Hi The circuit I described, is (as stated) quiet down to 100 Hz. It's 3 db bandwidth is well below 10 Hz with the 47 uF cap. If you need it quiet down to 10 Hz or 0.000000001 Hz, you will need to buy a few more caps. It's still not rocket science.
For most OCXO or atomic standard testing applications out there, 10 Hz is low enough. Bob On Jan 31, 2013, at 9:41 PM, Charles P. Steinmetz <charles_steinm...@lavabit.com> wrote: > Bob wrote: > >> An AD 797, a couple of metal film resistors, and a fairly large (say 47 uf) >> plastic cap work pretty well. > > The band from 10 Hz down to 0.1 or 0.01 Hz is generally important when > testing oscillators. To keep the 797 input noise density below a few nV per > root Hz, the terminations must have very low resistance. With such low > resistance, a 47 uF cap won't even get you to 10 Hz, much less 0.1 or 0.01 Hz. > > One more thought: Many oscillators have internal regulators that are not > nearly as good as what you can build. No sense using an external supply with > 5 nV per root Hz noise density if it will be re-regulated inside the > oscillator by a circuit that has a noise density of 250 nV per root Hz. > > Best regards, > > Charles > > > > > _______________________________________________ > 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. _______________________________________________ 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.