Bob Widlar was a big engineer. Now, what is the significance of "Anybody can count to one"? Seems not to be a famous quote. --> John Dope <always.look@message.header> wrote in news:t6gdmo$or8$6@dont- > email.me: > >> jlarkin@highlandsniptechnology.com wrote: >> >>> Anybody can count to one. >>> >>> - Robert Widlar >> >> I don't get it. >> >> allintext:"Anybody can count to one" "Robert Widlar" >> >> Produces four results, all of them from John Larkin.
Crystal oven theory
Started by ●May 21, 2022
Reply by ●May 24, 20222022-05-24
Reply by ●May 24, 20222022-05-24
In article <t6hrnr$2ac$1@dont-email.me>, pNaonStpealmtje@yahoo.com says...> > On a sunny day (Mon, 23 May 2022 17:34:33 +0100) it happened Mike Coon > <gravity@mjcoon.plus.com> wrote in > <MPG.3cf5c7f82510056d9896bf@usenet.plus.net>: > > >In article <t6fga4$f2p$1@dont-email.me>, pNaonStpealmtje@yahoo.com > >says... > >> > >> On a sunny day (Sun, 22 May 2022 22:51:09 +0100) it happened Mike Coon > >> <gravity@mjcoon.plus.com> wrote in > >> <MPG.3cf4c0956a87c90d9896be@usenet.plus.net>: > >> > >> >My design for a foyer quartz clock back in the early 1960s included a > >> >crystal in a thermostatic oven made from Perspex. I have a sketch and > >> >isometric of the oven and a note that there were five thermistors in a > >> >bridge, but no schematic. I do remember that on first testing the > >> >control circuit initially ran at full power heating, then cut off, then > >> >gradually settled on steady warmth! > >> > >> Yes that is overshot, maybe over-compensated > > > >My definition of over-compensated would be indefinite oscillation, which > >is what I was concerned about when I was monitoring the behaviour... No > >theory involved! > > http://panteltje.com/pub/under_and_over_compensated_IXIMG_0818.JPGThanks for that idiosyncratic illustration! You could also have reminded me of the calculus of feedback theory which I studied for my degree back in the early 1960s. It was merely the modern (?) terminology I was querying. "Windup" indeed; that's a gramophone!
Reply by ●May 24, 20222022-05-24
On Tuesday, May 24, 2022 at 2:34:46 AM UTC+10, Mike Coon wrote:> In article <t6fga4$f2p$1...@dont-email.me>, pNaonSt...@yahoo.com > says... > > > > On a sunny day (Sun, 22 May 2022 22:51:09 +0100) it happened Mike Coon > > <gra...@mjcoon.plus.com> wrote in > > <MPG.3cf4c0956...@usenet.plus.net>: > > > > >My design for a foyer quartz clock back in the early 1960s included a > > >crystal in a thermostatic oven made from Perspex. I have a sketch and > > >isometric of the oven and a note that there were five thermistors in a > > >bridge, but no schematic. I do remember that on first testing the > > >control circuit initially ran at full power heating, then cut off, then > > >gradually settled on steady warmth! > > > > Yes that is overshot, maybe over-compensated > My definition of over-compensated would be indefinite oscillation, which > is what I was concerned about when I was monitoring the behaviour... No > theory involved!Clearly not. Most people understand over-compensated to mean very long settling times, and under-compensated to mean ringing. If it is second or or higher order system, a sufficiently undercompensates unit can oscillate. -- Bill Sloman, Sydney
Reply by ●May 24, 20222022-05-24
On Tue, 24 May 2022 08:41:01 +0100, Mike Coon <gravity@mjcoon.plus.com> wrote:>In article <t6hrnr$2ac$1@dont-email.me>, pNaonStpealmtje@yahoo.com >says... >> >> On a sunny day (Mon, 23 May 2022 17:34:33 +0100) it happened Mike Coon >> <gravity@mjcoon.plus.com> wrote in >> <MPG.3cf5c7f82510056d9896bf@usenet.plus.net>: >> >> >In article <t6fga4$f2p$1@dont-email.me>, pNaonStpealmtje@yahoo.com >> >says... >> >> >> >> On a sunny day (Sun, 22 May 2022 22:51:09 +0100) it happened Mike Coon >> >> <gravity@mjcoon.plus.com> wrote in >> >> <MPG.3cf4c0956a87c90d9896be@usenet.plus.net>: >> >> >> >> >My design for a foyer quartz clock back in the early 1960s included a >> >> >crystal in a thermostatic oven made from Perspex. I have a sketch and >> >> >isometric of the oven and a note that there were five thermistors in a >> >> >bridge, but no schematic. I do remember that on first testing the >> >> >control circuit initially ran at full power heating, then cut off, then >> >> >gradually settled on steady warmth! >> >> >> >> Yes that is overshot, maybe over-compensated >> > >> >My definition of over-compensated would be indefinite oscillation, which >> >is what I was concerned about when I was monitoring the behaviour... No >> >theory involved! >> >> http://panteltje.com/pub/under_and_over_compensated_IXIMG_0818.JPG > >Thanks for that idiosyncratic illustration! You could also have reminded >me of the calculus of feedback theory which I studied for my degree back >in the early 1960s. It was merely the modern (?) terminology I was >querying. "Windup" indeed; that's a gramophone!We usually tune thermal loops in the classic linear style, for critically-damped small signal disturbance. They will typically overshoot at cold-start powerup because the integrator winds up and rails. Rob did a lot of fancy math to define the software control loop; I just Spice things like that. The oven that I pictured has a 2nd order plant response, about 75 minutes tau for the huge aluminum block and about another 17 for the platform and e/o modulator inside. Spacers set the second time constant; aluminum, stainless, or plastic. One goal was to force minimal thermal gradients along the length of the Mach-Zender electro-optical modulator. https://www.dropbox.com/sh/knkoywpv6563mj5/AACy1sLNcyqIO8Eik4NRCC9Da?dl=0 We have lots of heater power available so we can stabilize to millikelvins in about a half hour. -- Anybody can count to one. - Robert Widlar
Reply by ●May 24, 20222022-05-24
jlarkin@highlandsniptechnology.com wrote:> On Tue, 24 May 2022 08:41:01 +0100, Mike Coon > <gravity@mjcoon.plus.com> wrote: > >> In article <t6hrnr$2ac$1@dont-email.me>, pNaonStpealmtje@yahoo.com >> says... >>> >>> On a sunny day (Mon, 23 May 2022 17:34:33 +0100) it happened Mike Coon >>> <gravity@mjcoon.plus.com> wrote in >>> <MPG.3cf5c7f82510056d9896bf@usenet.plus.net>: >>> >>>> In article <t6fga4$f2p$1@dont-email.me>, pNaonStpealmtje@yahoo.com >>>> says... >>>>> >>>>> On a sunny day (Sun, 22 May 2022 22:51:09 +0100) it happened Mike Coon >>>>> <gravity@mjcoon.plus.com> wrote in >>>>> <MPG.3cf4c0956a87c90d9896be@usenet.plus.net>: >>>>> >>>>>> My design for a foyer quartz clock back in the early 1960s included a >>>>>> crystal in a thermostatic oven made from Perspex. I have a sketch and >>>>>> isometric of the oven and a note that there were five thermistors in a >>>>>> bridge, but no schematic. I do remember that on first testing the >>>>>> control circuit initially ran at full power heating, then cut off, then >>>>>> gradually settled on steady warmth! >>>>> >>>>> Yes that is overshot, maybe over-compensated >>>> >>>> My definition of over-compensated would be indefinite oscillation, which >>>> is what I was concerned about when I was monitoring the behaviour... No >>>> theory involved! >>> >>> http://panteltje.com/pub/under_and_over_compensated_IXIMG_0818.JPG >> >> Thanks for that idiosyncratic illustration! You could also have reminded >> me of the calculus of feedback theory which I studied for my degree back >> in the early 1960s. It was merely the modern (?) terminology I was >> querying. "Windup" indeed; that's a gramophone! > > We usually tune thermal loops in the classic linear style, for > critically-damped small signal disturbance. They will typically > overshoot at cold-start powerup because the integrator winds up and > rails. Rob did a lot of fancy math to define the software control > loop; I just Spice things like that. > > The oven that I pictured has a 2nd order plant response, about 75 > minutes tau for the huge aluminum block and about another 17 for the > platform and e/o modulator inside. Spacers set the second time > constant; aluminum, stainless, or plastic. > > One goal was to force minimal thermal gradients along the length of > the Mach-Zender electro-optical modulator. > > https://www.dropbox.com/sh/knkoywpv6563mj5/AACy1sLNcyqIO8Eik4NRCC9Da?dl=0 > > We have lots of heater power available so we can stabilize to > millikelvins in about a half hour.One of the less-frequently remarked advantages of thermoelectrics is that anywhere near room temperature they can have considerably better forcing resistance than heater-only loops with a given bandwidth. A heater-only loop gets its negative slewing exclusively from the heat leak, which of course leaks in both directions, whereas a TEC can pull as well as push, so a TEC-based loop can be better insulated for the same control bandwidth and slew rate. 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 ●May 24, 20222022-05-24
bitrex <user@example.net> wrote in news:47UiK.3545$vAW9.2843@fx10.iad:> On 5/23/2022 6:05 PM, DecadentLinuxUserNumeroUno@decadence.org > wrote: >> bitrex <user@example.net> wrote in >> news:QaTiK.4601$8T.2667@fx40.iad: >> >>> On 5/23/2022 11:46 AM, jlarkin@highlandsniptechnology.com wrote: >>>> On Mon, 23 May 2022 14:11:54 -0000 (UTC), >>>> DecadentLinuxUserNumeroUno@decadence.org wrote: >>>> >>>>> jlarkin@highlandsniptechnology.com wrote in >>>>> news:4hjl8hd5d42lhge1c7lu0kt7m29led31kd@4ax.com: >>>>> >>>>>> On Sun, 22 May 2022 16:46:44 -0400, bitrex <user@example.net> >>>>>> wrote: >>>>>> >>>>>>> On 5/22/2022 2:21 PM, jlarkin@highlandsniptechnology.com >>>>>>> wrote: >>>>>>>> On Sun, 22 May 2022 13:24:02 -0400, bitrex >>>>>>>> <user@example.net> wrote: >>>>>>>> >>>>>>>>> On 5/22/2022 4:31 AM, Anthony William Sloman wrote: >>>>>>>>>> On Sunday, May 22, 2022 at 1:15:05 PM UTC+10, >>>>>>>>>> jla...@highlandsniptechnology.com wrote: >>>>>>>>>>> On Sat, 21 May 2022 20:50:12 -0400, bitrex >>>>>>>>>>> <us...@example.net> wrote: >>>>>>>>>>> >>>>>>>>>>>> Here's a paper on the theory of crystal ovens: >>>>>>>>>>>> >>>>>>>>>>>> <http://www.karlquist.com/oven.pdf> >>>>>>>>>> >>>>>>>>>> He didn't survey the literature all that well. >>>>>>>>>> >>>>>>>>>>>> There's a lot more to it than just slapping a crystal & >>>>>>>>>>>> heater in a metal box and calling it a day! There are >>>>>>>>>>>> probably some pathologically bad geometries even a >>>>>>>>>>>> really fast control loop can never stabilize very well. >>>>>>>>>>>> >>>>>>>>>>>> The part about the outer can acting like a Faraday >>>>>>>>>>>> shield is interesting, shunting ambient gradients >>>>>>>>>>>> around the core. Does anyone know how they make the >>>>>>>>>>>> negative space look like a linear tehrmal resistance >>>>>>>>>>>> over a wide range? There's some kind of insulating foam >>>>>>>>>>>> in there, is main heat thermal transfer radiative or >>>>>>>>>>>> conduction? >>>>>>>>>> >>>>>>>>>> Conduction. Foam pretty much stops convection. >>>>>>>>> >>>>>>>>> It was mentioned on another thread that the thermal >>>>>>>>> resistance of radiation between two concentric blackbodies >>>>>>>>> at 300K is about 6mm, interestingly that's very close to >>>>>>>>> the same thickness of foam-filled negative space between >>>>>>>>> the outer and inner shells of the OCXO module on my 5334B. >>>>>>>>> >>>>>>>>> Don't know if that's a coincidence or not, obviously the >>>>>>>>> two aren't at exactly 300K. The interior I think runs >>>>>>>>> about 355K, while the exterior (I haven't measured it) >>>>>>>>> seems cool enough to keep your hand on a while. >>>>>>>>> >>>>>>>> >>>>>>>> In a reasonably close-fitting box, without a lot of space >>>>>>>> for convection, air is a better thermal insulator than foam >>>>>>>> or fiberglass. >>>>>>>> >>>>>>> >>>>>>> Here's a glamour shot of the internals: >>>>>>> >>>>>>> <https://imgur.com/a/W4hmKt4> >>>>>>> >>>>>>> Don't know what the foam is. It doesn't seem to conduct heat >>>>>>> too good. >>>>>>> >>>>>>> >>>>>> >>>>>> The interesting test would be to measure heater power with >>>>>> and without the foam. >>>>>> >>>>>> >>>>>> >>>>> >>>>> The foam is for physical shock absorption, silly. >>>> >>>> None of my ovens depended on foam for mechanical support. >>>> Sometimes long lead wires are bad news too. >>>> >>>> I did mount one OCXO on some custom springs. Mating and >>>> unmating an nearby SMB test connector made my PLL lose lock. >>>> >>>> https://www.dropbox.com/s/0k8agdfyiqlwn84/Spring_2.JPG?raw=1 >>>> >>>> https://www.dropbox.com/s/l2gr4fxas2k05fz/Sprung_Osc_2.JPG?raw=1 >>>> >>>> >>>>> >>>>> Hard to protect against that "floating in air". They >>>>> should try >>>>> some nice aerogel inserts. I think it has pretty good >>>>> thermals compared to foam. >>>> >>>> Have you done that? Is aerogel rigid enough to support a >>>> subassembly? Would mechanical shocks scrunch it down? >>> >>> The foam inside the HP oven is stiff & brittle. I think it may >>> just be to separate the bits from each other and provide >>> mechanical support, but I don't think I'd want to rely on it to >>> absorb much shock. >>> >>> >> >> Compared to being suspended in air, I am sure it wil absorb more. >> Just what do you think "mechanical support" is? > > Do u require mechanical support:Look at it. It is smaller than the can it is in. So yes, it requires mechanical support. snipped retarded link post. Real mature, twerp.
Reply by ●May 24, 20222022-05-24
John Dope <always.look@message.header> wrote in news:t6hvrj$kq3$3@dont- email.me:> Bob Widlar was a big engineer. > > Now, what is the significance of "Anybody can count to one"? > > Seems not to be a famous quote. >John Dope is still in the dark. You never knew electronics and have been a mere interloper all these years, at best. The actual quote is "Every idiot can count to one." So even your google skill sucks. John Dope lives up to his name every time he posts into SED.
Reply by ●May 24, 20222022-05-24
On Tue, 24 May 2022 11:06:16 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>jlarkin@highlandsniptechnology.com wrote: >> On Tue, 24 May 2022 08:41:01 +0100, Mike Coon >> <gravity@mjcoon.plus.com> wrote: >> >>> In article <t6hrnr$2ac$1@dont-email.me>, pNaonStpealmtje@yahoo.com >>> says... >>>> >>>> On a sunny day (Mon, 23 May 2022 17:34:33 +0100) it happened Mike Coon >>>> <gravity@mjcoon.plus.com> wrote in >>>> <MPG.3cf5c7f82510056d9896bf@usenet.plus.net>: >>>> >>>>> In article <t6fga4$f2p$1@dont-email.me>, pNaonStpealmtje@yahoo.com >>>>> says... >>>>>> >>>>>> On a sunny day (Sun, 22 May 2022 22:51:09 +0100) it happened Mike Coon >>>>>> <gravity@mjcoon.plus.com> wrote in >>>>>> <MPG.3cf4c0956a87c90d9896be@usenet.plus.net>: >>>>>> >>>>>>> My design for a foyer quartz clock back in the early 1960s included a >>>>>>> crystal in a thermostatic oven made from Perspex. I have a sketch and >>>>>>> isometric of the oven and a note that there were five thermistors in a >>>>>>> bridge, but no schematic. I do remember that on first testing the >>>>>>> control circuit initially ran at full power heating, then cut off, then >>>>>>> gradually settled on steady warmth! >>>>>> >>>>>> Yes that is overshot, maybe over-compensated >>>>> >>>>> My definition of over-compensated would be indefinite oscillation, which >>>>> is what I was concerned about when I was monitoring the behaviour... No >>>>> theory involved! >>>> >>>> http://panteltje.com/pub/under_and_over_compensated_IXIMG_0818.JPG >>> >>> Thanks for that idiosyncratic illustration! You could also have reminded >>> me of the calculus of feedback theory which I studied for my degree back >>> in the early 1960s. It was merely the modern (?) terminology I was >>> querying. "Windup" indeed; that's a gramophone! >> >> We usually tune thermal loops in the classic linear style, for >> critically-damped small signal disturbance. They will typically >> overshoot at cold-start powerup because the integrator winds up and >> rails. Rob did a lot of fancy math to define the software control >> loop; I just Spice things like that. >> >> The oven that I pictured has a 2nd order plant response, about 75 >> minutes tau for the huge aluminum block and about another 17 for the >> platform and e/o modulator inside. Spacers set the second time >> constant; aluminum, stainless, or plastic. >> >> One goal was to force minimal thermal gradients along the length of >> the Mach-Zender electro-optical modulator. >> >> https://www.dropbox.com/sh/knkoywpv6563mj5/AACy1sLNcyqIO8Eik4NRCC9Da?dl=0 >> >> We have lots of heater power available so we can stabilize to >> millikelvins in about a half hour. > >One of the less-frequently remarked advantages of thermoelectrics is >that anywhere near room temperature they can have considerably better >forcing resistance than heater-only loops with a given bandwidth. > >A heater-only loop gets its negative slewing exclusively from the heat >leak, which of course leaks in both directions, whereas a TEC can pull >as well as push, so a TEC-based loop can be better insulated for the >same control bandwidth and slew rate. > >Cheers > >Phil HobbsWe only run at 30c, and ambient is very reliably 22. We considered TECs but that was too complex and expensive. We sure don't want a fan anywhere close to our optics. The dpak mosfet heaters are cheap! -- If a man will begin with certainties, he shall end with doubts, but if he will be content to begin with doubts he shall end in certainties. Francis Bacon
Reply by ●May 24, 20222022-05-24
Am 24.05.22 um 17:06 schrieb Phil Hobbs:> jlarkin@highlandsniptechnology.com wrote:he Mach-Zender electro-optical modulator.>> >> https://www.dropbox.com/sh/knkoywpv6563mj5/AACy1sLNcyqIO8Eik4NRCC9Da?dl=0 >> >> We have lots of heater power available so we can stabilize to >> millikelvins in about a half hour. > > One of the less-frequently remarked advantages of thermoelectrics is > that anywhere near room temperature they can have considerably better > forcing resistance than heater-only loops with a given bandwidth. > > A heater-only loop gets its negative slewing exclusively from the heat > leak, which of course leaks in both directions, whereas a TEC can pull > as well as push, so a TEC-based loop can be better insulated for the > same control bandwidth and slew rate.But a TEC has a thermal low-impedance-path from inside to the outside. That is unwanted and one of the reasons for their bad efficiency. That means that heat transients on the outside get in immediately and must be activly regulated away, AFTER they have happened. Yes, one could insulate the outside of the TEC, but that is somewhat ill? Cheers, Gerhard
Reply by ●May 24, 20222022-05-24
The proper quote helped. Thanks for doing that work for me, Always Insulting. DecadentLinuxUserNumeroUno@decadence.org wrote:> John Dope <always.look@message.header> wrote in news:t6hvrj$kq3$3@dont- > email.me: > >> Bob Widlar was a big engineer. >> >> Now, what is the significance of "Anybody can count to one"? >> >> Seems not to be a famous quote. >> > > John Dope is still in the dark. You never knew electronics and have > been a mere interloper all these years, at best. > > The actual quote is "Every idiot can count to one." > > So even your google skill sucks. John Dope lives up to his name > every time he posts into SED. >
