[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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