m familiar with pseudo random sequences, but what advantage to they provide here?

We do NOT have that clear; a CCD (like the shift-bits-out action in a camera sensor) also implements
a shift register, without a true flip-flop. It takes clocking, and some kind of latch, but the
static memory of a flip flop and the dynamic memory of a CCD are both suitable bit storage elements.

The dynamic RAM power utilization advantage over static RAM is the possible advantage.

 

[Jan Panteltje]

On a sunny day (Sun, 18 Jun 2023 20:47:44 -0700 (PDT)) it happened Ricky
<gnuarm.deletethisbit@gmail.com> wrote in
<83110f6f-e327-443e-bd6e-3c36a3ccaec1n@googlegroups.com>:

>Uh, how do you count down without using flipflops?

Use your fingers

 

[Ricky]

On Monday, June 19, 2023 at 12:45:39 AM UTC-4, whit3rd wrote:

On Sunday, June 18, 2023 at 9:36:03 PM UTC-7, Ricky wrote:
On Monday, June 19, 2023 at 12:21:23 AM UTC-4, whit3rd wrote:
On Sunday, June 18, 2023 at 8:47:48 PM UTC-7, Ricky wrote:
On Sunday, June 18, 2023 at 11:38:43 PM UTC-4, whit3rd wrote:
On Sunday, June 18, 2023 at 3:56:45 PM UTC-7, Brian Gregory wrote:
On 13/06/2023 16:57, whit3rd wrote:
Generating a one-Hz second hand drive would work OK from a 32727 Hz quartz
crystal with pseudorandom division, rather than the more common 32728 Hz value.
32768 Hz is the normal watch crystal frequency.
It\'s \'normal\' for a clock that does one step per second; there\'s no use for one-per-second
increments for a multiphase motor with one minute per revolution. The one-minute hand
is the only ticking item in this timepiece.

32737 Hz actually IS stocked; that might be useful in a pseudorandom sequence for 1 second
where the \'countdown\' isn\'t by binary division (flipflops).

Uh, how do you count down without using flipflops?
Shift register, gates determine the inshifted bit... there\'s latched bits (flipflops, if you will)
but not \'toggle\' control of them. The pseudorandom sequence generated only goes
to all-ZERO outputs once per cycle, but cannot do all-ONE outputs without stalling.
So, it cannot do divide-by-2^N, but at most divide-by-((2^N) -1).

Sorry, I have no idea what you are trying to say about this. So they use FFs. Glad we have that clear. I\'m familiar with pseudo random sequences, but what advantage to they provide here?
We do NOT have that clear; a CCD (like the shift-bits-out action in a camera sensor) also implements
a shift register, without a true flip-flop. It takes clocking, and some kind of latch, but the
static memory of a flip flop and the dynamic memory of a CCD are both suitable bit storage elements.

The dynamic RAM power utilization advantage over static RAM is the possible advantage.

I have no idea what you are talking about. If you want to explain it, fine.. But continuing to pull stuff from your back pocket is pointless.

I guess this all comes from having no indicated purpose to your exploration.. So everything is an option. Whatever. When are you going to talk about moon rocks?

--

Rick C.

--+- Get 1,000 miles of free Supercharging
--+- Tesla referral code - https://ts.la/richard11209

 

[whit3rd]

On Sunday, June 18, 2023 at 11:03:50 PM UTC-7, Ricky wrote:

On Monday, June 19, 2023 at 12:45:39 AM UTC-4, whit3rd wrote:
On Sunday, June 18, 2023 at 9:36:03 PM UTC-7, Ricky wrote:
On Monday, June 19, 2023 at 12:21:23 AM UTC-4, whit3rd wrote:
On Sunday, June 18, 2023 at 8:47:48 PM UTC-7, Ricky wrote:
On Sunday, June 18, 2023 at 11:38:43 PM UTC-4, whit3rd wrote:
On Sunday, June 18, 2023 at 3:56:45 PM UTC-7, Brian Gregory wrote:

32768 Hz is the normal watch crystal frequency.

It\'s \'normal\' for a clock that does one step per second; ...
32767 Hz actually IS stocked; that might be useful in a pseudorandom sequence for 1 second
where the \'countdown\' isn\'t by binary division (flipflops).

Uh, how do you count down without using flipflops?

Shift register, gates determine the inshifted bit... there\'s latched bits (flipflops, if you will)
but not \'toggle\' control of them. The pseudorandom sequence generated only goes
to all-ZERO outputs once per cycle, but cannot do all-ONE outputs without stalling.
So, it cannot do divide-by-2^N, but at most divide-by-((2^N) -1).

Sorry, I have no idea what you are trying to say about this. So they use FFs. Glad we have that clear. I\'m familiar with pseudo random sequences, but what advantage to they provide here?

We do NOT have that clear; a CCD (like the shift-bits-out action in a camera sensor) also implements
a shift register, without a true flip-flop. It takes clocking, and some kind of latch, but the
static memory of a flip flop and the dynamic memory of a CCD are both suitable bit storage elements.

The dynamic RAM power utilization advantage over static RAM is the possible advantage.

I have no idea what you are talking about. If you want to explain it, fine. But continuing to pull stuff from your back pocket is pointless.

I guess this all comes from having no indicated purpose to your exploration. So everything is an option. Whatever. When are you going to talk about moon rocks?

You quoted (above) my statement that in addition to 32768 Hz, there were 32767Hz (I typo\'ed the
number...) oscillators

<https://www.digikey.com/en/products/detail/renesas-electronics-america-inc/XUH536000-032767I/12753965>

available; I then suggested a use to which the latter might apply, and
that it would have different energy cost seems likely. The mystery of
a (2^15 - 1 ) Hz oscillator\'s purpose is open to other explanations: what\'s yours?

 

[Ricky]

On Monday, June 19, 2023 at 2:41:21 AM UTC-4, whit3rd wrote:

On Sunday, June 18, 2023 at 11:03:50 PM UTC-7, Ricky wrote:
On Monday, June 19, 2023 at 12:45:39 AM UTC-4, whit3rd wrote:
On Sunday, June 18, 2023 at 9:36:03 PM UTC-7, Ricky wrote:
On Monday, June 19, 2023 at 12:21:23 AM UTC-4, whit3rd wrote:
On Sunday, June 18, 2023 at 8:47:48 PM UTC-7, Ricky wrote:
On Sunday, June 18, 2023 at 11:38:43 PM UTC-4, whit3rd wrote:
On Sunday, June 18, 2023 at 3:56:45 PM UTC-7, Brian Gregory wrote:

32768 Hz is the normal watch crystal frequency.
It\'s \'normal\' for a clock that does one step per second; ...
32767 Hz actually IS stocked; that might be useful in a pseudorandom sequence for 1 second
where the \'countdown\' isn\'t by binary division (flipflops).

Uh, how do you count down without using flipflops?

Shift register, gates determine the inshifted bit... there\'s latched bits (flipflops, if you will)
but not \'toggle\' control of them. The pseudorandom sequence generated only goes
to all-ZERO outputs once per cycle, but cannot do all-ONE outputs without stalling.
So, it cannot do divide-by-2^N, but at most divide-by-((2^N) -1).

Sorry, I have no idea what you are trying to say about this. So they use FFs. Glad we have that clear. I\'m familiar with pseudo random sequences, but what advantage to they provide here?

We do NOT have that clear; a CCD (like the shift-bits-out action in a camera sensor) also implements
a shift register, without a true flip-flop. It takes clocking, and some kind of latch, but the
static memory of a flip flop and the dynamic memory of a CCD are both suitable bit storage elements.

The dynamic RAM power utilization advantage over static RAM is the possible advantage.

I have no idea what you are talking about. If you want to explain it, fine. But continuing to pull stuff from your back pocket is pointless.

I guess this all comes from having no indicated purpose to your exploration. So everything is an option. Whatever. When are you going to talk about moon rocks?
You quoted (above) my statement that in addition to 32768 Hz, there were 32767Hz (I typo\'ed the
number...) oscillators

https://www.digikey.com/en/products/detail/renesas-electronics-america-inc/XUH536000-032767I/12753965

available; I then suggested a use to which the latter might apply, and
that it would have different energy cost seems likely. The mystery of
a (2^15 - 1 ) Hz oscillator\'s purpose is open to other explanations: what\'s yours?

I have no idea what you are talking about. Sorry.

--

Rick C.

--++ Get 1,000 miles of free Supercharging
--++ Tesla referral code - https://ts.la/richard11209

 

[Martin Brown]

On 18/06/2023 22:01, whit3rd wrote:

On Sunday, June 18, 2023 at 1:25:15 PM UTC-7, Martin Brown wrote:
On 18/06/2023 03:18, whit3rd wrote:
On Saturday, June 17, 2023 at 11:26:09 AM UTC-7, Ricky wrote:
On Saturday, June 17, 2023 at 12:16:38 PM UTC-4, whit3rd wrote:

[about Accutron DNA watch]
The minute-hand \'tick\' is the slowest clock required for that watch (with minutes/hours
being gear-connected). A crystal with power-of-two division to minutes(rather than seconds)
would be expected; nearest to the common 32768 Hz would be 30720 Hz.
Digikey doesn\'t stock that particular value, though: it\'d be a custom rock.

Why are you so afraid of divide by 60? It is trivial as /6 /10 with
classical digital hardware chips. Or /3 /4 /5 depending on your outlook.

That is why the Babylonians so liked base 60!

The second hand is NOT stepping at 1 Hz, though; it\'s a synchronous electrostatic motor,
so there\'s no benefit to \'dividing down\' to one-per-second, rather one can just factor
any 2^N precursor of the one minute clock, and use a number of poles and
phases for the drive to accomplish the smooth sweep hand motion.

But they can divide down to 8Hz or 16Hz just as easily and that is more
than good enough to fool the human eye into seeing a continuous sweep
motion on the second hand. ISTR Rolex uses 8Hz on most of its watches.

They need two drives one at about 8+/-4Hz for the second sweep
synchronous motor and 1 pulse per minute for the second hand.

The latter can be trivially obtained from 1Hz using a divide by 60.

There is no need for a custom crystal for this. Unlike the situation for
a sidereal clock where making it run ~4 minutes a day faster than mean
solar time is way beyond the pull range of a crystal.

You can sort of fiddle it by dividing by 359 instead of 360 somewhere
(and indeed back in the day there were some telescopes with 359 teeth
main drive gear wheels intended to take a nominal 24h clock motor drive.

359 is annoyingly prime so I have no idea how they actually did this in
practice on a classic dividing engine but such gears do exist on
Victorian/Edwardian era observatory class telescopes 0.5m and bigger!

--
Martin Brown

 

[server]

On Tue, 13 Jun 2023 08:57:50 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

On Tuesday, June 13, 2023 at 12:00:39?AM UTC-4, Ricky wrote:
On Monday, June 12, 2023 at 10:57:26?PM UTC-4, whit3rd wrote:
In binary ripple counters, many bits change on a
clock tick (lowest bit changes every time, bit#2 changes half
the time, bit #3 changes every fourth clock...) so there\'s
a log(N) scaling for N-bit counters\' average bit-change cost.
The toggle rate ceiling in a binary counter is 2 per clock cycle. It\'s the series, 1 + 1/2 + 1/4 + ... asymptotically approaching 2.

That applies only on low voltage (<1.5 V) wrist watch ripple counters,
in which the output is effectively tri-state during each transition.
Energy is consumed only charging and discharging the output stray
capacitance. Even a very slow input transition doesn\'t cause extra
dissipation.

In high voltage (>3 V) CMOS both the N and P FETs are conducting
during the transition region, causing extra dissipation during each
state change. This also defines the maximum allowed input transition
times.

Yeah, I goofed; was thinking of 1/N sequence instead of 1/(2^N).
Internal decision-making for Gray count seems complex enough to
swamp any savings on the outputs, and pseudorandom sequences with
shift registers can be expected (because the internal logic is so simple)
to do better on silicon, simply because CCD-like chains can implement
the shift with near-zero energy input.

One would get the clock division-by-(2^M) from ripple counters, or synchronous,
but division-by-((2^M)-1) is the divisor for a maximal
pseudorandom sequence. There\'d be an M-wide gate to detect the count, but
only the one gate required. Clean output requires a clocked latch on that gate,
lest false triggers happen.

How would you implement the PRS shift register ? With some
(mercury/glass) acoustic delay line ?

If with flip-flops, each flip-flop would operate a full clock
frequency, consuming more power. For some number of stages a single
XOR gate is sufficient, but some other lengths 2 or 3 XOR gates are
required, each operating at full clock frequency.

Thus a ripple counter is preferable for low power dissipation

Generating a one-Hz second hand drive would work OK from a 32727 Hz quartz
crystal with pseudorandom division, rather than the more common 32728 Hz value.

 

[Jasen Betts]

On 2023-06-19, Martin Brown <\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

On 18/06/2023 22:01, whit3rd wrote:
On Sunday, June 18, 2023 at 1:25:15 PM UTC-7, Martin Brown wrote:
On 18/06/2023 03:18, whit3rd wrote:
On Saturday, June 17, 2023 at 11:26:09 AM UTC-7, Ricky wrote:
On Saturday, June 17, 2023 at 12:16:38 PM UTC-4, whit3rd wrote:

[about Accutron DNA watch]
The minute-hand \'tick\' is the slowest clock required for that watch (with minutes/hours
being gear-connected). A crystal with power-of-two division to minutes(rather than seconds)
would be expected; nearest to the common 32768 Hz would be 30720 Hz.
Digikey doesn\'t stock that particular value, though: it\'d be a custom rock.

Why are you so afraid of divide by 60? It is trivial as /6 /10 with
classical digital hardware chips. Or /3 /4 /5 depending on your outlook.

That is why the Babylonians so liked base 60!

The second hand is NOT stepping at 1 Hz, though; it\'s a synchronous electrostatic motor,
so there\'s no benefit to \'dividing down\' to one-per-second, rather one can just factor
any 2^N precursor of the one minute clock, and use a number of poles and
phases for the drive to accomplish the smooth sweep hand motion.

But they can divide down to 8Hz or 16Hz just as easily and that is more
than good enough to fool the human eye into seeing a continuous sweep
motion on the second hand. ISTR Rolex uses 8Hz on most of its watches.

They need two drives one at about 8+/-4Hz for the second sweep
synchronous motor and 1 pulse per minute for the second hand.

The latter can be trivially obtained from 1Hz using a divide by 60.

There is no need for a custom crystal for this. Unlike the situation for
a sidereal clock where making it run ~4 minutes a day faster than mean
solar time is way beyond the pull range of a crystal.

You can sort of fiddle it by dividing by 359 instead of 360 somewhere
(and indeed back in the day there were some telescopes with 359 teeth
main drive gear wheels intended to take a nominal 24h clock motor drive.

359 is annoyingly prime so I have no idea how they actually did this in
practice on a classic dividing engine but such gears do exist on
Victorian/Edwardian era observatory class telescopes 0.5m and bigger!

if you can\'t there by multiplying, add.
adding rotation can be done using differential gears.

--
Jasen.
🇺🇦 Слава Україні

 

[Joe Gwinn]

On Mon, 19 Jun 2023 10:08:02 +0100, Martin Brown
<\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

[snip]

You can sort of fiddle it by dividing by 359 instead of 360 somewhere
(and indeed back in the day there were some telescopes with 359 teeth
main drive gear wheels intended to take a nominal 24h clock motor drive.

359 is annoyingly prime so I have no idea how they actually did this in
practice on a classic dividing engine but such gears do exist on
Victorian/Edwardian era observatory class telescopes 0.5m and bigger!

On a very high precision dividing engine, they started at the setting
for 360 teeth on the circle, and then make the step length slightly
larger (so the circle didn\'t quite close after walking around the
circle, increasing the step size gradually until closure was again
achieved. A version of Newton\'s method was used to improve
convergence speed.

Joe Gwinn

 

[whit3rd]

On Monday, June 19, 2023 at 2:08:12 AM UTC-7, Martin Brown wrote:

On 18/06/2023 22:01, whit3rd wrote:
On Sunday, June 18, 2023 at 1:25:15 PM UTC-7, Martin Brown wrote:
On 18/06/2023 03:18, whit3rd wrote:
On Saturday, June 17, 2023 at 11:26:09 AM UTC-7, Ricky wrote:
On Saturday, June 17, 2023 at 12:16:38 PM UTC-4, whit3rd wrote:

[about Accutron DNA watch]
The minute-hand \'tick\' is the slowest clock required for that watch (with minutes/hours
being gear-connected). A crystal with power-of-two division to minutes(rather than seconds)
would be expected; nearest to the common 32768 Hz would be 30720 Hz..
Digikey doesn\'t stock that particular value, though: it\'d be a custom rock.

Why are you so afraid of divide by 60? It is trivial as /6 /10 with
classical digital hardware chips. Or /3 /4 /5 depending on your outlook.

That is why the Babylonians so liked base 60!

The second hand is NOT stepping at 1 Hz, though; it\'s a synchronous electrostatic motor,
so there\'s no benefit to \'dividing down\' to one-per-second, rather one can just factor
any 2^N precursor of the one minute clock, and use a number of poles and
phases for the drive to accomplish the smooth sweep hand motion.

But they can divide down to 8Hz or 16Hz just as easily and that is more
than good enough to fool the human eye into seeing a continuous sweep
motion on the second hand. ISTR Rolex uses 8Hz on most of its watches.

The point here, though, is that lower frequencies than 32 kHz are used to step the
minute hand, while the 60:1 ratio that drives the slower hour hand is done by gearing,
rather than electronically. The cascade of flipflops that eventually
creates the one minute pulse for minute-hand incremental movement includes
lots of faster-than-a-second values, which can drive multiple phases of subsecond
period. An N-phase clock delivers N pulses to move an M-pole rotor by 1/M of
a revolution, in a synchronous AC motor such as the electrostatic drive of the second hand.

Thus, to achieve 1.0 revolution of the second hand, in one minute, smoothly,
you want a frequency F that satisfies
1 minute= 60 s = M/(F/N)
where F would, most conveniently, be a power-of-two multiple of the one-per-minute pulse that drives
the minute hand. That implies that one can conveniently set M * N =2^(any small integer) to achieve
the speed one wants.

It\'s not clear that a clock division by 60 results in a useful divisor for minutes or seconds or hours.

There is no need for a custom crystal for this. Unlike the situation for
a sidereal clock where making it run ~4 minutes a day faster than mean
solar time is way beyond the pull range of a crystal.

The tuning-fork crystals are tuned by electroplating the tines and
then trimming off excess weight with a laser... it\'s trivial to change
the process and make a custom crystal. Old AT-cut disks were tuned by
grinding a batch of discs to thickness, and occasionally pulling one
out to test: if you ground too thin, the target frequency was lost for
the whole batch. Mass production for TV colorburst (3.57954 MHz)
crystals meant that faster rocks (4 MHz) were cheap; that\'s because a LOT
of batches were too thin to fix with heavier silver-plate electrode deposition.

So, I expect that a custom crystal is an economic thing for this purpose, today.

You can sort of fiddle it by dividing by 359 instead of 360 somewhere
(and indeed back in the day there were some telescopes with 359 teeth
main drive gear wheels intended to take a nominal 24h clock motor drive.

359 is annoyingly prime so I have no idea how they actually did this in
practice on a classic dividing engine but such gears do exist on
Victorian/Edwardian era observatory class telescopes 0.5m and bigger!

Still today, the 127-tooth gear for lathe threading purposes to match both
metric and inch standards is an annoying item.

Even nominally metric-only countries use BSP plumbing...

 

[whit3rd]

On Monday, June 19, 2023 at 12:03:12 AM UTC-7, Ricky wrote:

On Monday, June 19, 2023 at 2:41:21 AM UTC-4, whit3rd wrote:
On Sunday, June 18, 2023 at 11:03:50 PM UTC-7, Ricky wrote:
On Monday, June 19, 2023 at 12:45:39 AM UTC-4, whit3rd wrote:
On Sunday, June 18, 2023 at 9:36:03 PM UTC-7, Ricky wrote:
On Monday, June 19, 2023 at 12:21:23 AM UTC-4, whit3rd wrote:
On Sunday, June 18, 2023 at 8:47:48 PM UTC-7, Ricky wrote:

Uh, how do you count down without using flipflops?

Shift register, gates determine the inshifted bit... there\'s latched bits (flipflops, if you will)
but not \'toggle\' control of them. The pseudorandom sequence generated only goes
to all-ZERO outputs once per cycle, but cannot do all-ONE outputs without stalling.
So, it cannot do divide-by-2^N, but at most divide-by-((2^N) -1).

Sorry, I have no idea what you are trying to say about this. So they use FFs. Glad we have that clear. I\'m familiar with pseudo random sequences, but what advantage to they provide here?

....
> I have no idea what you are talking about. Sorry.

The point of a clocked timer is that it indicates when it has run a full many-clocks
sequence. Both an array of flipflops, and a pseudorandom sequence generator, take
many clocks to complete a sequence. Both are clocked, and can indicate a time at the
end of the sequence. The fact that \'pseuorandom sequence generator\' makes a
sequence is interesting, but it is NOT the only function that that particular kind of
hardware can serve. It also divides down a fast clock, if you note the occurrences of
repetition of its state.

 

[Ricky]

On Monday, June 19, 2023 at 1:52:11 PM UTC-4, whit3rd wrote:

On Monday, June 19, 2023 at 2:08:12 AM UTC-7, Martin Brown wrote:
On 18/06/2023 22:01, whit3rd wrote:
On Sunday, June 18, 2023 at 1:25:15 PM UTC-7, Martin Brown wrote:
On 18/06/2023 03:18, whit3rd wrote:
On Saturday, June 17, 2023 at 11:26:09 AM UTC-7, Ricky wrote:
On Saturday, June 17, 2023 at 12:16:38 PM UTC-4, whit3rd wrote:

[about Accutron DNA watch]
The minute-hand \'tick\' is the slowest clock required for that watch (with minutes/hours
being gear-connected). A crystal with power-of-two division to minutes(rather than seconds)
would be expected; nearest to the common 32768 Hz would be 30720 Hz.
Digikey doesn\'t stock that particular value, though: it\'d be a custom rock.

Why are you so afraid of divide by 60? It is trivial as /6 /10 with
classical digital hardware chips. Or /3 /4 /5 depending on your outlook.

That is why the Babylonians so liked base 60!

The second hand is NOT stepping at 1 Hz, though; it\'s a synchronous electrostatic motor,
so there\'s no benefit to \'dividing down\' to one-per-second, rather one can just factor
any 2^N precursor of the one minute clock, and use a number of poles and
phases for the drive to accomplish the smooth sweep hand motion.

But they can divide down to 8Hz or 16Hz just as easily and that is more
than good enough to fool the human eye into seeing a continuous sweep
motion on the second hand. ISTR Rolex uses 8Hz on most of its watches.
The point here, though, is that lower frequencies than 32 kHz are used to step the
minute hand, while the 60:1 ratio that drives the slower hour hand is done by gearing,
rather than electronically. The cascade of flipflops that eventually
creates the one minute pulse for minute-hand incremental movement includes
lots of faster-than-a-second values, which can drive multiple phases of subsecond
period. An N-phase clock delivers N pulses to move an M-pole rotor by 1/M of
a revolution, in a synchronous AC motor such as the electrostatic drive of the second hand.

Thus, to achieve 1.0 revolution of the second hand, in one minute, smoothly,
you want a frequency F that satisfies
1 minute= 60 s = M/(F/N)
where F would, most conveniently, be a power-of-two multiple

Why would a power of 2 be \"most\" convenient? I fail to see the significance. Dividing by any integer is trivial. Most effective is a loadable counter with a carry chain. When the counter reaches all 1s, the counter is loaded with the appropriate preset.

of the one-per-minute pulse that drives
the minute hand. That implies that one can conveniently set M * N =2^(any small integer) to achieve
the speed one wants.

Only if you are willing to work with an arbitrary F.


> It\'s not clear that a clock division by 60 results in a useful divisor for minutes or seconds or hours.

It\'s clear to me. What part do you not understand? Dividing 1 by 60 gives 1/60 which is the period of a minute. Is that not clear?

There is no need for a custom crystal for this. Unlike the situation for
a sidereal clock where making it run ~4 minutes a day faster than mean
solar time is way beyond the pull range of a crystal.
The tuning-fork crystals are tuned by electroplating the tines and
then trimming off excess weight with a laser... it\'s trivial to change
the process and make a custom crystal. Old AT-cut disks were tuned by
grinding a batch of discs to thickness, and occasionally pulling one
out to test: if you ground too thin, the target frequency was lost for
the whole batch. Mass production for TV colorburst (3.57954 MHz)
crystals meant that faster rocks (4 MHz) were cheap; that\'s because a LOT
of batches were too thin to fix with heavier silver-plate electrode deposition.

So, I expect that a custom crystal is an economic thing for this purpose, today.

I have no idea of the economics. You still have not told us what you are doing. So how can we know what the constraints are? Have you inquired about the cost off such a crystal? How many units will you be buying in a year?

You can sort of fiddle it by dividing by 359 instead of 360 somewhere
(and indeed back in the day there were some telescopes with 359 teeth
main drive gear wheels intended to take a nominal 24h clock motor drive..

359 is annoyingly prime so I have no idea how they actually did this in
practice on a classic dividing engine but such gears do exist on
Victorian/Edwardian era observatory class telescopes 0.5m and bigger!
Still today, the 127-tooth gear for lathe threading purposes to match both
metric and inch standards is an annoying item.

Even nominally metric-only countries use BSP plumbing...

Duh! One thing you don\'t want to mess with is plumbing.

--

Rick C.

-+-- Get 1,000 miles of free Supercharging
-+-- Tesla referral code - https://ts.la/richard11209