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   Message 142,004 of 143,102   
   john larkin to All   
   Re: Digital LCD watch accuracy tester   
   07 Jan 26 09:53:49   
   
   From: jl@glen--canyon.com   
      
   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.   
      
      
   John Larkin   
   Highland Tech Glen Canyon Design Center   
   Lunatic Fringe Electronics   
      
   --- SoupGate-DOS v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

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