Thanks. Now it makes sense. Sorry for the interruption.
Joe -----Original Message----- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Azelio Boriani Sent: Saturday, June 15, 2013 4:58 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] HP and other equipment failure Although off-topic here, the PFC (or power factor correction) is a switching mode front-end used to correct the cos-phi of the otherwise capacitive load that every switching mode power supply is for the mains. On Sat, Jun 15, 2013 at 11:52 PM, J. L. Trantham <jlt...@att.net> wrote: > Sorry for the interruption but what is 'PFC'? > > Thanks. > > Joe > > -----Original Message----- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] > On Behalf Of Poul-Henning Kamp > Sent: Saturday, June 15, 2013 4:09 PM > To: Robert Atkinson; Discussion of precise time and frequency > measurement > Cc: Perry Sandeen > Subject: Re: [time-nuts] HP and other equipment failure > > In message > <1371329221.83869.yahoomail...@web171902.mail.ir2.yahoo.com>, > Robert Atkinson writes: > >> While I agree with everything else you say, you CAN have too much >> filter capacitance. At least where dc rectifier / filter (smoothing) >> circuits are concerned. Increasing C causes increased ripple current >> [...] > > And ripple current can be a major source of power-line frequency noise > in all electronics. > > The main reason why switchmode power-supplies today (can) outperform > linear power supplies with respect to noise, is because the legally > mandated PFC correction eliminates the bridge-rectifier ripple harmonics. > > I would not hessitate to use a good quality switchmode to replace the > linear supply in a HP5370B. > > I did some experiments a couple of years ago, with an audio-amplifier: > I put a standard PFC corrector chip on the secondary side of the trafo. > > The overall result was not satisfactory, but the 50 Hz "sneer" > we all know and hate was absent, and the "Tzoing!!!!!" power-on > mechanical shock from the trafo was also eliminated, as was the > consequent dimming of the lights ;-) > > The main reason not to do this, is that you need some physically > gargantuan coils for a 10A+ PFC-switcher. > > > -- > 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. _______________________________________________ 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.