[time-nuts] GPSDO using 100Hz
Joseph M Gwinn
gwinn at raytheon.com
Tue Nov 25 20:38:10 UTC 2008
time-nuts-bounces at febo.com wrote on 11/24/2008 08:31:22 PM:
> Bruce wrote:
> > Analog time constants of several hours are generally considered
> > impractical due to the lack of suitable low noise components
> > principally high value resistors and capacitors.
> > So how do you propose to get around this with an analog control loop?
>
> Not too many years ago, high-impedance op-amps and teflon capacitors
> were the way to do this.
>
> The op-amp companies had application notes discussing
> "soakage"/dielectric
> absorption in these circuits.
One can buy 10 microfarad metallized polypropylene capacitors new for
about $20 each from Newark et al. The soakage of polypropylene is very
small.
Joe Gwinn
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