Yep, injection locling works just fine
Don
- Original Message -
From: "paul swed"
To: "Discussion of precise time and frequency measurement"
Sent: Sunday, August 08, 2010 7:37 PM
Subject: Re: [time-nuts] Regulating a pendulum clock
Now I will get myself in a lot of trouble.
Why wo
Nice!
Don
- Original Message -
From: "Jim Palfreyman"
To: "Discussion of precise time and frequency measurement"
Sent: Sunday, August 08, 2010 6:12 PM
Subject: Re: [time-nuts] Regulating a pendulum clock (Jim Palfreyman)
Well last night I did a quick and dirty.
I got my (GPS lock
Oh, well, I have some 15 v baxck-to-back zeners extremely fast to help the
fuse out. In any case, the max current is limited by the power supply
Something can be worked out...
12 v actually limits the current through the coil(s) and heating even at
full on will not destroy anything. I'd probabl
Now I will get myself in a lot of trouble.
Why wouldn't a constant pulse at a 2 sec interval essentially lock the
pendulum after a bit.
If the pulse is always there and occurs just after the mid swing. I suspect
you do need to adjust current with a pot to get things settled. But
essentially open lo
Well last night I did a quick and dirty.
I got my (GPS locked) 3325B to generate square waves (0-5V) at 1 Hz. 500ms
on. 500ms off. I ran this through a relay that delivered 10mA at 25V to the
coil.
By adjusting the phase of the 3325B I got the ON to occur as the magnets
approached. But I had no i
Mere fast blow fuses aren't usually precise enough to protect
transistors against over current unless one uses rather large transistors.
Overcurrent protected drivers are available and readily designed/built.
Protection against di/dt transients due to external events is also
advisable.
Minimis
fast blow fuse, resonate the coil to the pwm frequency. Parts count small,
tinkering in software instead of breathing lead fumes or whatever noxious
stuff the Europeans have forced us to use...
Don
Bruce Griffiths
> No protection against external shorts or other undesired events.
> Extensive analo
No protection against external shorts or other undesired events.
Extensive analog filtering to avoid creating an effective radiator of
noise may also be necessary.
Simple analog techniques are probably simpler/cheaper once the necessary
filtering and protection are included.
Bruce
Don Latham
Hmmm lemme see. I think I'd use a 12 volt supply and two transistors
driven by two outputs on my Arduino,basic stamp,picaxe or other whizzie.
I'd then implement a PID controller essentially using the 1 sec pulse from
the pendulum and the 1 sec pulse from my Rb, satellite receiver, crystal
clock, or
In message <20100808230143.2285e822.att...@kinali.ch>, Attila Kinali writes:
>What surprises me though is the stability of the crystal.
>In the months between reboots, there is less than +-1ppm variation,
>The machine is a 16y old DEC PC, which has been used as a desktop
DEC used way better crys
J. Forster wrote:
You are picking very unimportant nits.
If there were a small noise spike from the opamp, it'd goose the pendulum
a tiny amount. That would be corrected on the next swing.
Heuristic analysis of this type is counter productive.
You are turning a trip to the corner store into
I have 25 pieces of the 74AC175PC on order from Arrow. $11.45 for 25 chips and
$9.98 to ship them here. If you want one let me know.
Dan Schultz N8FGV
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Moin,
I just had a little bit too much time at hand and had a look at
the ntp loopstats of one of my machine. Specifically at the ppm value.
After filtering out all items, where the ntp loop isnt running with
a poll intervall of 2^10, i got a more or less nice curve (see ntp.png).
The noise seen
That's why I suggested killing the BW of the opamps in the partial H
bridge configuration previously suggested. Transient response is almost
unneeded.
-John
==
> On 08/08/2010, mike cook wrote:
>> Check out Bryan Mumfords page.
>> http://www.bmumford.com/clocks/em2/index.html
>
> I
You are picking very unimportant nits.
If there were a small noise spike from the opamp, it'd goose the pendulum
a tiny amount. That would be corrected on the next swing.
You are turning a trip to the corner store into an Apollo Moon Mission.
BTW, since the =drive does not to be bipolar, one of
The LH0032, LH0033 and LH0063 come to mind again. - Regards - Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ 07731
732-886-5960
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Bruce Griffiths
Sent: Saturday, August 07, 2010 10:2
I real purist would adjust the pendulum moment-of-inertia, rather than drive
it.
If I ever get around to it, I will attach a long tube of mercury (or cesium)
to my pendulum and use heat to adjust the column height. A slightly less
elegant solution would use a stepping motor to adjust the locat
Hi all,
I think at this point I need to explain the electromagnet positioning.
The permanent magnet is on the rod about 25cm down (out of 100cm). The
electromagnet is on the left side and so gets close to the permanent
magnet every two seconds.
Injection locking would be a simple solution and wo
On 08/08/2010, mike cook wrote:
> Check out Bryan Mumfords page.
> http://www.bmumford.com/clocks/em2/index.html
I did not want to kick the pendulum with a pulse each swing as the
drive would be part and parcel of the existing clock mechanism. What I
was interested in was Don Mimlitch's descripti
According to www.octopart.com, Arrow Electronics has 1300 pieces of the
74AC175PC 16 pin PDIP in stock.
Dan Schultz N8FGV
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The attached single ended inverting driver is perhaps a better choice as
it allows a dc coupled noniverting amplifier with gain and significant
offset and drift to be substituted for the LT1010 buffer depicted if the
frequency compensation is adjusted to suit.
The series RC across the coil damps
Check out Bryan Mumfords page.
http://www.bmumford.com/clocks/em2/index.html
Le 08/08/2010 11:14, Steve Rooke a écrit :
I was rather more thinking of the setup that Don was suggesting as not
many domestic clocks have a seconds pendulum and it would otherwise
take dividing down a referenced osc
Hello,
As some of you know I have purchased a Palisade Smart Antenna of a
member of this group.
I was just wondering if anyone has a firmware upgrade for it, or can
tell me if I can upgrade the Firmware on it?
I am currently running 7.10.. all the NTP information about this device
mentions 7.12
I was rather more thinking of the setup that Don was suggesting as not
many domestic clocks have a seconds pendulum and it would otherwise
take dividing down a referenced oscillator to the correct frequency.
Cheers,
Steve
On 08/08/2010, Neville Michie wrote:
> Not many clocks are set up with the
Not many clocks are set up with the gear to modulate the rate,
but they are all still sensitive to injection locking.
A tiny rare earth magnet on the pendulum (say 1/2 way down the
pendulum rod)
and a coil fed with a stretched (say 250ms long) PPS or for a seconds
pendulum
PP2S pulse will pull
On 08/08/2010, Matt Osborn wrote:
> On Sun, 8 Aug 2010 02:38:53 +1200, Steve Rooke
> wrote:
>
>>Well, that does make a lot of sense, it's just a pity that searching
>>for the item you want frequently ends up fruitless but I agree that if
>>you search for anything, your sure to find it.
>
> Senior
Sorry for double post, modem dropped during sending and a refresh on
the browser when it was up resent the message.
Steve
On 08/08/2010, Steve Rooke wrote:
> This is very interesting and I wonder if the capabilities of this
> system being applied to any clock pendulum. If this sort of control
>
This is very interesting and I wonder if the capabilities of this
system being applied to any clock pendulum. If this sort of control
any pendulum, then I wonder if it's possible to sync it to some
standard.
Steve
On 08/08/2010, Don Mimlitch wrote:
> Jim Said:
>>It also has a coil mounted near t
This is very interesting and I wonder if the capabilities of this
system being applied to any clock pendulum. If this sort of control
any pendulum, then I wonder if it's possible to sync it to some
standard.
Steve
On 08/08/2010, Don Mimlitch wrote:
> Jim Said:
>>It also has a coil mounted near t
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