[ntp:questions] Re: Query: Interest in clock synthesizer module -- useful for stabilizing PC timekeeping (among other things)
Richard B. Gilbert
rgilbert88 at comcast.net
Wed Aug 16 22:41:17 UTC 2006
John Ackermann N8UR 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
> 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.
> John Ackermann
> jra at febo.com
> questions mailing list
> questions at lists.ntp.isc.org
I think the big issue here would be replacing the PC's native hardware.
It would void the warranty (at the very least).
It would have to be removed before anyone would attempt any required
repairs, etc, etc.
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