[time-nuts] Low temperature coefficient capacitors for DMTD

[Bruce Griffiths]

Corby Dawson wrote:
> The NBS DMTD uses a .15uf polycarbonate capacitor for the filter channel.
>
> The polycarbonate TC is a bit better than the PPS but they are hard to
> find for the "mini" DMTD at a decent cost.
>
> Most manufacturers no longer make polycarbonate capacitors.
>
> The substitution of the PPS capacitors into the 106D showed a very small
> improvement in performance over the existing polycarb.
>
> My suggestion of using the PPS capacitors was predicated on that .15uf
> value as I would not try to parallel enough NPO C0G to reach that value.
>
> As temperature swings in my lab over the time span of most plots is quite
> small the PPS seems the most cost effective.
>
> Corby
>    
0.1uF and 0.22uF NP0/C0G SMT caps are readily available, leaded versions 
are also availble.
Polycarbonate film production ceased about 10 years ago.

Bruce