[Amps] ripple in B+ supply.

Gary Schafer garyschafer at comcast.net
Sat Mar 27 19:26:25 PDT 2010


Quote from the 2008 ARRL handbook power supply section:
"percent ripple is the ratio of RMS value of the ripple to the dc value in
terms of percentage".

As RMS does the same amount of work as dc does it would make sense to use
RMS as a comparison.

73
Gary  K4FMX

> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com]
> On Behalf Of Alex Eban
> Sent: Saturday, March 27, 2010 6:50 AM
> To: dezrat1242 at yahoo.com; amps at contesting.com
> Subject: Re: [Amps] ripple in B+ supply.
> 
> Since you cope with DC voltages, it makes sense to employ something
> close
> for the ripple and that average voltage. Fortunately, for the triangular
> wave form, the average is 1-3 of the peak to peak and it usually
> expressed
> as a percentage of the DC output value. RMS has nothing whatsoever to do
> with it. It was the method used by power supply designer for years.
> Alex		4Z5KS
> 
> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com]
> On
> Behalf Of Bill, W6WRT
> Sent: Thursday, March 25, 2010 7:15 PM
> To: amps at contesting.com
> Subject: Re: [Amps] ripple in B+ supply.
> 
> ORIGINAL MESSAGE:
> 
> On Thu, 25 Mar 2010 06:03:37 -0700, "Jim Thomson" <Jim.thom at telus.net>
> wrote:
> 
> >##  Bill, EVERY  arrl  book I have, [back to 1960] plus Orrs'
> >books  always references  ripple to RMS.   Every ARRL formulae
> >is referenced to RMS.
> 
> REPLY:
> 
> RMS is a useful piece of info, no argument there, but anyone who is
> seriously evaluating a PS will want to look at the output with a scope
> to
> see if there are any "funnies" going on such as the presence of
> excessive
> RF, missing or seriously unequal half-cycles from an FWB, etc.
> 
> Like I said, I am probably prejudiced. I was brought up in electronics
> by
> folks who taught me that a scope is more useful than a meter, and I
> still
> believe that. Of course it is best to have both, but in cases involving
> AC
> measurements, I reach for the scope first.
> 
> I worked at Tektronix for ten years too. No doubt that had some impact.
> :-)
> 
> 73, Bill W6WRT
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