[time-nuts] Setting Osc Frequencies

Dr Bruce Griffiths bruce.griffiths at xtra.co.nz
Sat Mar 3 22:52:40 EST 2007


Bill Janssen wrote:

  

> I built my own version of this scheme and it works OK but mine has some 
> "issues"
> So I would like to have at least three of these.to replace my one.
>
> Anyone willing to take on the job of designing a circuit board?
>
> I log my results with a A-D converter and my Basic program
>
> Bill K7NOM
>   
Bill

I can design a suitable circuit but may need someone else to do the 
layout as my PCB layout software is rather ancient.

There are several options.

1) A CMOS design that operates with input frequencies up to about 20MHz 
or so but is relatively inexpensive.

2) A modern  ECL design that will operate with input frequencies up to 
about 500MHz at a significantly greater cost.

3) A state of the art SiGe ECL design that will operate with input 
frequencies up to 1GHz or so. The components wont be much more expensive 
than option 2 but will probably need a PCB with a good high frequency 
dielectric (teflon etc).

I would suggest that option 1 would be perfectly adequate for comparing 
5 and 10MHz sources, whereas comparing 100MHz sources would require 
either option 2 or option 3. If anyone wants to compare 1GHz sources 
then option 3 would be useful.

Of course one can always use an external divider to produce frequencies 
within the input range of the comparator.

Bruce



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