Bruce Griffiths Correction added:
> Said > > Not this particular implementation but have built similar circuits > decades ago. > Tempco isnt an issue. > There's plenty of time to interleave calibration cycles of say 100ns, > 200ns, 300ns, 400ns duration between PPS measurements. > It should even be possible to correct residual low order non linearity. > > With some elaboration is easy to construct a BJT current source with a > residual tempco of around _100 ppm/C_ or so due to the BJT's hfe (~100) > tempco. > Replacing the polystyrene cap with a C0G/NP0 cap is probably worthwhile > especially if one wishes to avoid hand soldering the polystyrene cap > using heat sinks on the cap leads. > > This technique and variants thereof have been in use for decades in > nuclear instrumentation. > Another widely used technique is the Wilkinson converter wher the > capacitor is charges by a large current during the time interval to be > measured and the discharge time with a current perhps 1/1000 of this is > measured using a comparator and a counter clocked at 10 or even a 100 MHz. > > Bruce > > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.