Re: [time-nuts] Frequency referenced temperature regulator
Hi If you run through the major distributors, there are a wide variety of parts available. You either dig in on thermistors or on RTD's. The RTD is more linear and normally made from platinum. The thermistor is a better choice for a single point controller. Both are available in glass packages for sub $5 prices. Traditionally the glass parts have been the most stable. You can go off to people like Hart and get stainless steel sheathed versions of either one that are certified to be quite accurate over a very wide range. You will pay a bit more for the high accuracy stuff (like kilo bucks). Bob On Nov 11, 2010, at 12:02 AM, Perry Sandeen wrote: List, Looking for a stable temperature sensor I first went to YSI. They have sold their sensor products to. Measurement Specialties, Inc. Perusing their site I came upon a Ni1000 SOT temperature sensor. It is a nickel based unit that has a basic resistance of 1K ohms at 20 degrees C and rising to 1482 ohms at 80 degrees C. . It has close to a 6 ohm change per degree. I tried to find one of their distributors without success. Entering the part number in Google, I found it is also made by ZETEX. ZETEX calls it an IC TEMP SENSOR NI1000 SOT23-3. The Digi-Key catalog as part number is ZNI1000CT ND. They are $2.77 each. The ZETEX data sheet has a nice circuit for a digital thermometer. Perhaps a LM 331 precision voltage-to-frequency IC or using a change in a bridge circuit to a varactor on a VCXO might provide the lack of aging problems that exist with a thermistor when precisely trying to obtain a temperature-to-frequency conversion. From another site: DIGI-KEY Did you know that you can get FREE shipping on your order? Yes, that's correct -- no minimum order fee and no shipping charges. The secret is that you must send them a check or money order by mail. Time-wise, it will add a couple days to get your parts over ordering them via internet or phone -- the time it takes your letter to get to Minnesota. (See their terms and conditions on their website -- they cover themselves for very heavy cheap items.) Regards, Perrier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
Nickel sensors are more stable than thermistors, but not as stable as platinum. The cost is more attractive than Pt, tho. I'd consider staying analog with a DC bridge and a PID control op-amp. You don't need a highly accurate voltage source for the bridge because null is null, whatever the excitation voltage. Of course, you'll want a stable null for the op-amp, too. You do need a highly stable set of bridge resistors for a stable temperature. In the old days, precision, stable resistors were wound on ceramic forms by soldering a loop of e.g. constantan wire to the lead wires at each end of the form. Then you pull the loop at the center so that you can wind it on the core in a non-inductive manner. Inductance doesn't matter, but you want to finish the winding with the center bent double and sticking out a few inches from the core. Attach the lead wires to a measuring device with sufficient precision and accuracy, and hope that the winding has slightly more resistance than you want. Now take a razor blade and short the center wires closer to the winding. The resistance should go down. When you find the spot that gives the right resistance, remove the insulation and solder the wires together. Don't even think of using any kind of variable resistor to adjust the bridge null. What you want is a stable temperature near the value that gives the least crystal tempco. Yes, this is also how to make a meter shunt, but you'll be using much finer wire. The best thing to do might be to find an antique precision resistance bridge. It will have many such resistors in it, and you might be able to avoid winding altogether. Please write for details. Bill Hawkins -Original Message- From: Perry Sandeen Sent: Wednesday, November 10, 2010 11:03 PM List, Looking for a stable temperature sensor I first went to YSI. They have sold their sensor products to. Measurement Specialties, Inc. Perusing their site I came upon a Ni1000 SOT temperature sensor. It is a nickel based unit that has a basic resistance of 1K ohms at 20 degrees C and rising to 1482 ohms at 80 degrees C. . It has close to a 6 ohm change per degree. I tried to find one of their distributors without success. Entering the part number in Google, I found it is also made by ZETEX. ZETEX calls it an IC TEMP SENSOR NI1000 SOT23-3. The Digi-Key catalog as part number is ZNI1000CT ND. They are $2.77 each. The ZETEX data sheet has a nice circuit for a digital thermometer. Perhaps a LM 331 precision voltage-to-frequency IC or using a change in a bridge circuit to a varactor on a VCXO might provide the lack of aging problems that exist with a thermistor when precisely trying to obtain a temperature-to-frequency conversion. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
Hi Depends on where you filter it. If you get a oscillator going that also mixes, the frequency difference will come out directly. Getting that all done at once may be a bit tricky. Bob On Nov 9, 2010, at 1:55 AM, Magnus Danielson wrote: On 11/09/2010 12:51 AM, Bob Camp wrote: Hi You can do very much the same thing by getting an SC to run on both the B and C modes at the same time. Hmm. Yes, but filtering will be a bit more trickier? Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
Sounds like the way the HP 2804 quartz thermometer works. HP came up with a special crystal cut that was very linear with temp, and I suspect the hardest part of your idea might be the linearity of the tempco of your crystal. But you could characterize that and store in a correction table. John On Nov 8, 2010, at 10:04 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: I'm contemplating building a small temperature control enclosure for testing various electronics. I have a handful of peltiers suitable for the purpose, and was pondering the right control mechanism. Most people would reach for a NTC, put it in a wien-brige etc etc. But since I happen to have access to much more stable frequencies than voltages, I thought of a different way: 1. Mount a X-tal-osc with really lousy tempco inside the enclosure. 2. Compare its output to a stable reference frequency. 3. Use the output of the phase comparator to drive the Peltier. It is basically a PLL where temperature is used as EFC... Has anybody tried that ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
This project has to qualify for the *Yes, I Really AM a Time Nut*certificate. [?] I can fix you up with a temperature monitor that will page you or text your cell phone if the temp goes out of range. Let us know how it goes. On Mon, Nov 8, 2010 at 10:04 AM, Poul-Henning Kamp p...@phk.freebsd.dkwrote: I'm contemplating building a small temperature control enclosure for testing various electronics. I have a handful of peltiers suitable for the purpose, and was pondering the right control mechanism. Most people would reach for a NTC, put it in a wien-brige etc etc. But since I happen to have access to much more stable frequencies than voltages, I thought of a different way: 1. Mount a X-tal-osc with really lousy tempco inside the enclosure. 2. Compare its output to a stable reference frequency. 3. Use the output of the phase comparator to drive the Peltier. It is basically a PLL where temperature is used as EFC... Has anybody tried that ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. 338.gif___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
On 11/8/2010 9:04 AM, Poul-Henning Kamp wrote: But since I happen to have access to much more stable frequencies than voltages, I thought of a different way: 1. Mount a X-tal-osc with really lousy tempco inside the enclosure. 2. Compare its output to a stable reference frequency. 3. Use the output of the phase comparator to drive the Peltier. It is basically a PLL where temperature is used as EFC... Has anybody tried that ? It's been my experience that oscillators with really lousy temperature performance have really lousy repeatability as well. I'm never delved into why this is true, but I suspect it's a number of things and not limited to the quartz resonator. -- mailto:o...@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
Hi John: Is there a source of crystals cut for temperature measurements? Have Fun, Brooke Clarke http://www.PRC68.com John Ackermann N8UR wrote: Sounds like the way the HP 2804 quartz thermometer works. HP came up with a special crystal cut that was very linear with temp, and I suspect the hardest part of your idea might be the linearity of the tempco of your crystal. But you could characterize that and store in a correction table. John On Nov 8, 2010, at 10:04 AM, Poul-Henning Kampp...@phk.freebsd.dk wrote: I'm contemplating building a small temperature control enclosure for testing various electronics. I have a handful of peltiers suitable for the purpose, and was pondering the right control mechanism. Most people would reach for a NTC, put it in a wien-brige etc etc. But since I happen to have access to much more stable frequencies than voltages, I thought of a different way: 1. Mount a X-tal-osc with really lousy tempco inside the enclosure. 2. Compare its output to a stable reference frequency. 3. Use the output of the phase comparator to drive the Peltier. It is basically a PLL where temperature is used as EFC... Has anybody tried that ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
In message 6b9c616f-5c27-4f36-9594-fda27d949...@febo.com, John Ackermann N8UR writes: Sounds like the way the HP 2804 quartz thermometer works. HP came up with a special crystal cut that was very linear with temp, and I suspect the hardest part of your idea might be the linearity of the tempco of your crystal. But you could characterize that and store in a correction table. Indeed, it was the HP2804 that gave me the idea. The correction table would more or less be the frequency I key into my HP3336 to get a given temperature. My plan was to add a separate pt1000 element to measure the absolute temperature. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
Hi Actually the biggest issue is hysteresis. That's what killed the 2804. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of John Ackermann N8UR Sent: Monday, November 08, 2010 10:14 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Frequency referenced temperature regulator Sounds like the way the HP 2804 quartz thermometer works. HP came up with a special crystal cut that was very linear with temp, and I suspect the hardest part of your idea might be the linearity of the tempco of your crystal. But you could characterize that and store in a correction table. John On Nov 8, 2010, at 10:04 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: I'm contemplating building a small temperature control enclosure for testing various electronics. I have a handful of peltiers suitable for the purpose, and was pondering the right control mechanism. Most people would reach for a NTC, put it in a wien-brige etc etc. But since I happen to have access to much more stable frequencies than voltages, I thought of a different way: 1. Mount a X-tal-osc with really lousy tempco inside the enclosure. 2. Compare its output to a stable reference frequency. 3. Use the output of the phase comparator to drive the Peltier. It is basically a PLL where temperature is used as EFC... Has anybody tried that ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
At 09:04 AM 11/8/2010, Poul-Henning Kamp wrote: 1. Mount a X-tal-osc with really lousy tempco inside the enclosure. 2. Compare its output to a stable reference frequency. 3. Use the output of the phase comparator to drive the Peltier. It is basically a PLL where temperature is used as EFC... Has anybody tried that ? I think Jim Williams did a quartz based thermometer in one of the old LTC app notes. I *think* the crystal manufacturer and part number was spec'd in the note. -- newell N5TNL ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
Poul-Henning Kamp wrote: I'm contemplating building a small temperature control enclosure for testing various electronics. I have a handful of peltiers suitable for the purpose, and was pondering the right control mechanism. Most people would reach for a NTC, put it in a wien-brige etc etc. But since I happen to have access to much more stable frequencies than voltages, I thought of a different way: 1. Mount a X-tal-osc with really lousy tempco inside the enclosure. 2. Compare its output to a stable reference frequency. 3. Use the output of the phase comparator to drive the Peltier. It is basically a PLL where temperature is used as EFC... Has anybody tried that ? I used to work at a place where we used SAW resonators as sensors for just about everything (including temperature, pressure, force, chemical presence), and pretty much as you describe.. output of resonator affected by what you wanted to measure was mixed with a similar resonator which was not, and a microcontroller would count the difference frequency and do what ever else was needed (run control loop, apply cal curve, etc.) There's also the whole MCXO scheme, where you compare the fundamental and 3rd overtone, and measure the temperature of the crystal that way (in order to adjust the output frequency of a DDS driven by the oscillator) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
Hi, Why not use a more conventional approach using a good thermistor and a PWM IC? I built some in the past with Peltiers and an LM3524 for cooling a photomultiplier in a nitrogen oxyde analyzer, and the result was quite good. I also used the same approach (but not with Peltier) for heating. Of course, the frequency stability was not time-nuts grade... not even near :) NTCs like the YSI 44031 have very good repeatabilty, and the resistance vs. temperature curve is quite steep, so you really don't need too stringent voltage stability needs. Regards, Javier El 08/11/2010 16:04, Poul-Henning Kamp escribió: I'm contemplating building a small temperature control enclosure for testing various electronics. I have a handful of peltiers suitable for the purpose, and was pondering the right control mechanism. Most people would reach for a NTC, put it in a wien-brige etc etc. But since I happen to have access to much more stable frequencies than voltages, I thought of a different way: 1. Mount a X-tal-osc with really lousy tempco inside the enclosure. 2. Compare its output to a stable reference frequency. 3. Use the output of the phase comparator to drive the Peltier. It is basically a PLL where temperature is used as EFC... Has anybody tried that ? -- Javier HerreroEMAIL: jherr...@hvsistemas.com Chief Technology Officer HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
Oz-in-DFW wrote: On 11/8/2010 9:04 AM, Poul-Henning Kamp wrote: But since I happen to have access to much more stable frequencies than voltages, I thought of a different way: 1. Mount a X-tal-osc with really lousy tempco inside the enclosure. Has anybody tried that ? It's been my experience that oscillators with really lousy temperature performance have really lousy repeatability as well. I'm never delved into why this is true, but I suspect it's a number of things and not limited to the quartz resonator. Depends on *why* it's a lousy temp performance.. is it that the crystal has poor performance OR that the crystal is low Q (e.g. in a TCXO) and the frequency is affected by the other component variations in the circuit. There are some circuits where the bias changes with temperature, and therefore, the power (and hence heating) through the crystal changes, for instance. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
Poul-Henning Kamp wrote: But since I happen to have access to much more stable frequencies than voltages, I thought of a different way: 1. Mount a X-tal-osc with really lousy tempco inside the enclosure. 2. Compare its output to a stable reference frequency. 3. Use the output of the phase comparator to drive the Peltier. It is basically a PLL where temperature is used as EFC... Has anybody tried that ? Frequency comparison between two oscillators, one a low-tempco and the other a high-tempco, is used by Dallas in the new version of the infamous (to Time Nuts) DS1620 temperature sensor. See the current datasheet and Dallas AN-105. I assume neither is an XO, nor do they phase lock them. Instead, they count the higher-frequency, low-tempco oscillator using the lower-frequency, high-tempco oscillator as a time base, then correct for nonlinearities. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
Hi The crystal in the temperature probes was an LC cut. There are a number of temperature dependant cuts out there for BAW's. SAW's have their own families of cuts. One of the drivers for running the probes at the frequency they chose was the small crystal package they wanted to use. Tough to fit a 5 MHz 3rd overtone in a TO-5 package. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of John Ackermann N8UR Sent: Monday, November 08, 2010 11:26 AM To: Discussion of precise time and frequency measurement Cc: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Frequency referenced temperature regulator I've never looked. The original HP Journal article talked about the characteristics of the crystal. I think it's called an L cut. The frequency used was around 26 MHz because that yielded an easy Hz/degree ratio. On Nov 8, 2010, at 10:21 AM, Brooke Clarke bro...@pacific.net wrote: Hi John: Is there a source of crystals cut for temperature measurements? Have Fun, Brooke Clarke http://www.PRC68.com John Ackermann N8UR wrote: Sounds like the way the HP 2804 quartz thermometer works. HP came up with a special crystal cut that was very linear with temp, and I suspect the hardest part of your idea might be the linearity of the tempco of your crystal. But you could characterize that and store in a correction table. John On Nov 8, 2010, at 10:04 AM, Poul-Henning Kampp...@phk.freebsd.dk wrote: I'm contemplating building a small temperature control enclosure for testing various electronics. I have a handful of peltiers suitable for the purpose, and was pondering the right control mechanism. Most people would reach for a NTC, put it in a wien-brige etc etc. But since I happen to have access to much more stable frequencies than voltages, I thought of a different way: 1. Mount a X-tal-osc with really lousy tempco inside the enclosure. 2. Compare its output to a stable reference frequency. 3. Use the output of the phase comparator to drive the Peltier. It is basically a PLL where temperature is used as EFC... Has anybody tried that ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
Hi The nice thing about a SAW is that you can bond it directly to the surface being measured. That reduces lag quite a bit. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of jimlux Sent: Monday, November 08, 2010 10:33 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Frequency referenced temperature regulator Poul-Henning Kamp wrote: I'm contemplating building a small temperature control enclosure for testing various electronics. I have a handful of peltiers suitable for the purpose, and was pondering the right control mechanism. Most people would reach for a NTC, put it in a wien-brige etc etc. But since I happen to have access to much more stable frequencies than voltages, I thought of a different way: 1. Mount a X-tal-osc with really lousy tempco inside the enclosure. 2. Compare its output to a stable reference frequency. 3. Use the output of the phase comparator to drive the Peltier. It is basically a PLL where temperature is used as EFC... Has anybody tried that ? I used to work at a place where we used SAW resonators as sensors for just about everything (including temperature, pressure, force, chemical presence), and pretty much as you describe.. output of resonator affected by what you wanted to measure was mixed with a similar resonator which was not, and a microcontroller would count the difference frequency and do what ever else was needed (run control loop, apply cal curve, etc.) There's also the whole MCXO scheme, where you compare the fundamental and 3rd overtone, and measure the temperature of the crystal that way (in order to adjust the output frequency of a DDS driven by the oscillator) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
In message 79b9c6dd6ac84dd0b38bc8ca0450d...@vectron.com, Bob Camp writes: Hi The nice thing about a SAW is that you can bond it directly to the surface being measured. That reduces lag quite a bit. You can do the same by using a modern SMD X-tal... And I don't have ready access to SAW devices, whereas I have tons of Xtals of all sorts in my junkbox. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
In message 20101108153647.495ce11b...@karen.lavabit.com, Charles P. Steinmet z writes: Frequency comparison between two oscillators, one a low-tempco and the other a high-tempco, is used by Dallas [...] I assume neither is an XO [...] They are silicon timed devices which I suspect is really a RC-oscillator in silicon... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
Hi A lot will depend on the internal construction of the SMD crystal. You would want to avoid evacuated packages. They will indeed respond much faster than a conventional leaded BAW. You may be surprised at just how good the tempco is on your junk box crystals. For a good thermometer cut you want something above 10 ppm / C. To get that with an AT bar, you just about have to put it in the dicing saw backwards. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Poul-Henning Kamp Sent: Monday, November 08, 2010 11:53 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Frequency referenced temperature regulator In message 79b9c6dd6ac84dd0b38bc8ca0450d...@vectron.com, Bob Camp writes: Hi The nice thing about a SAW is that you can bond it directly to the surface being measured. That reduces lag quite a bit. You can do the same by using a modern SMD X-tal... And I don't have ready access to SAW devices, whereas I have tons of Xtals of all sorts in my junkbox. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
But since I happen to have access to much more stable frequencies than voltages, I thought of a different way: 1. Mount a X-tal-osc with really lousy tempco inside the enclosure 2. Compare its output to a stable reference frequency. 3. Use the output of the phase comparator to drive the Peltier. It is basically a PLL where temperature is used as EFC.. SC-cut crystals have a linear (but I don't know how linear!) negative TC in the B-mode. A quick search didn't throw up much literature on the subject. I recently tried 2 separate 100MHz 5th-overtone crystals (same spec, different batches) in the same oscillator, tuned for the B-mode. The frequency change from +25 to +85°C appeared to be well within 1% for the 2 crystals, with a mean TC of ~ -27.8ppm/deg C. I didn't dwell long enough at intermediate temperatures to check the linearity accurately, but they looked quite linear at first sight. If you have an OCXO surplus to requirements, with an SC-cut crystal, you could try tuning it to oscillate in the B-mode (typically ~ 9-10% high), disconnect the heater and calibrate its frequency against temperature. (Of course you will need a calibrated oven to do this...) Garry Pascall Electronics Ltd - Registered in England No: 1316674 VAT Registration No: GB 448705134 Registered Office: Brunswick Road, Cobbs Wood, Ashford, Kent, TN23 1EH The transfer of any controlled technology contained in or attached to this email is covered by the Open General Export Licence (Technology for Military Goods), granted by the United Kingdom Secretary of State. GBOGE2008/01354 The information contained in this email is provided as a personal communication of the sender and, as such, is not binding on Pascall Electronics Ltd. unless the intended recipient has been notified by signed postal or fax communication that the sender is authorised to commit Pascall Electronics Ltd. on the subject matter concerned.The contents of this email are confidential to the intended recipient at the email address to which it has been addressed. It may not be disclosed to or used by anyone other than this addressee, nor may it be copied in any way. If received in error, please contact Oli Poole, at opo...@pascall.co.uk, quoting the name of the sender and the addressee and then delete it from your system. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
Poul-Henning, On 11/08/2010 04:04 PM, Poul-Henning Kamp wrote: I'm contemplating building a small temperature control enclosure for testing various electronics. I have a handful of peltiers suitable for the purpose, and was pondering the right control mechanism. Most people would reach for a NTC, put it in a wien-brige etc etc. But since I happen to have access to much more stable frequencies than voltages, I thought of a different way: 1. Mount a X-tal-osc with really lousy tempco inside the enclosure. 2. Compare its output to a stable reference frequency. 3. Use the output of the phase comparator to drive the Peltier. It is basically a PLL where temperature is used as EFC... Has anybody tried that ? Have a look at microprocessor compensated crystal oscillators. It runs the oscillator in both basic and third overtone at the same time. By measuring the beat frequency between the modes, the temperature can be measured. See the John Vig presentation http://www.am1.us/Papers/U11625 VIG-TUTORIAL.PDF starting at page 43. I see no reason why it could not be used to stabilize the temperature. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
Hi You can do very much the same thing by getting an SC to run on both the B and C modes at the same time. Bob On Nov 8, 2010, at 6:04 PM, Magnus Danielson wrote: Poul-Henning, On 11/08/2010 04:04 PM, Poul-Henning Kamp wrote: I'm contemplating building a small temperature control enclosure for testing various electronics. I have a handful of peltiers suitable for the purpose, and was pondering the right control mechanism. Most people would reach for a NTC, put it in a wien-brige etc etc. But since I happen to have access to much more stable frequencies than voltages, I thought of a different way: 1. Mount a X-tal-osc with really lousy tempco inside the enclosure. 2. Compare its output to a stable reference frequency. 3. Use the output of the phase comparator to drive the Peltier. It is basically a PLL where temperature is used as EFC... Has anybody tried that ? Have a look at microprocessor compensated crystal oscillators. It runs the oscillator in both basic and third overtone at the same time. By measuring the beat frequency between the modes, the temperature can be measured. See the John Vig presentation http://www.am1.us/Papers/U11625 VIG-TUTORIAL.PDF starting at page 43. I see no reason why it could not be used to stabilize the temperature. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
A hint for using peltiers, the resistive component in them has a problem with IsquaredR heating so that better performance is obtained by running them on filtered DC. PWM control works best if it is filtered to DC. My choice for temperature control is a glass encapsulated thermistor, there are some quite small ones that have very fast response and good ageing performance. Diodes and transdiodes also make good sensors and can come in good packages with rapid response. For us the best temperature standard is ice point and that is only good to 10 mK. Anything better means a trip to a standards laboratory. However, one is to be applauded for trying to link temperature to frequency, cheers, Neville Michie On 09/11/2010, at 2:04 AM, Poul-Henning Kamp wrote: I'm contemplating building a small temperature control enclosure for testing various electronics. I have a handful of peltiers suitable for the purpose, and was pondering the right control mechanism. Most people would reach for a NTC, put it in a wien-brige etc etc. But since I happen to have access to much more stable frequencies than voltages, I thought of a different way: 1. Mount a X-tal-osc with really lousy tempco inside the enclosure. 2. Compare its output to a stable reference frequency. 3. Use the output of the phase comparator to drive the Peltier. It is basically a PLL where temperature is used as EFC... Has anybody tried that ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/ time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
Hi Actually a primary temperature standard (triple point cell) is about the cheapest primary standard you can buy these days. A very good one (~ 0.1 mK) is still in the $1K range. If you are ok with basic glass work (or know somebody who is) you can make a quite adequate one (~1 mK) for sub $100. If only you could build your own Cesium standard for $100 ... Bob On Nov 8, 2010, at 7:45 PM, Neville Michie wrote: A hint for using peltiers, the resistive component in them has a problem with IsquaredR heating so that better performance is obtained by running them on filtered DC. PWM control works best if it is filtered to DC. My choice for temperature control is a glass encapsulated thermistor, there are some quite small ones that have very fast response and good ageing performance. Diodes and transdiodes also make good sensors and can come in good packages with rapid response. For us the best temperature standard is ice point and that is only good to 10 mK. Anything better means a trip to a standards laboratory. However, one is to be applauded for trying to link temperature to frequency, cheers, Neville Michie On 09/11/2010, at 2:04 AM, Poul-Henning Kamp wrote: I'm contemplating building a small temperature control enclosure for testing various electronics. I have a handful of peltiers suitable for the purpose, and was pondering the right control mechanism. Most people would reach for a NTC, put it in a wien-brige etc etc. But since I happen to have access to much more stable frequencies than voltages, I thought of a different way: 1. Mount a X-tal-osc with really lousy tempco inside the enclosure. 2. Compare its output to a stable reference frequency. 3. Use the output of the phase comparator to drive the Peltier. It is basically a PLL where temperature is used as EFC... Has anybody tried that ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
Javier Herrero wrote: Hi, Why not use a more conventional approach using a good thermistor and a PWM IC? I built some in the past with Peltiers and an LM3524 for cooling a photomultiplier in a nitrogen oxyde analyzer, and the result was quite good. I also used the same approach (but not with Peltier) for heating. Of course, the frequency stability was not time-nuts grade... not even near :) NTCs like the YSI 44031 have very good repeatabilty, and the resistance vs. temperature curve is quite steep, so you really don't need too stringent voltage stability needs. or for more precision/linearity what about a platinum resistance thermometer (PRT)... ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency referenced temperature regulator
On 11/09/2010 12:51 AM, Bob Camp wrote: Hi You can do very much the same thing by getting an SC to run on both the B and C modes at the same time. Hmm. Yes, but filtering will be a bit more trickier? Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
