From: jeroen@nospam.please   
      
   On 1/7/26 22:38, TTman wrote:   
   > On 07/01/2026 17:53, john larkin wrote:   
   >> On Wed, 7 Jan 2026 15:41:04 +0000, TTman    
   >> wrote:   
   >>   
   >>> Bac in the early 80s, I nade a lot of money selling 'better than normal   
   >>> accuracy' digital watches. A colleague designed and made an accuracy   
   >>> tester that showed +/- 20 seconds/month. The source accuracy was from   
   >>> MSF Rugby RF transmitter ( 1 pulse/second?). The detector ( I think) was   
   >>> some form of piezo... it was about 2mm diameter glued into a BNC housing   
   >>> ( for simplicity). It worked by touching the piezo probe onto the back   
   >>> of the watch ( with the back off) and I was able to adjust the trim cap   
   >>> to get close to a few seconds per month ( ignore ambient/body temp)   
   >>> This probe went into the box via a cable, was amplified and somehow   
   >>> comaped to the source and converted into secs/month.   
   >>> Can anyone figure out how this probe was constructed?   
   >>> Reason- I want to build another one with a 10Mhz reference Xtal etc.   
   >>> any suggestions welcomed.   
   >>   
   >> I'd expect that removing the back affects the oscillator frequency.   
   >   
   > More than likely... but a re test after adjustment and the back replaced   
   > would cover that. Could what I thought was a 'piezo' at the end of the   
   > probe just have been a piece of wire?   
   >>   
   >>   
   >> John Larkin   
   >> Highland Tech Glen Canyon Design Center   
   >> Lunatic Fringe Electronics   
   >   
   >   
      
   I think the coupling was quite possibly acoustic rather than electric.   
      
   Jeroen Belleman   
      
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