Order Tray | Contact Us | Home | SIG Lists

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

Phil Theis phil at k3tuf.com
Wed Aug 16 21:03:52 UTC 2006

I believe I'd be interested in an under 50 kit.
Phil K3TUF 

-----Original Message-----
From: time-freq-bounces at lists.tapr.org
[mailto:time-freq-bounces at lists.tapr.org] On Behalf Of John Ackermann N8UR
Sent: Wednesday, August 16, 2006 4:49 PM
To: timekeepers at fortytwo.ch; Discussion of precise time and frequency
measurement; TAPR time and frequency projects; questions at lists.ntp.isc.org;
tacgps at lists.tapr.org
Subject: [time-freq] Query: Interest in clock synthesizer module -- useful
for stabilizing PC timekeeping (among other things)

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

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

More information about the time-freq mailing list