[time-nuts] Frequency subtraction with D-flip flops

EWKehren at aol.com EWKehren at aol.com
Tue Jun 25 08:36:50 EDT 2013


Forty years ago I did a digital mixer using three J K FF's to subtract the  
IF from the LO for remote monitoring of radio stations. The output is not  
symmetrical but great for a frequency counter. Shortly there after Motorola  
introduced the MC12000 a D FF intended and widely used for PLL 
applications, I  have used it many times. More recently we are using two D FF's for  
mixing in A/V applications and very high resolution frequency measurements with 
 up to 1 E-15 a second using output frequencies from .5 Hz to 100 Hz.
Do to attachment limitations if you want more info contact me off list and  
I send you some scans.
Bert Kehren


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