[ntp:questions] Query: Interest in clock synthesizer module -- useful for stabilizing PC timekeeping (among other things)
John Ackermann N8UR
jra at febo.com
Wed Aug 16 20:49:22 UTC 2006
I'm working on a project for TAPR (http://www.tapr.org) that might be of
interest to the timekeeping community.
It's a very simple clock synthesizer called the "Clock-Block" that
accepts a reference input in the roughly 2-50MHz range and generates an
output in the 5-250MHz range, programmable by a series of jumpers or
My primary inspiration for designing this circuit was Poul-Henning
Kemp's suggestion that it would work nicely to replace the crystal
oscillator on a PC to allow much more stable timekeeping. For example,
it can generate 14.318182MHz or 33.333333MHz from a GPS disciplined
oscillator or other stable reference. A PC with a Clock-Block and
external reference should be able to keep *very* good NTP time.
But there are likely to be other interesting uses as well; one I'm
considering is replacing the clock in a sound card to get precise sample
There's information about my prototype (and a picture) at
The prototype works well and we are now ready to move to production.
Before we do that, I'd like to get a sense of the interest level (if
any), and in particular whether there's enough demand to warrant an
semi-kit or assembled version instead of TAPR's usual bag o' parts.
As a kit, the Clock-Block would be quite inexpensive; we haven't
finalized the BOM yet but I believe TAPR would be able to sell it for
well under $50.
However, assembly may be problematic for some folks, because the
synthesizer chip is a "SSOP" surface mount package with about 0.5mm lead
pitch. I've had no trouble putting down these chips using a microscope
and small iron but not everyone may be willing to take on that challenge.
I am guessing that given the likely low volume, a semi-kit (all the
surface mount parts soldered down, but the remaining parts -- two DIP
switches and four 2 pin headers -- left as an exercise for the buyer,
would cost in the range of $80-$100.
A fully assembled and tested version would probably be $100-120 (most of
the increased cost is testing, not soldering down the few remaining parts).
I've tried to be conservative in these prices and I hope the actual
price will be lower, but don't know that for sure at this point. A lot
depends on quantity so there's a bit of chicken and egg here.
I'm hoping to collect no-obligation expressions of interest from this
group, assuming prices in the ranges described above. If you'd be
interested in buying one or more Clock-Blocks, please let me know
privately how many, and what version.
jra at febo.com
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