Yes, that’s the one. A bit expensive, but current production. My guess is it's probably used for DWDM lasers in telecom. That said, call your local office and ask for a couple samples. I still think it would make a fine way to use AT cut crystals instead of SC because it will no longer matter if the crystal you have happens to have a turnover above or below rooom temperature....and there are two turnover temperatures...you could use either of above ambient is no longer a requirement. Get Outlook for iOS<https://aka.ms/o0ukef> ________________________________ From: Lux, Jim via time-nuts <time-nuts@lists.febo.com> Sent: Friday, March 31, 2023 6:27:59 PM To: time-nuts@lists.febo.com <time-nuts@lists.febo.com> Cc: Lux, Jim <jim@luxfamily.com> Subject: [time-nuts] Re: Temperature accuracy / repeatability / drift of double ovens On 3/31/23 4:04 PM, Richard (Rick) Karlquist via time-nuts wrote: > I believe that IC went out of production decades ago. > > Rick > https://www.analog.com/en/products/ltc1923.html#product-overview High Efficiency Thermoelectric Cooler Controller Example circuit is 0.01degree. Eval boards available too DC388C and DC491A Looks like a $40 part, with a $150 eval board. > On 3/31/2023 11:13 AM, Ed Marciniak via time-nuts wrote: >> Linear technology made a thermoelectric full H bridge temperature >> controller. At the time, I’d like to say it came as a lot of two >> components. The second was an op-amp that may have been selected or >> trimmed unless there was a good reason to include it with samples >> (maybe less commonly available). > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com > _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-leave@lists.febo.com

Am 2023-03-31 20:13, schrieb Ed Marciniak via time-nuts: > Linear technology made a thermoelectric full H bridge temperature > controller. At the time, I’d like to say it came as a lot of two > components. The second was an op-amp that may have been selected or > trimmed unless there was a good reason to include it with samples > (maybe less commonly available). > > It was supposed to be able to achieve 10 milliKelvin stability easily, > and with more care in design, 1 milliKelvin stability was supposed to > be not too difficult to achieve. That really gives me some hope, I'll take the care :-) The question is now how to prove it! > It was a moderately expensive part…about $20 for the two components. A > handful of passives and a a pair of N-channel and a pair of P-channel > MOSFETs were required. > > If memory serves correctly it was also switched mode rather than > linear. Thanks for the pointer, also to Jim Lux. As a first try, I used the Analog Devices ADN 8834, also from AD, now that they have bought LT. But the Linear Technology LTC1923 data sheet is in a different league, they even give absolute numbers and strip charts. I'd bet that this went over the desk of Jim Williams, RIP. Simply top notch. The ADN8843 has the H-Bridge built-in and it worked for someone I know. I'm not too excited by the cascaded TECs. They can only provide a temperature difference, and absolute temperature only with a regulation loop with more time constants between the TEC and the NTC. The low thermal impedance path through the TEC is a real drawback, and probably the culprit for the low efficiency. No wonder that no one uses them in OCXOs. But 87°C like in my Morion OCXOs is no solution, either, even if we could dim down the absolute temperature. > From: Bob Camp via time-nuts <time-nuts@lists.febo.com> > Sent: Thursday, March 30, 2023 6:01:55 PM > Thermal gain on a single oven is likely in the 300 to 600 range. > > Double oven boosts that by 10 to 30X > > Thermal gain in this case: take the ambient change divide it by the > thermal gain > and you get the oven temperature change. > > Long term stability: > > low enough that it does not impact aging. ( = that’s how you test it). > Since that gets back > to the specific thermistor being used, you are into the ‘likely not > much help” range. > > Best guess info: The crystal + circuit is < 1x10^-9 / C in the > vicinity of the turn. The operating > point is offset from turn to minimize the combination of crystal + > circuit. Just what the net > is …. No crystal today, just VCSELs... > Still, if you can “see” aging at the parts in the (low?) 10^-11 range, > it sort of kind of gets > you to a number. Maybe 0.01C / day. >> Cheers, Gerhard

Hi They tried that (cooling vs heating) back in the 1950’s. It created more issues (heat sinking the lossy TEC’s, poor TEC reliability, ….. ) than it fixed. Bob > On Mar 31, 2023, at 10:22 PM, Ed Marciniak via time-nuts <time-nuts@lists.febo.com> wrote: > > Yes, that’s the one. A bit expensive, but current production. > > My guess is it's probably used for DWDM lasers in telecom. > > That said, call your local office and ask for a couple samples. > > I still think it would make a fine way to use AT cut crystals instead of SC because it will no longer matter if the crystal you have happens to have a turnover above or below rooom temperature....and there are two turnover temperatures...you could use either of above ambient is no longer a requirement. > > Get Outlook for iOS<https://aka.ms/o0ukef> > ________________________________ > From: Lux, Jim via time-nuts <time-nuts@lists.febo.com> > Sent: Friday, March 31, 2023 6:27:59 PM > To: time-nuts@lists.febo.com <time-nuts@lists.febo.com> > Cc: Lux, Jim <jim@luxfamily.com> > Subject: [time-nuts] Re: Temperature accuracy / repeatability / drift of double ovens > > On 3/31/23 4:04 PM, Richard (Rick) Karlquist via time-nuts wrote: >> I believe that IC went out of production decades ago. >> >> Rick >> > https://www.analog.com/en/products/ltc1923.html#product-overview > > > High Efficiency Thermoelectric Cooler Controller > > Example circuit is 0.01degree. > > Eval boards available too DC388C and DC491A > > > Looks like a $40 part, with a $150 eval board. > > > > > > >> On 3/31/2023 11:13 AM, Ed Marciniak via time-nuts wrote: >>> Linear technology made a thermoelectric full H bridge temperature >>> controller. At the time, I’d like to say it came as a lot of two >>> components. The second was an op-amp that may have been selected or >>> trimmed unless there was a good reason to include it with samples >>> (maybe less commonly available). >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe send an email to time-nuts-leave@lists.febo.com >> > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

Hello, Of course, the data sheet has Jim Williams signature. Take a look to his app note https://www.analog.com/media/en/technical-documentation/application-notes/an89.pdf and don't miss the last page :) Regards, Javier, EA1CRB On 4/1/23 23:11, Gerhard Hoffmann via time-nuts wrote: > Am 2023-03-31 20:13, schrieb Ed Marciniak via time-nuts: >> Linear technology made a thermoelectric full H bridge temperature >> controller. At the time, I’d like to say it came as a lot of two >> components. The second was an op-amp that may have been selected or >> trimmed unless there was a good reason to include it with samples >> (maybe less commonly available). >> >> It was supposed to be able to achieve 10 milliKelvin stability easily, >> and with more care in design, 1 milliKelvin stability was supposed to >> be not too difficult to achieve. > > That really gives me some hope, I'll take the care :-) > The question is now how to prove it! > > >> It was a moderately expensive part…about $20 for the two components. A >> handful of passives and a a pair of N-channel and a pair of P-channel >> MOSFETs were required. >> >> If memory serves correctly it was also switched mode rather than linear. > > Thanks for the pointer, also to Jim Lux. > > As a first try, I used the Analog Devices ADN 8834, also from AD, now > that > they have bought LT. But the Linear Technology LTC1923 data sheet is in > a different league, they even give absolute numbers and strip charts. > I'd bet that this went over the desk of Jim Williams, RIP. Simply top > notch. > The ADN8843 has the H-Bridge built-in and it worked for someone I know. > > I'm not too excited by the cascaded TECs. They can only provide a > temperature difference, and absolute temperature only with a regulation > loop with more time constants between the TEC and the NTC. The low > thermal > impedance path through the TEC is a real drawback, and probably the > culprit for the low efficiency. No wonder that no one uses them in OCXOs. > But 87°C like in my Morion OCXOs is no solution, either, even if we could > dim down the absolute temperature. > > >> From: Bob Camp via time-nuts <time-nuts@lists.febo.com> >> Sent: Thursday, March 30, 2023 6:01:55 PM > >> Thermal gain on a single oven is likely in the 300 to 600 range. >> >> Double oven boosts that by 10 to 30X >> >> Thermal gain in this case: take the ambient change divide it by the >> thermal gain >> and you get the oven temperature change. >> >> Long term stability: >> >> low enough that it does not impact aging. ( = that’s how you test it). >> Since that gets back >> to the specific thermistor being used, you are into the ‘likely not >> much help” range. >> >> Best guess info: The crystal + circuit is < 1x10^-9 / C in the >> vicinity of the turn. The operating >> point is offset from turn to minimize the combination of crystal + >> circuit. Just what the net >> is …. > > No crystal today, just VCSELs... > >> Still, if you can “see” aging at the parts in the (low?) 10^-11 range, >> it sort of kind of gets >> you to a number. Maybe 0.01C / day. > > >>> Cheers, Gerhard > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

Also any devotees of Jim should not miss his foot note: Page 5 Note 6 of the data sheet https://www.analog.com/media/en/technical-documentation/application-notes/an89.pdf Lester B Veenstra K1YCM MØYCM W8YCM 6Y6Y W8YCM/6Y 6Y8LV (Reformed USNSG CTM1) lester@veenstras.com 452 Stable Ln Keyser WV 26726 USA GPS: 39.336826 N 78.982287 W (Google) GPS: 39.33682 N 78.9823741 W (GPSDO) Telephones: Home: +1-304-289-6057 US cell +1-304-790-9192 Jamaica cell: +1-876-456-8898 -----Original Message----- From: Javier Herrero via time-nuts [mailto:time-nuts@lists.febo.com] Sent: Sunday, April 2, 2023 4:42 PM To: time-nuts@lists.febo.com Cc: Javier Herrero Subject: [time-nuts] Re: Temperature accuracy / repeatability / drift of double ovens Hello, Of course, the data sheet has Jim Williams signature. Take a look to his app note https://www.analog.com/media/en/technical-documentation/application-notes/an89.pdf and don't miss the last page :) Regards, Javier, EA1CRB