Re: [time-nuts] Environmental sensor recommendations

[Bob kb8tq]

Hi

Just to be very clear about this issue:

Your room temperature “moves” at a rate dimensioned in degrees / hour (like
2 degrees / hour) and the period should be out in the half hour to couple of 
hours range. Put another way, it’s a 1,800 to > 5,000 second sort of thing. 

Operating with typical loop parameters, a TBolt is locked to GPS past a few 
hundred seconds. The OCXO simply follows whatever the GPS happens to
suggest is correct. The temperature effects (whatever the source) are past
the GPS cutover point. 

Unless you are running the TBolt into something other than an OCXO, the 
loop will take out *any* of the temperature impacts on the output of the 
device. 
That’s just the way a control loop works. It’s how it was designed to work. It
also is (most likely) why none of this bothered the original design team. 

In holdover, you will see / do see / can see the impact of temperature. The
gotcha there is that the TBolt has a temperature sensor on it. In holdover 
that sensor “corrects” the EFC voltage. To the degree this process works, 
it takes out any temperature impact in holdover. Again, it’s probably why 
the original design team felt things were ok.

So, why when you change this or that (like to a different OCXO) does the 
temperature sensitivity plot change? Well, if the DAC / reference is the source
of the error *and* you reduce the sensitivity of the OCXO, the temperature
impact *is* reduced. Go to something like a normal 10811 with a 1x10^7 etc
range and the impact should go down by more than an order of magnitude. 
LH is *not* lying to you…..

What is a problem: You look at the plot on LH and conclude that the TBolt
is wandering around with temperature changes. That’s not what it’s telling you.
The only thing LH *can* observe with just a TBolt are variations that have 
been corrected for by the control loop. If the loop does not correct for them,
the DAC does not change, and LH has nothing to go on. With no data
to indicate a change, LH reports that nothing has happened. Again it’s not
lying to you. It simply can only do just so much with the information it has. 

None of this is to say that the various effects are un-interesting. They are 
fun to watch. What would be more interesting would be to be able to dig
a bit deeper. We already can go a lot further into a TBolt than any of the 
other commercial units. Complaining that we can’t go further is … well …
this is TimeNuts …. 

Bob

> On Apr 6, 2018, at 8:30 AM, ew via time-nuts  wrote:
> 
> How did you measure temperature sensitivity
> Bert Kehren
>  
> In a message dated 4/6/2018 3:40:18 AM Eastern Standard Time, 
> hol...@hotmail.com writes:
> 
>  
> I replaced the OCXO on one of my Thunderbolts with an Oscilloquartz 8663 and 
> the temperature sensitivity went down by about 2/3, so I always assumed the 
> main contributor was the OCXO. I didn't try mod-ing any other Tbolts. 
> 
> I also tried temperature stabilizing the power supply and it seemed to also 
> have an influence.
> 
> -
> 
>> I respectfully disagree. The OCXO is not the temperature problem with the 
>> Tbolt.
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Re: [time-nuts] Environmental sensor recommendations

[Bob kb8tq]

Hi

Since the DAC is integrated into the *guts* (FPGA) on the board, there really 
isn’t a way to
pull it out. There *might* be a way to feed it a better reference (which likely 
is the bigger 
issue). Since there are no schematics for a TBolt there’s not much of a way to 
do this or that.
If you *did* put in a new DAC, you would need to re-write the firmware to match 
up with that
part. Again you hit the same wall. There are no copies of the firmware source 
code “in the wild”.
You would have to figure out how to dump and reverse assemble the code that’s 
in there. 

Bottom line - since it’s a GPSDO and locked all the time …. not a big deal. If 
you used it in 
holdover, then it might be a big deal.

Bob

> On Apr 6, 2018, at 12:40 AM, David C. Partridge 
> <david.partri...@perdrix.co.uk> wrote:
> 
>> The OCXO is not the temperature problem with the Tbolt. It is the DAC.
> 
> So is there a better one that can be used to replace it?
> 
> David
> 
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of ew via 
> time-nuts
> Sent: 05 April 2018 10:43
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] Environmental sensor recommendations
> 
> I respectfully disagree. The OCXO is not the temperature problem with the 
> Tbolt. It is the DAC. Again this is not a product developed for time nuts it 
> did an excellent job for its intended purpose. Over a year we worked on the 
> Tbolt using HP 10811, OSA 8600, FRK Rb, M100 Rb with excellent Warren support.
> Using up to 40 000 seconds and 6 E-17 per uV we probably know more about the 
> Tbolt than any time nut. The DAC on the Tbolt is worse than 1 E-10, we have 
> experimented with temperature control of the board. As a matter of fact the 
> OCXO contributes to a certain amount of temperate stability.
> Attila visited Juerg and me on my Europe trip and observed 3 Tbolt's, 
> original, 8600 and M100 in operation. Tracor 527 showed the jumps of the 
> original.
> We plan on using the OCXO's pulled as offset OCXO's on our latest D/M project.
> Bert Kehren 
> 
> In a message dated 4/4/2018 11:46:09 PM Eastern Standard Time, 
> hol...@hotmail.com writes:
> 
> 
> Lady Heather has a very nice temperature control PID in it (designed by 
> Warren Sarkisen). It was originally designed to stabilize the temperature of 
> a Thunderbolt GPSDO. The standard Thunderbolt OCXO is rather temperature 
> sensitive. 
> 
> The standard/simple implementation involves sticking the Thunderbolt in a 
> cardboard box with some thermal mass and baffling. Heather then PWMs a fan 
> (at 1 Hz, using the serial port modem control signals and a DC solid state 
> relay) to mix room temperature air into the box. It can control the 
> temperature readings to around 0.01C with long term RMS errors in the low 
> microdegree range (absolute accuracy depends upon the temp sensor).
> 
> ---
> 
>> I would suggest that if you are looking at taking temperature sensor 
>> data
> and attempting to control some type of heating/cooling device that you 
> implement a PID loop for stability.
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Re: [time-nuts] Environmental sensor recommendations

[ew via time-nuts]

How did you measure temperature sensitivity
Bert Kehren
 
In a message dated 4/6/2018 3:40:18 AM Eastern Standard Time, 
hol...@hotmail.com writes:

 
 I replaced the OCXO on one of my Thunderbolts with an Oscilloquartz 8663 and 
the temperature sensitivity went down by about 2/3, so I always assumed the 
main contributor was the OCXO. I didn't try mod-ing any other Tbolts. 

I also tried temperature stabilizing the power supply and it seemed to also 
have an influence.

-

> I respectfully disagree. The OCXO is not the temperature problem with the 
> Tbolt.
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Re: [time-nuts] Environmental sensor recommendations

[David C. Partridge]

> The OCXO is not the temperature problem with the Tbolt. It is the DAC.

So is there a better one that can be used to replace it?

David

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of ew via 
time-nuts
Sent: 05 April 2018 10:43
To: time-nuts@febo.com
Subject: Re: [time-nuts] Environmental sensor recommendations

I respectfully disagree. The OCXO is not the temperature problem with the 
Tbolt. It is the DAC. Again this is not a product developed for time nuts it 
did an excellent job for its intended purpose. Over a year we worked on the 
Tbolt using HP 10811, OSA 8600, FRK Rb, M100 Rb with excellent Warren support.
Using up to 40 000 seconds and 6 E-17 per uV we probably know more about the 
Tbolt than any time nut. The DAC on the Tbolt is worse than 1 E-10, we have 
experimented with temperature control of the board. As a matter of fact the 
OCXO contributes to a certain amount of temperate stability.
Attila visited Juerg and me on my Europe trip and observed 3 Tbolt's, original, 
8600 and M100 in operation. Tracor 527 showed the jumps of the original.
We plan on using the OCXO's pulled as offset OCXO's on our latest D/M project.
Bert Kehren 
 
In a message dated 4/4/2018 11:46:09 PM Eastern Standard Time, 
hol...@hotmail.com writes:

 
 Lady Heather has a very nice temperature control PID in it (designed by Warren 
Sarkisen). It was originally designed to stabilize the temperature of a 
Thunderbolt GPSDO. The standard Thunderbolt OCXO is rather temperature 
sensitive. 

The standard/simple implementation involves sticking the Thunderbolt in a 
cardboard box with some thermal mass and baffling. Heather then PWMs a fan (at 
1 Hz, using the serial port modem control signals and a DC solid state relay) 
to mix room temperature air into the box. It can control the temperature 
readings to around 0.01C with long term RMS errors in the low microdegree range 
(absolute accuracy depends upon the temp sensor).

---

> I would suggest that if you are looking at taking temperature sensor 
> data
and attempting to control some type of heating/cooling device that you 
implement a PID loop for stability.
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Re: [time-nuts] Environmental sensor recommendations

[Jim Harman]

I would like to put in a good word for the DS18B20 temperature sensor. It
consumes very little power, uses the "1-Wire" protocol, and is available
pre-wired in a variety of configurations, for example this
https://www.adafruit.com/product/381
and this
https://www.adafruit.com/product/642

resolution is 12 bits, .0625 C, range -55 to +125 C.

You can connect a bunch of them in parallel on the same data pin if you
want to measure temperature at different locations

There is a pretty good 1-wire library for the Arduino.

On Thu, Apr 5, 2018 at 7:19 PM, Mark Sims  wrote:

> Digital temperature sensors have some advantages (like nice factory
> calibration),  but also so issues.   The IIC/SPI ones need to be mounted to
> a PCB and also have quite a bit of thermal mass.  They also need 4-6 wire
> cables.  They are hard to attach directly to a point that you want to
> monitor.
>
> The advantage of thermistors is that they are small,  cheap, readily
> available with leads attached, and only require a two wire cable.   You can
> easily tape them to whatever point you want to monitor.
>
> The ADT7420 is $8 a pop + PCB + assembly + cable.  Decent thermistors can
> be had for less than a buck.
>
> --
>
> >  Check out ADT7420:
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-- 

--Jim Harman
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Re: [time-nuts] Environmental sensor recommendations

[Tom Van Baak]

> Are there any recommendations for other off-the-shelf sensors worth looking 
> at?

Mark,

Check out ADT7420:
http://www.analog.com/media/en/technical-documentation/data-sheets/ADT7420.pdf

A useful white paper, including comparison of NTC RTD and IC sensors:
http://www.analog.com/media/en/technical-documentation/frequently-asked-questions/ADT7320_ADT7420_FAQs.pdf

It's also available in a variety of small eval boards, including PMOD 
compatible PCB and flex boards:
https://store.digilentinc.com/pmod-tmp2-temperature-sensor/
http://www.analog.com/en/design-center/evaluation-hardware-and-software/evaluation-boards-kits/eval-adt7420.html

/tvb

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Re: [time-nuts] Environmental sensor recommendations.

[Neil]

I've used a few Pt100 RTDs over the years for gas flow temperature 
control in the 200-300C range.  At 0.385 ohms per K, the challenge of 
managing the noise is a lot tougher than a cheapo NTC thermistor, but I 
needed repeatability and stability. 
http://www.farnell.com/datasheets/2278399.pdf


I use a 4-wire Kelvin connection, with 1 mA current drive. £14 at 10-off

Neil


On 05/04/2018 16:27, Dr. David Kirkby wrote:


Keysights nano volt / micro ohm meter takes

https://www.keysight.com/en/pd-101296%3Aepsg%3Apro-pn-34420A/micro-ohm-meter?cc=ZA=eng

can do direct SPRT, RTD, Thermistor, and Thermocouple measurements

SPRT = Standard Platinum Resistance Thermometer

I don't claim to know much about this, but the uncertainty quoted for the
SPRT probes with that meter is 0.003 deg C.

When I Google SPRT probes, I see they are incredibly expensive - many
thousands of USD each.

I'm a bit puzzled there seem to be a number of 3-wire platinum resistance
thermometers. I can understand using 4-wires for a Kelvin connection, but
can't understand the use of 3-wires.

Of course, for environmental monitor in a lab, one is most unlikely to need
very high accuracy.

Dave
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Re: [time-nuts] Environmental sensor recommendations

[ew via time-nuts]

I respectfully disagree. The OCXO is not the temperature problem with the 
Tbolt. It is the DAC. Again this is not a product developed for time nuts it 
did an excellent job for its intended purpose. Over a year we worked on the 
Tbolt using HP 10811, OSA 8600, FRK Rb, M100 Rb with excellent Warren support.
Using up to 40 000 seconds and 6 E-17 per uV we probably know more about the 
Tbolt than any time nut. The DAC on the Tbolt is worse than 1 E-10, we have 
experimented with temperature control of the board. As a matter of fact the 
OCXO contributes to a certain amount of temperate stability.
Attila visited Juerg and me on my Europe trip and observed 3 Tbolt's, original, 
8600 and M100 in operation. Tracor 527 showed the jumps of the original.
We plan on using the OCXO's pulled as offset OCXO's on our latest D/M project.
Bert Kehren 
 
In a message dated 4/4/2018 11:46:09 PM Eastern Standard Time, 
hol...@hotmail.com writes:

 
 Lady Heather has a very nice temperature control PID in it (designed by Warren 
Sarkisen). It was originally designed to stabilize the temperature of a 
Thunderbolt GPSDO. The standard Thunderbolt OCXO is rather temperature 
sensitive. 

The standard/simple implementation involves sticking the Thunderbolt in a 
cardboard box with some thermal mass and baffling. Heather then PWMs a fan (at 
1 Hz, using the serial port modem control signals and a DC solid state relay) 
to mix room temperature air into the box. It can control the temperature 
readings to around 0.01C with long term RMS errors in the low microdegree range 
(absolute accuracy depends upon the temp sensor).

---

> I would suggest that if you are looking at taking temperature sensor data
and attempting to control some type of heating/cooling device that you
implement a PID loop for stability.
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Re: [time-nuts] Environmental sensor recommendations

[Gary E. Miller]

Mark!

On Thu, 5 Apr 2018 07:13:49 +
Mark Sims  wrote:

> I looked at the TEMPer devices, but almost all of them seem to be HID
> devices that emulate a digi-monkey typing on a keyboard...

NTPsec uses them in a polled mode.  Very easy to work with.

# temper-poll -c
22.1

Python code to do it all here:

https://github.com/padelt/temper-python

You can get a TEMPer pretty cheap if you order directly from China.

> an emulate a serial port. 

I find that a negative.

> it costs more than the dogtaian USB-PA that also does pressure.

You're looking at list prices, they are a lot cheaper on ebay.  But
yes, pressure is nice to have.  Next time I need a sensor I'll
try the USB-PA.

RGDS
GARY
---
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588

Veritas liberabit vos. -- Quid est veritas?
"If you can’t measure it, you can’t improve it." - Lord Kelvin
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Re: [time-nuts] Environmental sensor recommendations

[Mark Goldberg]

I will comment on a couple postings:

On Wed, Apr 4, 2018 at 8:00 PM, Tisha Hayes  wrote:
>
> I would suggest that if you are looking at taking temperature sensor data
> and attempting to control some type of heating/cooling device that you
> implement a PID loop for stability.

I have implemented a PID controller with PWM output for a Peltier Cooler
for what is basically an oven to test TCXO boards. Performance is pretty
good, holding the temperature to within tenths of a degree.
I tend to connect sensors or sensor boards to an Arduino and output data to
and take commands from the serial port. The Arduino does the "real time"
stuff and the fancier stuff is implemented on a PC.


On Thu, Apr 5, 2018 at 6:20 AM, Bob kb8tq  wrote:
>Hi
>
>If you want something that is pre-calibrated, then the IC based parts are
the way to go.

I have used thermocouples with MAX31855 thermocouple interface boards and
also have used DS18B20s, which are quite interesting "IC" parts. You can
connect several in parallel, and they use the "One Wire" protocol, easy to
implement, saving wires. The problem with them is there are lots of
counterfeits out there. I bought them from a random supplier and they did
not work correctly. I contacted the manufacturer and they confirmed they
never made any with the date code that was printed on them. I bought some
from Digikey and they looked different and worked fine. Luckily I was able
to return the bad ones.

Regards,

Mark
W7MLG
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Re: [time-nuts] Environmental sensor recommendations.

[Dan Kemppainen]

Hi John,

Thermocouples are very robust, and have a very wide operating range.

However they require extremely accurate voltage measurements to get to 
sub degree temperature accuracy. On top of that they require a local 
temperature sensor to measure the 'reference' temperature (Or an actual 
Icepoint bath). Once you have those that a lookup table or up to 14th or 
so order polynomials (Depending on thermocouple, and range) is required 
to convert the 'reference temperature' and millivolt reading to the 
temperature measured.


Look at some of the NIST copies of the ITS-90 thermocouple tables and 
coefficients:

https://srdata.nist.gov/its90/download/download.html
https://srdata.nist.gov/its90/download/allcoeff.tab

Overall, a lot of things going on there with errors that all stack up 
(including silly things like not enough range in floating point number 
routines for polynomial calculations). Don't get me wrong, they make 
great sensors. Probably not the right sensor for a small home brew board.


IC Temp sensors, thermistors, or RTD's may all be reasonable options 
here. IC Temp sensors for simplicity, RTD's for accuracy, and 
thermistors (except where they are in a loop, holding the temp constant) 
for cost.



Dan



On 4/5/2018 12:00 PM, time-nuts-requ...@febo.com wrote:

Message: 11
Date: Thu, 5 Apr 2018 09:44:48 -0500
From: John Green<wpxs...@gmail.com>
To:time-nuts@febo.com
Subject: Re: [time-nuts] Environmental sensor recommendations.
Message-ID:
<cagrb8tlmgxhowoqsgxpg2c2xe8skxnqk1y9_chkmjwmikec...@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"

Why has no one mentioned thermocouples?
I had some experience with thermistors a few years back designing thermal
attenuators and equalizers for CATV. NTC thermistors can have a large
change of resistance for a unit change in temperature. They aren't linear,
but there are formulas for computing resistance vs temp. PTC thermistors
have a much smaller change per unit change in temp., but are much more
linear. And, they are susceptible to self heating, which makes things
interesting. If I remember correctly, in my research something called an
RTD was supposed to be the king when it came to accuracy and repeatability.
As someone else has stated, the IC devices are supposed to be quite good,
but you have to interface with them.

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Re: [time-nuts] Environmental sensor recommendations.

[Bob kb8tq]

Hi

Thermocouples are *really* low output voltage devices at “normal” temperatures.
That gets you in to fairly fancy measurement setups ( no “just strap it to an 
ADC 
input” stuff). They also require cold junction compensation. They measure 
offset 
temperature to that junction. You do a lot of work to get just one sensor to 
operate.
That can be done with various chips from various outfits. It’s still not cheap. 
The 
net result is no more accurate or higher resolution than the other stuff we 
have 
discussed. The place thermocouples come in are for very high or very low 
temperatures.
If you want to know if it’s really 2,876C, a thermistor is not what you want to 
use.

RTD’s are indeed very stable long term. Properly handled they can do a real 
good 
job. They are basically a strain gauge. Mount them wrong (yes, I have a few 
hundred
examples of this) or treat them wrong ….. they don’t do quite as well. If you 
really
want to get accuracy out of them, you run a triple point cell to calibrate them 
before
use. Yes, this is getting off into temperature nuts territory. 

Heading back a bit to the original question: 

What *does* impact your frequency or time standard? 

1) Temperature 
2) Pressure
3) Humidity
4) Load
5) Supply voltage
6) Acceleration (gravity)
7) Stress / strain (bending)
8) Time ( aging )
9) EMI ( injection locking )

I suppose that list could go on for quite a ways. The obvious one on the list 
that
has not been addressed yet is voltage. 

Bob

> On Apr 5, 2018, at 10:44 AM, John Green  wrote:
> 
> Why has no one mentioned thermocouples?
> I had some experience with thermistors a few years back designing thermal
> attenuators and equalizers for CATV. NTC thermistors can have a large
> change of resistance for a unit change in temperature. They aren't linear,
> but there are formulas for computing resistance vs temp. PTC thermistors
> have a much smaller change per unit change in temp., but are much more
> linear. And, they are susceptible to self heating, which makes things
> interesting. If I remember correctly, in my research something called an
> RTD was supposed to be the king when it came to accuracy and repeatability.
> As someone else has stated, the IC devices are supposed to be quite good,
> but you have to interface with them.
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Re: [time-nuts] Environmental sensor recommendations.

[Dr. David Kirkby]

On 5 April 2018 at 15:44, John Green  wrote:

> Why has no one mentioned thermocouples?
> I had some experience with thermistors a few years back designing thermal
> attenuators and equalizers for CATV. NTC thermistors can have a large
> change of resistance for a unit change in temperature. They aren't linear,
> but there are formulas for computing resistance vs temp. PTC thermistors
> have a much smaller change per unit change in temp., but are much more
> linear. And, they are susceptible to self heating, which makes things
> interesting. If I remember correctly, in my research something called an
> RTD was supposed to be the king when it came to accuracy and repeatability.
> As someone else has stated, the IC devices are supposed to be quite good,
> but you have to interface with them.
>


Keysights nano volt / micro ohm meter takes

https://www.keysight.com/en/pd-101296%3Aepsg%3Apro-pn-34420A/micro-ohm-meter?cc=ZA=eng

can do direct SPRT, RTD, Thermistor, and Thermocouple measurements

SPRT = Standard Platinum Resistance Thermometer

I don't claim to know much about this, but the uncertainty quoted for the
SPRT probes with that meter is 0.003 deg C.

When I Google SPRT probes, I see they are incredibly expensive - many
thousands of USD each.

I'm a bit puzzled there seem to be a number of 3-wire platinum resistance
thermometers. I can understand using 4-wires for a Kelvin connection, but
can't understand the use of 3-wires.

Of course, for environmental monitor in a lab, one is most unlikely to need
very high accuracy.

Dave
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Re: [time-nuts] Environmental sensor recommendations

[Bob kb8tq]

HI

Quite true. 

The down side is that I can buy a bag of 100 parts that are +/- 0.25 C at 25C 
for a lower delivered 
price as one piece of the calibrated parts.  It’s a lot easier to glue down and 
throw away the cheap ones ….

Bob

> On Apr 5, 2018, at 10:15 AM, Edesio Costa e Silva  
> wrote:
> 
> If you use an "interchangeable" NTC like
> https://br.mouser.com/ProductDetail/US-Sensor/PS103J2 you can skip the
> calibration part.
> 
> Edésio
> 
> On Thu, Apr 05, 2018 at 09:20:56AM -0400, Bob kb8tq wrote:
>> Hi
>> 
>> By far the highest resolution sensor you will come across is a thermistor. 
>> It also has a pretty
>> narrow range in terms of maintaining high resolution. That???s fine for 
>> something with a target
>> temperature ( OCXO oven) and not so fine for monitoring outdoor temperature 
>> year round.
>> 
>> If you want something that is pre-calibrated, then the IC based parts are 
>> the way to go. They
>> are a much better answer to the ???general purpose sensor question. 
>> Mounting them and hooking
>> up to them ??? errr ???. not quite so easy.
>> 
>> One basic answer is to buy a bag of cheap thermistors and calibrate them 
>> yourself. They may
>> have odd curves, but so far the entire bag looks about the same. That???s 
>> been true for a couple
>> of bags bought randomly here and there. For a lot of things, a simple three 
>> point calibration will
>> do pretty well. You still need to do a rational curve fit, but even that 
>> isn???t to crazy over limited
>> ranges.
>> 
>> Bob
>> 
>>> On Apr 4, 2018, at 8:58 PM, Mark Sims  wrote:
>>> 
>>> I recently (mostly)  finished adding external environmental sensor support 
>>> to Lady Heather.   You can use the sensor as the primary "receiver" device 
>>> or in conjunction with any of the "receivers" that Lady Heather supports 
>>> (except currently the HP-5071A which uses the same plot queue entries as 
>>> the environmental sensors).  Heather supports humidity, pressure, and two 
>>> temperature values.
>>> 
>>> I am currently using a dogratian.com USB-PA sensor with temperature, 
>>> humidity, and pressure.  I am also designing a Heather specific board 
>>> (BME280, two thernistors, temperature controller interface, maybe a couple 
>>> of ADC channels, etc).   Are there any recommendations for other 
>>> off-the-shelf sensors worth looking at?
>>> 
>>> The main requirement is that the sensor should send data over a serial port 
>>> or virtual serial port or maybe ethernet.   Ideally it would stream 
>>> readings at 1 Hz, but a polled device (like the dogratian.com devices) can 
>>> be accomodated.Also, it would be very nice if the temperature sensors 
>>> are small, responsive, and on leads that could be attached to whatever is 
>>> being monitored.
>>> 
>>> Attached is a screen dump of the USB-PA running.   Can you spot the furnace 
>>> cycling and sunrise?
>>> ___
>>> 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.
>> 
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Re: [time-nuts] Environmental sensor recommendations.

[John Green]

Why has no one mentioned thermocouples?
I had some experience with thermistors a few years back designing thermal
attenuators and equalizers for CATV. NTC thermistors can have a large
change of resistance for a unit change in temperature. They aren't linear,
but there are formulas for computing resistance vs temp. PTC thermistors
have a much smaller change per unit change in temp., but are much more
linear. And, they are susceptible to self heating, which makes things
interesting. If I remember correctly, in my research something called an
RTD was supposed to be the king when it came to accuracy and repeatability.
As someone else has stated, the IC devices are supposed to be quite good,
but you have to interface with them.
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Re: [time-nuts] Environmental sensor recommendations

[Edesio Costa e Silva]

If you use an "interchangeable" NTC like
https://br.mouser.com/ProductDetail/US-Sensor/PS103J2 you can skip the
calibration part.

Edésio

On Thu, Apr 05, 2018 at 09:20:56AM -0400, Bob kb8tq wrote:
> Hi
>
> By far the highest resolution sensor you will come across is a thermistor. It 
> also has a pretty
> narrow range in terms of maintaining high resolution. That???s fine for 
> something with a target
> temperature ( OCXO oven) and not so fine for monitoring outdoor temperature 
> year round.
>
> If you want something that is pre-calibrated, then the IC based parts are the 
> way to go. They
> are a much better answer to the ???general purpose sensor question. 
> Mounting them and hooking
> up to them ??? errr ???. not quite so easy.
>
> One basic answer is to buy a bag of cheap thermistors and calibrate them 
> yourself. They may
> have odd curves, but so far the entire bag looks about the same. That???s 
> been true for a couple
> of bags bought randomly here and there. For a lot of things, a simple three 
> point calibration will
> do pretty well. You still need to do a rational curve fit, but even that 
> isn???t to crazy over limited
> ranges.
>
> Bob
>
> > On Apr 4, 2018, at 8:58 PM, Mark Sims  wrote:
> >
> > I recently (mostly)  finished adding external environmental sensor support 
> > to Lady Heather.   You can use the sensor as the primary "receiver" device 
> > or in conjunction with any of the "receivers" that Lady Heather supports 
> > (except currently the HP-5071A which uses the same plot queue entries as 
> > the environmental sensors).  Heather supports humidity, pressure, and two 
> > temperature values.
> >
> > I am currently using a dogratian.com USB-PA sensor with temperature, 
> > humidity, and pressure.  I am also designing a Heather specific board 
> > (BME280, two thernistors, temperature controller interface, maybe a couple 
> > of ADC channels, etc).   Are there any recommendations for other 
> > off-the-shelf sensors worth looking at?
> >
> > The main requirement is that the sensor should send data over a serial port 
> > or virtual serial port or maybe ethernet.   Ideally it would stream 
> > readings at 1 Hz, but a polled device (like the dogratian.com devices) can 
> > be accomodated.Also, it would be very nice if the temperature sensors 
> > are small, responsive, and on leads that could be attached to whatever is 
> > being monitored.
> >
> > Attached is a screen dump of the USB-PA running.   Can you spot the furnace 
> > cycling and sunrise?
> > ___
> > 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.
>
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Re: [time-nuts] Environmental sensor recommendations

[Tom Van Baak]

Peter,

Yes, that's my current favorite turn-key environmental sensor as well. Sure, 
you can home-brew a slightly cheaper solution. And the Arduino world is full of 
random sensor examples, which you are free to deploy and debug. But the 
Sparkfun unit just works; out of the box. From the first second after power-up, 
and once every second after that, it does the one thing it is designed for: 
sense and report.

Their model is serial (USB) ascii output once a second. This works: without 
API, without command / response, without tie-in to a particular operating 
system, or driver, or downloads, or app, or API, or language du jour, or login, 
or encryption, or cloud. It's how digital sensors should be designed. KISS.

This is also why so many of us like the hp 53131A / 53132A talk-only mode. It 
just measures and reports. The picPET and TAPR TICC were designed the same way.

/tvb

- Original Message - 
From: "Peter Vince" <petervince1...@gmail.com>
To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com>
Sent: Thursday, April 05, 2018 6:24 AM
Subject: Re: [time-nuts] Environmental sensor recommendations


> Hi Mark,
> 
> SparkFun have some boards that have multiple sensors.  They *used* to
> do one with a USB connection that had temperature, pressure, humidity, and
> light!  But I see that is now "retired" (
> https://www.sparkfun.com/products/retired/8311 ) and has been replaced by
> an Arduino shield:
> 
> https://www.sparkfun.com/products/13956
> 
> The previous USB model was very easy to use, and sensitive enough for
> pressure that it easily showed when I walked up a couple of flights of
> stairs!  They have a large selection of boards, including several with I2C
> connections, so maybe one of those would be suitable?
> 
> TTFN,
> 
>  Peter

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Re: [time-nuts] Environmental sensor recommendations

[Bob kb8tq]

Hi

By far the highest resolution sensor you will come across is a thermistor. It 
also has a pretty 
narrow range in terms of maintaining high resolution. That’s fine for something 
with a target
temperature ( OCXO oven) and not so fine for monitoring outdoor temperature 
year round. 

If you want something that is pre-calibrated, then the IC based parts are the 
way to go. They
are a much better answer to the “general purpose sensor?” question. Mounting 
them and hooking
up to them … errr …. not quite so easy. 

One basic answer is to buy a bag of cheap thermistors and calibrate them 
yourself. They may
have odd curves, but so far the entire bag looks about the same. That’s been 
true for a couple
of bags bought randomly here and there. For a lot of things, a simple three 
point calibration will
do pretty well. You still need to do a rational curve fit, but even that isn’t 
to crazy over limited
ranges. 

Bob

> On Apr 4, 2018, at 8:58 PM, Mark Sims  wrote:
> 
> I recently (mostly)  finished adding external environmental sensor support to 
> Lady Heather.   You can use the sensor as the primary "receiver" device or in 
> conjunction with any of the "receivers" that Lady Heather supports (except 
> currently the HP-5071A which uses the same plot queue entries as the 
> environmental sensors).  Heather supports humidity, pressure, and two 
> temperature values.
> 
> I am currently using a dogratian.com USB-PA sensor with temperature, 
> humidity, and pressure.  I am also designing a Heather specific board 
> (BME280, two thernistors, temperature controller interface, maybe a couple of 
> ADC channels, etc).   Are there any recommendations for other off-the-shelf 
> sensors worth looking at?
> 
> The main requirement is that the sensor should send data over a serial port 
> or virtual serial port or maybe ethernet.   Ideally it would stream readings 
> at 1 Hz, but a polled device (like the dogratian.com devices) can be 
> accomodated.Also, it would be very nice if the temperature sensors are 
> small, responsive, and on leads that could be attached to whatever is being 
> monitored.
> 
> Attached is a screen dump of the USB-PA running.   Can you spot the furnace 
> cycling and sunrise?
> ___
> 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.

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Re: [time-nuts] Environmental sensor recommendations

[Peter Vince]

Hi Mark,

 SparkFun have some boards that have multiple sensors.  They *used* to
do one with a USB connection that had temperature, pressure, humidity, and
light!  But I see that is now "retired" (
https://www.sparkfun.com/products/retired/8311 ) and has been replaced by
an Arduino shield:

 https://www.sparkfun.com/products/13956

The previous USB model was very easy to use, and sensitive enough for
pressure that it easily showed when I walked up a couple of flights of
stairs!  They have a large selection of boards, including several with I2C
connections, so maybe one of those would be suitable?

 TTFN,

  Peter
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Re: [time-nuts] Environmental sensor recommendations

[Vlad]

Mark,

Thanks for doing this ! Aside of the "commercial" sensors, will you open 
the API or data format for the community ?
In such way, we could tailor our existed "telemetry devices" to be 
connected to LH ! I see lot of perspectives here. Seismic, radiation, 
lighting, main, air, light, gravity, you-name-it...


Regards,
Vlad

On 2018-04-04 20:58, Mark Sims wrote:

I recently (mostly)  finished adding external environmental sensor
support to Lady Heather.   You can use the sensor as the primary
"receiver" device or in conjunction with any of the "receivers" that
Lady Heather supports (except currently the HP-5071A which uses the
same plot queue entries as the environmental sensors).  Heather
supports humidity, pressure, and two temperature values.

I am currently using a dogratian.com USB-PA sensor with temperature,
humidity, and pressure.  I am also designing a Heather specific board
(BME280, two thernistors, temperature controller interface, maybe a
couple of ADC channels, etc).   Are there any recommendations for
other off-the-shelf sensors worth looking at?

The main requirement is that the sensor should send data over a serial
port or virtual serial port or maybe ethernet.   Ideally it would
stream readings at 1 Hz, but a polled device (like the dogratian.com
devices) can be accomodated.Also, it would be very nice if the
temperature sensors are small, responsive, and on leads that could be
attached to whatever is being monitored.

Attached is a screen dump of the USB-PA running.   Can you spot the
furnace cycling and sunrise?

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--
WBW,

V.P.
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Re: [time-nuts] Environmental sensor recommendations

[Hal Murray]

> Are there any recommendations for other off-the-shelf sensors=
>  worth looking at?

Consider the TEMPer USB units from eBay.  Their main advantage is low cost.  
They have a temperature sensor in a thumb drive size USB module.  At least 
one model comes with a slightly bulky sensor on the end of a 3ft cable.

Most of the low cost units have a fairly coarse step size.  Please let me/us 
know if you find (or build) a good high resolution setup.  I assume that will 
be a thermistor and good DAC.

-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Environmental sensor recommendations

[Gary E. Miller]

Yo Mark!

On Thu, 5 Apr 2018 00:58:50 +
Mark Sims  wrote:

> Are there any recommendations for
> other off-the-shelf sensors worth looking at?

I use several of the TEMPer series.  

http://pcsensor.com/usb-thermometer/temper1f.html

The TEMPer1F has a local and a remote temperature sensor.
The TEMPer1F_H1 has a remote etmperature/humidity sensor.
The basic TEMPerGold has one temp sensor, is the size of a thumbdrive
and costs under $10.

All easy to use.  Gotta be careful, a ton of slightly different
versions on the market.

RGDS
GARY
---
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588

Veritas liberabit vos. -- Quid est veritas?
"If you can’t measure it, you can’t improve it." - Lord Kelvin
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