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[time-freq] Query: Interest in clock synthesizer module -- useful for stabilizing PC timekeeping (among other things)

Mark Miller markm at kramrellim.com
Sat Aug 19 13:46:47 UTC 2006


I would be interested in this kit as a replacement for my IC-746pro's 32 
MHz reference frequency.  It would be nice to be able to bring in a very 
precise and stable 10 MHz reference and have it converted to a 32 MHz clock 
for this rig.  I have another rig that uses a 30 MHz reference.

I very much like your idea of using it as the clock for a PC and sound 
card.  I have often wished for very stable and accurate sampling rates for 
sound cards.

Great idea.  I have no problem with a surface mount kit.


Mark N5RFX

At 03:49 PM 8/16/2006, you wrote:
>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 switches.
>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 rates.
>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.
>John Ackermann
>jra at febo.com
>time-freq mailing list
>time-freq at lists.tapr.org

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