[time-nuts] Happy Holidays

[Bruce Griffiths]

Richard H McCorkle wrote:
> Ho Ho Ho
>
> Merry Christmas from the far north to all the
> Time-Nuts. As a gift for the holidays I have
> created a free version of the PICTIC for you
> and Didier has kindly posted the files at:
>
> http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:pictic
>
>
> And to all a good night,
>
> Richard
>
>
>   
Richard

Your analog interpolator needs a little work.
The switching speed of the 2N3906's is so slow because the 2N3906's that
switch the current to ground or into the 470pF cap are saturated.
They will switch much faster if used as current mode switches.
In fact you can just replace the 2N3906 whose collector is connected to
the 470pF cap with a fast switching diode and the current source will be
switched much faster.
The 2N7000's have a relatively high non linear output capacitance
replacing them with something like 1/6X 74HC05 would be better.
The 470pF silver mica caps will have relatively large dielectric absorption.
NP0/C0G caps would be a better choice, particularly if higher input
pulse rates were to be used.

Have you actually measured the linearity of the interpolator?


Bruce