[time-nuts] Ugly Frequency Dividers

[Jean-Louis Oneto]

Hello,
It's may be a little out of our direct concerns, but do you know this 
beautiful digital clepsydra:
http://www.marcdatabase.com/~lemur/dm-gitton.html

or its Javascript emulation:
http://www.time-flow-clock.de/

73,
Jean-Louis Oneto
e-mail: Jean-Louis.Oneto at obs-azur.fr


----- Original Message ----- 
From: "Normand Martel" <martelno at yahoo.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Friday, August 11, 2006 12:02 AM
Subject: Re: [time-nuts] Ugly Frequency Dividers


> This morning, i've just remembered another weird
> frequency divider i say on a chronorecorder (a device
> used to adjust mechanical watches) a few years ago...
>
> The frequency dividers stages (three or four, i'm not
> sure) were unijunction transistor based staircase
> generators using the charge pump/reservoir principle
> to divide the input frequency by an integer "N"
> factor. Interinstignly, the "N" factor was adjustable
> using a potentiometer.
>
> Again here, just as with the ring counter, no glitch
> problem here, as with the binary dividers, but the pot
> had to be carefully adjusted so it is in the middle of
> the correct "N" range, this way, the counter can
> resist  aging.
>
> Interinstignly, since it uses the charge
> pump/reservoir principle instead of the well hnown
> gated monostable, this counter is relativey (within a
> reasonable measure) frequency independant.
>
> Again, just as the all-transistor ring counter, i do
> not have the schematic, but i know the owner of the
> chronorecorder, and next time i'll see him, i'll ask
> for a look inside the device to sketch a schematic.
>
> BTW, i do not know the jitter response of such a
> counter, but i can eassilly imagine that it is very
> poor (slow transitions), but since it smells analog, i
> like it!! ;-)
>
> 73 de Normand VE2UM
> Montreal, Qc, anada
>
>
>
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