[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.


John Ackermann
jra at febo.com

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