[time-nuts] Setting Osc Frequencies

[Dr Bruce Griffiths]

Hal Murray wrote:
>> I can design a suitable circuit but may need someone else to do the
>> layout as my PCB layout software is rather ancient. 
>>     
>
> I'll be willing to turn the crank on the board layout as long as a few people 
> are willing to double check whatever I do.  (and nobody is in a hurry)
>
> I've been happy with PCB Express.
>   http://pcbexpress.com/
> $125 for 10 boards up to 9 sq inches, two layers, no solder mask or silk 
> screen.
> $265 with solder mask and silk screen.
>
>
>   
Hal

What file format can you accept for schematics?
I can produce Protel for Windows schematic files or Protel for DOS 
schematic files.

One thing to remember about the circuit is that it will exhibit 
nonlinearity at the each end of the range.
This is due to the minimum pulse width the logic (XOR gate) will produce 
(about 3ns or so for 74LCX and similar logic, 1.5ns for the original HP 
version, 400 psec for modern ECL).

Other than using the fastest logic possible the simplest way to 
circumvent this limitation is to use 2 such circuits (with the one of 
the clocks inverted in the second circuit.) and sort out which output to 
use in software when analysing the data.

The best way to implement this is to just build the extra output into 
the circuit, as it only requires a few extra flipflops and another 
inexpensive opamp.

Bruce