That same frequency 4.19304 MHz was used in the infamous Lockerbie
flight 103 bom b timer, the Swiss made MEBO MST-13. The design of that
timer was such that it could be optioned to be set up to hours.
Why I know this? I was reading the history of this the other day and
FBI's involvement
On 3/31/19 5:29 PM, Neville Michie wrote:
I have a Philips quartz clock that runs on 4.19 MHz.
In spite of the high frequency it still runs for years
on a C cell.
Can any of the quartz crystal gurus explain why this
frequency was chosen? I believe that this clock was
supposed to have better
Hi
Simple answer is that it likely is an AT cut crystal. You can get a 1 ppm-ish
sort of stability over
0 to 50 C out of an AT. The 32 KHz crystal you sort of expect to see likely has
a couple hundred
ppm-ish stability over the same temperature range.
32 KHz crystal have been the norm in
2 to the 22nd power is 4.194304MHz.
32768 Hz crystals are a tuning fork cut with a very different temperature
curve than a typical AT cut which your 4.19MHz crystal probably is.
Tim N3QE
On Sun, Mar 31, 2019 at 6:03 PM Neville Michie wrote:
> Hi,
> I have a Philips quartz clock that runs on
I forgot to add that there's nothing remarkable about 4.194304 MHz in
terms of stability - it's just high enough to fit in reasonably small
packaging for clock use, and not take too-too much power. Lower
frequencies can work just fine, but the crystal tends to get way bigger.
The 32,768 kHz
Neville Michie wrote:
Hi,
I have a Philips quartz clock that runs on 4.19 MHz.
In spite of the high frequency it still runs for years
on a C cell.
Can any of the quartz crystal gurus explain why this
frequency was chosen? I believe that this clock was
supposed to have better than usual accuracy.
Your crystal doesn't show enough digits to see why it's a common value.
The "exact" number should be 4.194304 MHz, which is 2^22. It can be
divided by this base-2 integer conveniently to make 1 Hz for clock use.
The crystal marking, especially on small, common parts is often rounded
or
Easy. 2^22 is 4194304. This means that a crystal of that frequency connected to
a chain of 22 flip-flops will produce one pulse per second. More modern Quartz
clocks are based on 32768Hz crystals which is 2^15Hz. The reason for the change
is that such low frequency crystals require a
In message , Neville Michie
writes:
>Can any of the quartz crystal gurus explain why this
>frequency was chosen?
2 to the 22nd power = 4194304 ?
--
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FreeBSD committer | BSD
Could it really be 4.194304 MHz (2^22 Hz)?
Dana
On Sun, Mar 31, 2019 at 5:03 PM Neville Michie wrote:
> Hi,
> I have a Philips quartz clock that runs on 4.19 MHz.
> In spite of the high frequency it still runs for years
> on a C cell.
> Can any of the quartz crystal gurus explain why this
>
Hi,
I have a Philips quartz clock that runs on 4.19 MHz.
In spite of the high frequency it still runs for years
on a C cell.
Can any of the quartz crystal gurus explain why this
frequency was chosen? I believe that this clock was
supposed to have better than usual accuracy.
Philips always had a
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