On 15/06/2020 12:12, Phil Allison wrote:> jla...@highlandsniptechnology.com wrote: > > ========================================= > >> >> Somebody here once measured self-discharge of some film caps, over >> years. I recall discharge levels something like one per cent per year. >> > > ** Must have been some large value polystyrene types. > > Lowest tempco and leakage of any film cap.Teflon might be lower leakage, but the only sources I know of are surplus USSR parts on ebay that are usually physically huge and of unknown and probably quite adventurous history, or by slaughtering a Tektronix scope, which ought to be illegal.
Some capacitor leakage measurements
Started by ●June 14, 2020
Reply by ●June 15, 20202020-06-15
Reply by ●June 17, 20202020-06-17
Chris Jones <lugnut808@spam.yahoo.com> wrote:> On 15/06/2020 12:12, Phil Allison wrote: >> jla...@highlandsniptechnology.com wrote: >> >> ========================================= >> >>> >>> Somebody here once measured self-discharge of some film caps, over >>> years. I recall discharge levels something like one per cent per year. >>> >> >> ** Must have been some large value polystyrene types. >> >> Lowest tempco and leakage of any film cap. > > Teflon might be lower leakage, but the only sources I know of are > surplus USSR parts on ebay that are usually physically huge and of > unknown and probably quite adventurous history, or by slaughtering a > Tektronix scope, which ought to be illegal.There's still plenty of teflon film cap makers in the US. Teflon caps have high temp ratings, that's about it. It's not the end-all dielectric material.
Reply by ●June 17, 20202020-06-17
Cydrome Leader wrote: ======================>>> > >>> Somebody here once measured self-discharge of some film caps, over > >>> years. I recall discharge levels something like one per cent per year. > >>> > >> > >> ** Must have been some large value polystyrene types. > >> > >> Lowest tempco and leakage of any film cap. > > > > Teflon might be lower leakage, but the only sources I know of are > > surplus USSR parts on ebay that are usually physically huge and of > > unknown and probably quite adventurous history, or by slaughtering a > > Tektronix scope, which ought to be illegal. > > There's still plenty of teflon film cap makers in the US. Teflon caps have > high temp ratings, that's about it. It's not the end-all dielectric > material. >** Like everyone knows ... noting stciks with Teflon. .... Phil
Reply by ●June 17, 20202020-06-17
On 17/06/2020 17:14, Cydrome Leader wrote:> Chris Jones <lugnut808@spam.yahoo.com> wrote: >> On 15/06/2020 12:12, Phil Allison wrote: >>> jla...@highlandsniptechnology.com wrote: >>> >>> ========================================= >>> >>>> >>>> Somebody here once measured self-discharge of some film caps, over >>>> years. I recall discharge levels something like one per cent per year. >>>> >>> >>> ** Must have been some large value polystyrene types. >>> >>> Lowest tempco and leakage of any film cap. >> >> Teflon might be lower leakage, but the only sources I know of are >> surplus USSR parts on ebay that are usually physically huge and of >> unknown and probably quite adventurous history, or by slaughtering a >> Tektronix scope, which ought to be illegal. > > There's still plenty of teflon film cap makers in the US. Teflon caps have > high temp ratings, that's about it. It's not the end-all dielectric > material.Yes, I had seen that there are companies that make them, however there are none at Mouser and there is only one range in digi-key and the largest value is 47pF, so I still consider them hard to get in higher capacitance values. Do you know of any distributors that stock a good range of them? I know they are not magical, but probably have slightly less leakage than polystyrene, and certainly a better combination of low leakage and also withstanding soldering temperatures.
Reply by ●June 17, 20202020-06-17
On 2020-06-17 09:02, Chris Jones wrote:> On 17/06/2020 17:14, Cydrome Leader wrote: >> Chris Jones <lugnut808@spam.yahoo.com> wrote: >>> On 15/06/2020 12:12, Phil Allison wrote: >>>> jla...@highlandsniptechnology.com wrote: >>>> >>>> ========================================= >>>> >>>>> >>>>> Somebody here once measured self-discharge of some film caps, over >>>>> years. I recall discharge levels something like one per cent per year. >>>>> >>>> >>>> ** Must have been some large value polystyrene types. >>>> >>>> Lowest tempco and leakage of any film cap. >>> >>> Teflon might be lower leakage, but the only sources I know of are >>> surplus USSR parts on ebay that are usually physically huge and of >>> unknown and probably quite adventurous history, or by slaughtering a >>> Tektronix scope, which ought to be illegal. >> >> There's still plenty of teflon film cap makers in the US. Teflon caps >> have >> high temp ratings, that's about it. It's not the end-all dielectric >> material. > > Yes, I had seen that there are companies that make them, however there > are none at Mouser and there is only one range in digi-key and the > largest value is 47pF, so I still consider them hard to get in higher > capacitance values. > > Do you know of any distributors that stock a good range of them? > > I know they are not magical, but probably have slightly less leakage > than polystyrene, and certainly a better combination of low leakage and > also withstanding soldering temperatures.Octopart doesn't have show high-value PTFE-dielectric caps in stock anywhere. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●June 17, 20202020-06-17
On Wednesday, June 17, 2020 at 1:03:09 PM UTC-4, Phil Hobbs wrote:> On 2020-06-17 09:02, Chris Jones wrote: > > On 17/06/2020 17:14, Cydrome Leader wrote: > >> Chris Jones <lugnut808@spam.yahoo.com> wrote: > >>> On 15/06/2020 12:12, Phil Allison wrote: > >>>> jla...@highlandsniptechnology.com wrote: > >>>> > >>>> ========================================= > >>>> > >>>>> > >>>>> Somebody here once measured self-discharge of some film caps, over > >>>>> years. I recall discharge levels something like one per cent per year. > >>>>> > >>>> > >>>> ** Must have been some large value polystyrene types. > >>>> > >>>> Lowest tempco and leakage of any film cap. > >>> > >>> Teflon might be lower leakage, but the only sources I know of are > >>> surplus USSR parts on ebay that are usually physically huge and of > >>> unknown and probably quite adventurous history, or by slaughtering a > >>> Tektronix scope, which ought to be illegal. > >> > >> There's still plenty of teflon film cap makers in the US. Teflon caps > >> have > >> high temp ratings, that's about it. It's not the end-all dielectric > >> material. > > > > Yes, I had seen that there are companies that make them, however there > > are none at Mouser and there is only one range in digi-key and the > > largest value is 47pF, so I still consider them hard to get in higher > > capacitance values. > > > > Do you know of any distributors that stock a good range of them? > > > > I know they are not magical, but probably have slightly less leakage > > than polystyrene, and certainly a better combination of low leakage and > > also withstanding soldering temperatures. > > Octopart doesn't have show high-value PTFE-dielectric caps in stock > anywhere. >Years ago I went searching for a teflon cap. The only ones I could find were on a audio oriented website. Which besides selling ~$50 teflon caps, suggested that they needed to be conditioned with broad band noise for several days. ('they' being the teflon caps and not the website. :^) George H.> Cheers > > Phil Hobbs > > -- > Dr Philip C D Hobbs > Principal Consultant > ElectroOptical Innovations LLC / Hobbs ElectroOptics > Optics, Electro-optics, Photonics, Analog Electronics > Briarcliff Manor NY 10510 > > http://electrooptical.net > http://hobbs-eo.com
Reply by ●June 17, 20202020-06-17
On Wed, 17 Jun 2020 13:03:00 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 2020-06-17 09:02, Chris Jones wrote: >> On 17/06/2020 17:14, Cydrome Leader wrote: >>> Chris Jones <lugnut808@spam.yahoo.com> wrote: >>>> On 15/06/2020 12:12, Phil Allison wrote: >>>>> jla...@highlandsniptechnology.com wrote: >>>>> >>>>> ========================================= >>>>> >>>>>> >>>>>> Somebody here once measured self-discharge of some film caps, over >>>>>> years. I recall discharge levels something like one per cent per year. >>>>>> >>>>> >>>>> ** Must have been some large value polystyrene types. >>>>> >>>>> ��� Lowest tempco and leakage of any film cap. >>>> >>>> Teflon might be lower leakage, but the only sources I know of are >>>> surplus USSR parts on ebay that are usually physically huge and of >>>> unknown and probably quite adventurous history, or by slaughtering a >>>> Tektronix scope, which ought to be illegal. >>> >>> There's still plenty of teflon film cap makers in the US. Teflon caps >>> have >>> high temp ratings, that's about it. It's not the end-all dielectric >>> material. >> >> Yes, I had seen that there are companies that make them, however there >> are none at Mouser and there is only one range in digi-key and the >> largest value is 47pF, so I still consider them hard to get in higher >> capacitance values. >> >> Do you know of any distributors that stock a good range of them? >> >> I know they are not magical, but probably have slightly less leakage >> than polystyrene, and certainly a better combination of low leakage and >> also withstanding soldering temperatures. > >Octopart doesn't have show high-value PTFE-dielectric caps in stock >anywhere. > >Cheers > >Phil HobbsDoes anyone have a use for super-low-leakage caps? Teflon has a horrible TC, so the voltage on a charged cap will change with temperature. That could look like leakage, or anti-leakage. Interesting: is the energy conserved after a temperature cycle? -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●June 17, 20202020-06-17
On Wednesday, June 17, 2020 at 2:38:22 PM UTC-4, John Larkin wrote:> On Wed, 17 Jun 2020 13:03:00 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > > >On 2020-06-17 09:02, Chris Jones wrote: > >> On 17/06/2020 17:14, Cydrome Leader wrote: > >>> Chris Jones <lugnut808@spam.yahoo.com> wrote: > >>>> On 15/06/2020 12:12, Phil Allison wrote: > >>>>> jla...@highlandsniptechnology.com wrote: > >>>>> > >>>>> ========================================= > >>>>> > >>>>>> > >>>>>> Somebody here once measured self-discharge of some film caps, over > >>>>>> years. I recall discharge levels something like one per cent per year. > >>>>>> > >>>>> > >>>>> ** Must have been some large value polystyrene types. > >>>>> > >>>>> Lowest tempco and leakage of any film cap. > >>>> > >>>> Teflon might be lower leakage, but the only sources I know of are > >>>> surplus USSR parts on ebay that are usually physically huge and of > >>>> unknown and probably quite adventurous history, or by slaughtering a > >>>> Tektronix scope, which ought to be illegal. > >>> > >>> There's still plenty of teflon film cap makers in the US. Teflon caps > >>> have > >>> high temp ratings, that's about it. It's not the end-all dielectric > >>> material. > >> > >> Yes, I had seen that there are companies that make them, however there > >> are none at Mouser and there is only one range in digi-key and the > >> largest value is 47pF, so I still consider them hard to get in higher > >> capacitance values. > >> > >> Do you know of any distributors that stock a good range of them? > >> > >> I know they are not magical, but probably have slightly less leakage > >> than polystyrene, and certainly a better combination of low leakage and > >> also withstanding soldering temperatures. > > > >Octopart doesn't have show high-value PTFE-dielectric caps in stock > >anywhere. > > > >Cheers > > > >Phil Hobbs > > Does anyone have a use for super-low-leakage caps? > > Teflon has a horrible TC, so the voltage on a charged cap will change > with temperature. That could look like leakage, or anti-leakage. > > Interesting: is the energy conserved after a temperature cycle?Are you asking how much heat is generated in a temperature cycle? That's where any inefficiency ends up. -- Rick C. - Get 1,000 miles of free Supercharging - Tesla referral code - https://ts.la/richard11209
Reply by ●June 17, 20202020-06-17
On 2020-06-17 14:38, John Larkin wrote:> On Wed, 17 Jun 2020 13:03:00 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 2020-06-17 09:02, Chris Jones wrote: >>> On 17/06/2020 17:14, Cydrome Leader wrote: >>>> Chris Jones <lugnut808@spam.yahoo.com> wrote: >>>>> On 15/06/2020 12:12, Phil Allison wrote: >>>>>> jla...@highlandsniptechnology.com wrote: >>>>>> >>>>>> ========================================= >>>>>> >>>>>>> >>>>>>> Somebody here once measured self-discharge of some film caps, over >>>>>>> years. I recall discharge levels something like one per cent per year. >>>>>>> >>>>>> >>>>>> ** Must have been some large value polystyrene types. >>>>>> >>>>>> Lowest tempco and leakage of any film cap. >>>>> >>>>> Teflon might be lower leakage, but the only sources I know of are >>>>> surplus USSR parts on ebay that are usually physically huge and of >>>>> unknown and probably quite adventurous history, or by slaughtering a >>>>> Tektronix scope, which ought to be illegal. >>>> >>>> There's still plenty of teflon film cap makers in the US. Teflon caps >>>> have >>>> high temp ratings, that's about it. It's not the end-all dielectric >>>> material. >>> >>> Yes, I had seen that there are companies that make them, however there >>> are none at Mouser and there is only one range in digi-key and the >>> largest value is 47pF, so I still consider them hard to get in higher >>> capacitance values. >>> >>> Do you know of any distributors that stock a good range of them? >>> >>> I know they are not magical, but probably have slightly less leakage >>> than polystyrene, and certainly a better combination of low leakage and >>> also withstanding soldering temperatures. >> >> Octopart doesn't have show high-value PTFE-dielectric caps in stock >> anywhere. >> >> Cheers >> >> Phil Hobbs > > Does anyone have a use for super-low-leakage caps? > > Teflon has a horrible TC, so the voltage on a charged cap will change > with temperature. That could look like leakage, or anti-leakage.Its glass transition is right around room temperature, so CTE and other TCs go nuts in a very inconvenient region.> > Interesting: is the energy conserved after a temperature cycle? >Should be--if the charge is conserved it can't do any net work on the outside world. I suppose the Coulomb force or the winding pressure could conceivably change the shape or microstructure of the dielectric if it got soft enough to creep. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●June 17, 20202020-06-17
On Wed, 17 Jun 2020 15:45:32 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 2020-06-17 14:38, John Larkin wrote: >> On Wed, 17 Jun 2020 13:03:00 -0400, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> On 2020-06-17 09:02, Chris Jones wrote: >>>> On 17/06/2020 17:14, Cydrome Leader wrote: >>>>> Chris Jones <lugnut808@spam.yahoo.com> wrote: >>>>>> On 15/06/2020 12:12, Phil Allison wrote: >>>>>>> jla...@highlandsniptechnology.com wrote: >>>>>>> >>>>>>> ========================================= >>>>>>> >>>>>>>> >>>>>>>> Somebody here once measured self-discharge of some film caps, over >>>>>>>> years. I recall discharge levels something like one per cent per year. >>>>>>>> >>>>>>> >>>>>>> ** Must have been some large value polystyrene types. >>>>>>> >>>>>>> ��� Lowest tempco and leakage of any film cap. >>>>>> >>>>>> Teflon might be lower leakage, but the only sources I know of are >>>>>> surplus USSR parts on ebay that are usually physically huge and of >>>>>> unknown and probably quite adventurous history, or by slaughtering a >>>>>> Tektronix scope, which ought to be illegal. >>>>> >>>>> There's still plenty of teflon film cap makers in the US. Teflon caps >>>>> have >>>>> high temp ratings, that's about it. It's not the end-all dielectric >>>>> material. >>>> >>>> Yes, I had seen that there are companies that make them, however there >>>> are none at Mouser and there is only one range in digi-key and the >>>> largest value is 47pF, so I still consider them hard to get in higher >>>> capacitance values. >>>> >>>> Do you know of any distributors that stock a good range of them? >>>> >>>> I know they are not magical, but probably have slightly less leakage >>>> than polystyrene, and certainly a better combination of low leakage and >>>> also withstanding soldering temperatures. >>> >>> Octopart doesn't have show high-value PTFE-dielectric caps in stock >>> anywhere. >>> >>> Cheers >>> >>> Phil Hobbs >> >> Does anyone have a use for super-low-leakage caps? >> >> Teflon has a horrible TC, so the voltage on a charged cap will change >> with temperature. That could look like leakage, or anti-leakage. > >Its glass transition is right around room temperature, so CTE and other >TCs go nuts in a very inconvenient region. > >> >> Interesting: is the energy conserved after a temperature cycle? >> > >Should be--if the charge is conserved it can't do any net work on the >outside world. I suppose the Coulomb force or the winding pressure >could conceivably change the shape or microstructure of the dielectric >if it got soft enough to creep.I was wondering what happens to the charge as it moves around through the glass transition. Fortunately, I don't use teflon caps! FR4 is bad enough. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
