OK, note taken. Usually large capacitors are not available with tantalum dielectric, it seems that the last is a 1000uF 6.3V.
On Fri, Jan 6, 2012 at 6:54 PM, Bob Camp <li...@rtty.us> wrote: > Hi > > Oddly enough, if you use a tantalum electrolytic as C2, it's not very happy > in that circuit. Their leakage with low voltages on them can be pretty > nasty. > > Bob > > -----Original Message----- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf Of Poul-Henning Kamp > Sent: Thursday, January 05, 2012 5:50 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Thunderbolt? (re simple gpsdo.) >> capacitors > > In message > <CAL8XPmO76XuTETZC=33_v2YWuJGcw8gCvtTDHyae6E4MFb18=g...@mail.gmail.com> > , Azelio Boriani writes: > > >I have googled extensively trying to find something about the dual > >capacitor method of reducing the leakage current... nothing found. Please, > >can you indicate anything for me to learn more? > > It is very simple: > > R1 charges C1 to the DC potential and therefore C2 sees > (almost) no DC voltage, which means (almost) no leakage > current. C2 is still a capacitor for any AC or dV component. > > I belive I picked this trick up from a datasheet or app-note relating > to precision voltage references. > > Poul-Henning > > >> [Some op-amp] >-+-----R2-----+--> > >> | | > >> | ----- C2 > >> | ----- > >> | ____ | > >> +---|____|---+ > >> R1 | > >> | > >> ----- C1 > >> ----- > >> | > >> GND > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > p...@freebsd.org | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > > _______________________________________________ > 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. > _______________________________________________ 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.