Analogue clock circuits?

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Were analogue circuits ever used in Digital clocks ? (aka. transistors
instead of IC's). As far back as I can remember, even in the 80's,
Elementary Electronics magazine used a huge, many-pinned dedicated clock
chip for a clock project.
 Is this possible, or would it require literally hundreds of transistors?.
As a sidenote, my roommate in College in 79, had a "Digital Clock" that used
a complicated arrangement of motors, cams, and microswitches to illuminate
light bulbs in 7 segment displays. It was incredibly complicated, and well
thought out, but was probably one of the few "Digital"  clocks that hummed
and clicked while it ran.

Kim

"A Man Of  True Frankensteinian Proportions"



Re: Analogue clock circuits?


Talking electronics did a digital clock in the 80's that used a bunch of
counter IC's and some transistor logic. keeps 100% perfect time to this day
(gets it's clock off the mains 50 Hz).

This is about the minimum practical integration level for a hobbyist
project, without blowing out the cost to a crazy figure.


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Re: Analogue clock circuits?



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Where about are you? My 50Hz strays out and doesn't end up exactally. Over
time my 50Hz clocks end up almost 7 seconds per day off atomic clock via
internet.



Re: Analogue clock circuits?



"Dand"

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**  Bullshit.

The 50 Hz frequency is VERY accurate.

7 seconds per day loss can only happen if you have power outages.

Where are YOU ?

Back 'a Bourke ?



..........  Phil



Re: Analogue clock circuits?


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A heavily loaded alternator goes low in frequency, I've repaired a few
TTL based logic boards for the local power authority that trigger load
shedding at substations when the frequency goes a few tenths of a Hz
below 50 Hz. One tenth of a Hz over a day is nearly 3 minutes, in this
day and age of privatised power generation and poor investment in new
power stations for base load I would expect the frequency to drop in
the middle of summer.

Re: Analogue clock circuits?


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While the 50Hz varies up and down during the day, due to load
fluctuations, provided there are no power outages which result in loss
of synchronization, the average frequency for the day is 50Hz exactly.
This is why mains clocks maintain long term accuracy. During the day
however they can be a few seconds out either way.

Most 50Hz clocks which run fast have poor filtering, which results in
noise being counted as extra cycles, which cause them to run fast.

David

Re: Analogue clock circuits?


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I spoke with someone at enegex and they said 50Hz strays with the load by
+/-0.1Hz. He says the alternators have rotation counts each day and are
almost never the same.



Re: Analogue clock circuits?



"Dand"
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**  The frequency never really changes, the phase merely drifts up and down
around the centre value.

That is - on a high res frequency meter, the effective AC supply frequency
varies from say  50.1 to  49.9 over a couple of  minutes then drifts back
again.


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** All the alternators right across the Eastern half of Australia are phase
locked when in use.

 But they can stop and start when taken off line.

 So the rev count proves nothing.




.........  Phil






Re: Analogue clock circuits?


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No, the frequency of the mains does change, as the generators speed up
and slow down in response to the changing load. If a big load is
suddenly applied the frequency will drop until the control system on the
turbine compensates, and increases the power to turbine to increase the
frequency.

In a AC power system the only energy storage you have is the spinning
mass of the turbine/generator. If the load is too high the generator
will slow down, and if the load is too light, the generator will speed
up until the control circuit compensates. The problem with large base
load power stations is that for thermal reasons they can not change
there power instantly. They can only ramp up / down at a specified rate,
and can take several hours to ramp from half to full load.

On the other hand gas turbine and hydro don't have the thermal
constraints of a large coal fired station, and can supply the peak loads
more quickly.


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It can fall well below 49.9 for several minutes if there is a problem
with an alternator. In Tasmania where the grid is much smaller, the
frequency deviations are even greater, and it not uncommon to fall to
49.5 or less for several minutes, but they still maintain an average of
50.000 Hz

The standards require accumulated time deviation be within +/- 5 seconds
on the east coast, and +/- 15 seconds on Tasmania.

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The phase angle of each generator varies depending on its contribution
and distance to the load. It is important for power system stability
that the phase angle from one end of the power grid to the other does
not exceed 180 degrees.

David

Re: Analogue clock circuits?



"David"
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 **   Crapology.

  The  up / down phase drift is a complex function of load and control
inputs.



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 **  Not one -  but as large number of them in unison.


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 **  You would die waiting to see that happen.


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 **  But the rpm does not.

    So  "phase lock"  is the case.



..........   Phil





Re: Analogue clock circuits?


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You obviously have no experience in power systems. The frequency of the
mains can and does vary.

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Five events in August 2005 alone

22:00 hrs 14 August Loy Yang A unit 2 tripped from 530 MW
Min Freq = 49.810 Hz, below 49.85 for 338 seconds

22:00 hrs 17 August Loy Yang A unit 4 tripped from 310 MW
Min Freq = 49.835 Hz, below 49.85 for 20 seconds

20:29 hrs 20 August Eraring unit 4 tripped from 660 MW
Min Freq 49.740 Hz, below 49.85 Hz for  458 seconds

06:08 hrs on 24 August No contingency or load event
Min Freq 49.844 Hz, below 49.85 Hz for 18 seconds

10:26 hrs on 30 August Loy Yang A unit 2 tripped from 458 MW
Min Freq 49.828 Hz, below 49.85 Hz for 36 seconds


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No, it not a "phase lock", as the phase between the alternators is not
locked, and does not have a fixed relationship. The phase between the
alternators does vary depending on the load.


David

Re: Analogue clock circuits?



"David"
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 **  The mains supply is in every premises.

      Never noticed that  -  FUCKWIT  ??



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     **   ???????


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 **  ROTFL

Shame how not even ONE of them meets the meaning of "well below".

( snip pedantic shite )


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** You cannot read -  you sickening autistic prick.

  Phase locked   =  no change in rpm between units.





........  Phil






Re: Analogue clock circuits?


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No, the big generators at the power stations, and the big power lines
than connect them. Still, I remember studying them in third and fourth
year at university, something I believe that you missed out on.

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Please explain what YOU mean by well below? I know you snipped them
because you can't stand being wrong, but I would 49.74 Hz well below
49.9Hz in the context of power system frequency control, and it stayed
below 49.85 for 458 seconds.

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No, Phase Locked = no change in the PHASE ANGLE between the units. As
there is a change in phase between alternators depending on the load,
they are not phase locked. Again, something you might have learned about
if you finished studying.


David




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"David"
 Phil Allison:
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 **  You completely missed the point  -  fuckwit.


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** It was your phrase and you did   * NOT *  specify the meaning.

Engineers ought to be careful of hopelessly vague language when speaking to
folk outside their special areas.


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 **  No  "phase locked"    =  no change in rpm between units.

     Care to waltz




........  Phil





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You really don't have a clue do you?.

Re: Analogue clock circuits?



"Mark Harriss"

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** You really don't have a brain  - do you Mark ?

It got fried while you were down some  hole full of muddy water with a 240
volt powered hot air gun doing cable repairs for Telstra.


BTW

The Turneroid needs someone to bloat his flagging ego.

Time for you to do some more usenet cock sucking.




.......  Phil



Re: Analogue clock circuits?


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Most power up my end of the state has to be fed into a local Hydro
station to be "Cleaned up"  I don't how this is done but I suspect
they might run one alternator as a motor and pump water back to the
top of the dam to run back through the other turbine and alternator.

A guy I know who has a power station ticket tells me that in the 70's
and 80's their reputation depended on keeping the frequency accurate
through the day in sync with the reference chronometer. These days
the alternators are run at their limits to try and keep up with
modern electrical household loads so they run slower.

Re: Analogue clock circuits?


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mechanical or electronic? someone said that electronic clocks can be fooled
by glitches, something which could be cured with a decent filter....

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The guys that run the national grid will run it fast when the load lightens
to compensate.

~20 years ago I was in the cooontrol room at Benmore Hydro station (NZ's
biggest at that time, I think still the biggest one on the grid) they had
two clocks one was synchronised to an atomic standard (WWVH?) the other ran
from the mains. I think at the time I saw it the discrepancy was two seconds

Bye.
   Jasen

Re: Analogue clock circuits?


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Then you have a problem.
The 50Hz is extremely accurate.
My 50Hz mains clock (with 1/10sec display) does not loose 7 seconds in
a year, let alone a day. It is by far the most accurate clock I have
and have never had to reset it, except when the power fails. It is
under 1sec / year accurate.

Dave :)


Re: Analogue clock circuits?


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Sounds like a nixie tube clock - had one myself quite some time back, and a
friend had a frequency counter with them. Watching the nixies flash all over
the place keeping up with an input waveform was fun. :-) There's too many
transistors involved to make that a viable method (doable, but why?) - clock
IC's were about the first to come out once dedicated IC's became common in
the late 70's.

Cheers.

Ken



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