Path: ...!weretis.net!feeder8.news.weretis.net!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: Michael Schwingen Newsgroups: sci.electronics.design Subject: Re: Cap C-V test Date: 4 May 2025 16:46:05 GMT Lines: 27 Message-ID: References: X-Trace: individual.net ivG7wiq0exNWzDfrSThROAwqGMvwZ5Rl/7aJD0VL/d2TAayeAN Cancel-Lock: sha1:DC2vpy1GfztJEdgGlK4wI/UPwBo= sha256:aOYmGOnMEpmpk2X3m2HRMGGwCvpgZgXX6exB+6uXXkQ= User-Agent: slrn/1.0.3 (Linux) Bytes: 1766 On 2025-05-04, john larkin wrote: >> >>Not really - according to your measurements, at 25V, the caps should have >>about 1.46uF, so the series combination has 0.73uF instead of the 0.83uF of >>the parallel combination. > > One cap is .83 at 50 volts. Two in parallel would be 1.66. > The series pair is about .73 as you note. That assumes that the DC > voltage divides equally. Upps, yes. Must have been lack of coffee. > Ceramic cap nonlinearity is weird. To get the most C, is it always > better to pick the cap with the highest nameplate capacitance? Not sure. In one case where I needed about 9uF at 12V DC, standard X5R/X7R 22uF/25V all came out at about 7.5uF, and 22uF/35V were not a bit better. IIRC, X7S performed much better. Murata Simsurfing has typical Capacitance/DC bias curves for all their parts. cu Michael -- Some people have no respect of age unless it is bottled.