On Wed, 08 May 2013 21:52:21 -0700, John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:> >>>George did it! >> >>And unlike you he stood up and admitted it. >> >>?-) > >Got anything interesting to say about capacitors? >You are very reactive, just like a good capacitor. ?-)
Crapacitors
Started by ●May 2, 2013
Reply by ●May 10, 20132013-05-10
Reply by ●May 10, 20132013-05-10
On Fri, 10 May 2013 18:31:22 -0700, josephkk <joseph_barrett@sbcglobal.net> wrote:>On Wed, 08 May 2013 21:52:21 -0700, John Larkin ><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: > >> >>>>George did it! >>> >>>And unlike you he stood up and admitted it. >>> >>>?-) >> >>Got anything interesting to say about capacitors? >> >You are very reactive, just like a good capacitor. > >?-)I'll take that for a "no." -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Reply by ●May 17, 20132013-05-17
On Thu, 09 May 2013 09:22:02 -0700, John Larkin wrote:> Good c-meters apply a small ac voltage, millivolts, and measure the small > resulting ac current. They put DC bias on top of that.Better C meters have variable ac voltage. -- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)
Reply by ●May 17, 20132013-05-17
On Mon, 06 May 2013 22:25:06 -0700, John Larkin wrote:> Does anybody have an LT Spice script that includes the sort of grossly > nonlinear cap that we've been discussing here?Modeling nonlinear capacitors is fairly trivial. I know of several ways of doing it. Most are irritatingly slow. However, they don't adequately model the behavior of a Y5V ceramic. I did some detailed measurements recently. Small signal AC capacitance versus DC bias can be accurately modeled with a 5th order polynomial. However, stored charge versus applied DC, measured with an electrometer, follows a totally different curve, almost linear, nearly the nominal capacitance. Put another way, we have a "slow" capacitance, and a "fast" one, which are quite different. I need to investigate C versus f, next. LTspice's nonlinear capacitance model (Q=f(V)) doesn't appear to work with polynomials, at least in .ac analyses BTW. Pspice capacitance model has quadratic voltage coefficients, which LTspice barfs at. -- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)
Reply by ●May 18, 20132013-05-18
On Tue, 07 May 2013 08:45:54 +0200, Jeroen Belleman = <jeroen@nospam.please> wrote:>On 2013-05-07 06:39, josephkk wrote: >> On Fri, 03 May 2013 23:40:10 +0200, Jeroen <jeroen@nospam.please> =wrote:>> >>> On 2013-05-03 23:23, dagmargoodboat@yahoo.com wrote: >>>> On May 3, 3:39 pm, John Larkin <jlar...@highlandtechnology.com> =wrote:>>>>> On Fri, 3 May 2013 07:30:44 -0700 (PDT), dagmargoodb...@yahoo.com >>>>> wrote: >>>>> I did manage to sumulate a frequency divider of sorts, really a >>>>> subcycle parametric oscillator, based on the C:V curve of a diode. =It>>>>> should work with a ceramic cap, too. But it's still pumped, not >>>>> self-oscillating. >>>>> >>>>> =https://dl.dropboxusercontent.com/u/53724080/Circuits/Oscillators/Sub...>>>>> >>>>> This is a classic diode frequency multiplier, but it halves the >>>>> frequency instead of doubling it. Conversion efficiency is >>>>> impressively bad. >>>> >>>> Yes, very impressively bad. Looks like fodder for a green grant--it >>>> could be sooo much better with just a little invest-mint(tm). >>> >>> No one said it was useful for energy conversion. >>> >>> It's interesting, because normally non-linearity will only produce >>> harmonics, multiples, of the input frequency. This one also produces >>> sub-harmonics, at half the frequency in this case, just using a >>> single passive non-linear element. >>> >>> Jeroen Belleman >> >> Wow, but the half frequency output is soo poor. I think i can do =better.>> If i can figure it properly the ouput waveform will be much better and=i>> won't need a VCVS to "hide" an required amplifier to get it to be =barely>> usable. >> >> ?-) >> > >Please do. That would be interesting. > >Jeroen BellemanMy first two ideas didn't work out. ?-(
Reply by ●May 19, 20132013-05-19
On 2013-05-19 03:22, josephkk wrote:> On Tue, 07 May 2013 08:45:54 +0200, Jeroen Belleman <jeroen@nospam.please> > wrote: > >> On 2013-05-07 06:39, josephkk wrote: >>> On Fri, 03 May 2013 23:40:10 +0200, Jeroen <jeroen@nospam.please> wrote: >>> >>>> On 2013-05-03 23:23, dagmargoodboat@yahoo.com wrote: >>>>> On May 3, 3:39 pm, John Larkin <jlar...@highlandtechnology.com> wrote: >>>>>> On Fri, 3 May 2013 07:30:44 -0700 (PDT), dagmargoodb...@yahoo.com >>>>>> wrote: >>>>>> I did manage to sumulate a frequency divider of sorts, really a >>>>>> subcycle parametric oscillator, based on the C:V curve of a diode. It >>>>>> should work with a ceramic cap, too. But it's still pumped, not >>>>>> self-oscillating. >>>>>> >>>>>> https://dl.dropboxusercontent.com/u/53724080/Circuits/Oscillators/Sub... >>>>>> >>>>>> This is a classic diode frequency multiplier, but it halves the >>>>>> frequency instead of doubling it. Conversion efficiency is >>>>>> impressively bad. >>>>> >>>>> Yes, very impressively bad. Looks like fodder for a green grant--it >>>>> could be sooo much better with just a little invest-mint(tm). >>>> >>>> No one said it was useful for energy conversion. >>>> >>>> It's interesting, because normally non-linearity will only produce >>>> harmonics, multiples, of the input frequency. This one also produces >>>> sub-harmonics, at half the frequency in this case, just using a >>>> single passive non-linear element. >>>> >>>> Jeroen Belleman >>> >>> Wow, but the half frequency output is soo poor. I think i can do better. >>> If i can figure it properly the ouput waveform will be much better and i >>> won't need a VCVS to "hide" an required amplifier to get it to be barely >>> usable. >>> >>> ?-) >>> >> >> Please do. That would be interesting. >> >> Jeroen Belleman > > My first two ideas didn't work out. > > ?-(Thank you for trying. I believe simple non-linearity is not enough. A region of negative differential impedance is probably necessary, or some sort of storage effect. Either way, one needs a bifurcation in its phase space trajectory somewhere. Sinple non-linearity doesn't do that. I don't know what to make of John's results then. I should look into this in some more detail. So many projects, so little time... Jeroen Belleman
