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Surface temperature sensor

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longg(at)pjm.com
Guest

Posted: Wed Apr 21, 2010 9:46 am Post subject: Surface temperature sensor

Q,  

   

Has anyone come across an example of a surface temperature sensor (generic)) that could be used on engine parts or perhaps the firewall and send a digital reading back to the panel?   

   

Example. – I would like to measure the temperature on the surface of my oil filter/fuel pump and display that value on the panel.  

   

FYI – I have stick-on thermometers that work great when performing engine checks on the ground but they are of little use in the air.  

   

Thanks,  

   

Glenn  

   

   

      [quote][b]

rampil

Joined: 04 May 2007
Posts: 870

Posted: Wed Apr 21, 2010 12:10 pm Post subject: Re: Surface temperature sensor

Ahhhh,  how bout a thermocouple?  how bout a resistive probe like

many engines use for CHT.  This discussion group is replete with temp.

monitoring

_________________
Ira N224XS

longg(at)pjm.com
Guest

Posted: Wed Apr 21, 2010 1:04 pm Post subject: Surface temperature sensor

Do Not Archive



Thanks IRA,



Yes, I'll do some digging. I was thinking about something with a flat

profile and perhaps a stick on for a flat surface. There must be

somebody putting out a device that can be fastened to a flat surface

that has two wires sticking out of it.



Glenn



Do Not Archive



--

rampil

Joined: 04 May 2007
Posts: 870

Posted: Wed Apr 21, 2010 3:18 pm Post subject: Re: Surface temperature sensor

The actual sensors for t/c or thermistors are tiny inside those cans

they get mounted in. A tc is just two wires twisted in each other.

Either is easy to JB Weld in place on a surface

_________________
Ira N224XS

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Apr 21, 2010 9:58 pm Post subject: Surface temperature sensor

At 03:58 PM 4/21/2010, you wrote:

 	  Quote: 	
		  



Do Not Archive



Thanks IRA,



Yes, I'll do some digging. I was thinking about something with a flat

profile and perhaps a stick on for a flat surface. There must be

somebody putting out a device that can be fastened to a flat surface

that has two wires sticking out of it.


	


   We usually use a thermocouple wire and stick it to

   the surface with some epoxy. If you don't have

   a thermocouple reading instrument, you can rig

   a direct reading semiconductor sensor like the

   the LM285. It's powered up directly from your

   14v system through a 10K resistor and reads

   directly in degrees Kelvin. It's in the shape

   of a plastic TO92 transistor with a flat side

   easily bonded to the surface of interest.



   You can read it's measurement directly on

   a multimeter where 2.75 volts is equal to

   275 degrees K.



   Very handy for a quick-n-dirty look-see.



   Radio Shack and Harbor Freight both stock

   temperature reading multimeters based on

   type K thermocouple wire.



   Bob . . .

rv8iator

Joined: 11 Apr 2006
Posts: 145
Location: Newberg, OR

Posted: Thu Apr 22, 2010 5:54 am Post subject: Surface temperature sensor

Thermocouples are quite small.  I would think a piece of aluminum tape over the thermocouple onto the oil filter would get you a very accurate temp reading.



chris stone

[quote]

Do Not Archive



Thanks IRA,



Yes, I'll do some digging. I was thinking about something with a flat

profile and perhaps a stick on for a flat surface. There must be

somebody putting out a device that can be fastened to a flat surface

that has two wires sticking out of it.



Glenn



Do Not Archive



--

_________________
C. Stone (RV8iator)

longg(at)pjm.com
Guest

Posted: Thu Apr 22, 2010 5:56 am Post subject: Surface temperature sensor

Thanks all for the suggestions. Time to experiment.



Glenn



Do Not Archive.



--

deej(at)deej.net
Guest

Posted: Thu Apr 22, 2010 10:44 am Post subject: Surface temperature sensor

On 04/21/2010 01:42 PM, longg(at)pjm.com wrote:



 	  Quote: 	
		   Has anyone come across an example of a surface temperature sensor

 (generic)) that could be used on engine parts or perhaps the firewall

 and send a digital reading back to the panel?


	




	Tons of digital thermometers with remote wireless sensors are available

in Home and Garden sections of retail stores.



	Not a recommendation, but here is one example:

http://www.amazon.com/Crosse-Technology-Digital-Thermometer-Wireless/dp/B001DNIIOS/ref=sr_1_2?ie=UTF8&s=home-garden&qid=1271961133&sr=8-2

<http://www.amazon.com/Crosse-Technology-Digital-Thermometer-Wireless/dp/B001DNIIOS/ref=sr_1_2?ie=UTF8&s=home-garden&qid=1271961133&sr=8-2>



	Drop by your local Walmart, Home Depot, or Lowes and I'm sure you can

find plenty to choose from.



	Probably not too hard to tear apart the remote sensor housing and get

to the actual sensor itself to attach it directly to something.



-Dj



-- 

Dj Merrill - N1JOV

Glastar Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/

Grumman Yankee Driver N9870L - http://deej.net/yankee/

mcculleyja(at)starpower.n
Guest

Posted: Thu Apr 22, 2010 12:21 pm Post subject: Surface temperature sensor

I've been using a very inexpensive system with 18 sensor locations in my 

Wittman Tailwind for well over 500 hours and 7 years, with never a 

malfunction. It's based on inexpensive thermistors available from most 

electronics suppliers and feeds into the display head of an ordinary 

digital meat thermometer mounted on my instrument panel. It can handle 

up to 300 degree F which covers everything firewall-forward except 

engine cylinder EGT and CHT.



If you want some part numbers and more details contact me off list at 

mcculleyja(at)starpower.net.



Jim McCulley

=================================================================================== 

longg(at)pjm.com wrote:

 	  Quote: 	
		   

 

 Q,

 

  

 

 Has anyone come across an example of a surface temperature sensor 

 (generic)) that could be used on engine parts or perhaps the firewall 

 and send a digital reading back to the panel?

 

  

 

 Example. – I would like to measure the temperature on the surface of my 

 oil filter/fuel pump and display that value on the panel.

 

  

 

 FYI – I have stick-on thermometers that work great when performing 

 engine checks on the ground but they are of little use in the air.

 

  

 

 Thanks,

 

  

 

 Glenn

 

  

 

  

 

 * 

 

 

  *

lists(at)stevet.net
Guest

Posted: Fri Apr 23, 2010 5:08 am Post subject: Surface temperature sensor

Why off-list?  I'm sure that many readers of the list would be interested.  Please share with all of us!

Steve Thomas

________________________________________________________________________

On Apr 22, 2010, at 1:19 PM, J. Mcculley wrote:

 	  Quote: 	

 I've been using a very inexpensive system with 18 sensor locations in my Wittman Tailwind for well over 500 hours and 7 years, with never a malfunction. It's based on inexpensive thermistors available from most electronics suppliers and feeds into the display head of an ordinary digital meat thermometer mounted on my instrument panel. It can handle up to 300 degree F which covers everything firewall-forward except engine cylinder EGT and CHT.

 If you want some part numbers and more details contact me off list at mcculleyja(at)starpower.net.

 Jim McCulley

 =================================================================================== 

 longg(at)pjm.com wrote:

> Q,

> Has anyone come across an example of a surface temperature sensor (generic)) that could be used on engine parts or perhaps the firewall and send a digital reading back to the panel?

> Example. – I would like to measure the temperature on the surface of my oil filter/fuel pump and display that value on the panel.

> FYI – I have stick-on thermometers that work great when performing engine checks on the ground but they are of little use in the air.

> Thanks,

> Glenn

>  *  *

rampil

Joined: 04 May 2007
Posts: 870

Posted: Fri Apr 23, 2010 12:45 pm Post subject: Re: Surface temperature sensor

Don't count on home and garden type thermometer systems to be

especially accurate.  They have no requirement to be calibrated

or calibrateable.

_________________
Ira N224XS

deej(at)deej.net
Guest

Posted: Fri Apr 23, 2010 1:11 pm Post subject: Surface temperature sensor

On 4/23/2010 4:45 PM, rampil wrote:

 	  Quote: 	
		   

 

 Don't count on home and garden type thermometer systems to be

 especially accurate.  They have no requirement to be calibrated

 or calibrateable.


	




	Easy enough to test - put the sensor in boiling water.  If it is even

remotely close to the right value, it is probably "good enough" for most

of our purposes.  Hard to argue with the price...  



-Dj



-- 

Dj Merrill - N1JOV

Glastar Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/

Grumman Yankee Driver N9870L - http://deej.net/yankee/

mcculleyja(at)starpower.n
Guest

Posted: Fri Apr 23, 2010 6:41 pm Post subject: Surface temperature sensor

Sorry Steve and others...I just thought this subject might be of

interest to so few that I should not take up bandwith that those not 

interested would have to deal with. But, here it is:

This is a very accurate system that I tested with a laboratory quality

temperature meter and found the accuracy of all my sensors to be ± two

degrees F. It may not be very sophisticated, but it is super-inexpensive

and has never malfunctioned. I use it on every flight to assure myself

that no changes suddenly occur that could indicate a malfunction.



Mine is about a $15 to $25 system that I've operated now for over seven

years and upwards of 600 flight hours on it's original internal

watch-size battery.  The sensors are standard mini glass-encapsulated

thermistors available from most electronic supply sources. I used

Digi-Key # KC013-ND, 100k ohm units.



For those sensors measuring metal surface temperatures (cylinder bases,

starter, mags, boost pump, alternator, etc.) the sensors are attached to

the surfaces with heat sink grease, and held in place mechanically

and/or with a coating of the red 600 degree RTV, then insulated from

surrounding radiation with fireman's suit material. To assure firm

contact with the surface until the RTV sets requires some simple tricks

I won’t cover unless you desire later.



Those sensors that measure airflow temperatures are mechanically

supported in various ways depending upon the surrounding environment,

and are then shielded from nearby heat radiation, using standoff shields.



The display is a panel mounted single LCD with a compact surface mount

IC unit that I adapted from a meat thermometer with a range up to 300F.

The head of the meat thermometer becomes the panel mounted digital

display after cutting off the long stem, but retaining the internal pair

of wires to the display head.



The individual sensor locations are selected for readout through a

rotary switch on the panel. The delay in the presentation from one

sensor selection to the next is less than one second and my poor-man's

data recording system is via my hot mike through the intercom to a voice

recorder. In this current era of exotic digital commercial boxes for

anything a person desires, my "keep-it-simple and build-in-lightness

mentality" may not be the answer for others, but I don't mind

post-flight manually inputting the data from my recorder into a

spreadsheet for further massaging if needed.



The installation of the thermistors is simpler and much less expensive

than thermocouples and since the thermistors operate in a very

high-impedence circuit the wiring need not be any larger size than

needed to assure mechanical robustness. I used 22 gauge wire and joined

all the ground return wires together to pass through the firewall as a

single lead, so the wire bundle becomes very small aft of the firewall.

Also, because of the very high impedence of the circuitry, there is no

sensitivity to length of individual sensor wires between thermistor and

display for any possible location within a general aviation

installation. Good quality soldering technique is very adequate for

connections, as are properly-crimped-on terminals, if desired.

========================================================================



Steve Thomas wrote:

 	  Quote: 	
		   

 

 Why off-list? I'm sure that many readers of the list would be interested.


	


 	  Quote: 	
		   Please share with all of us!

 

 

 Steve Thomas

 ________________________________________________________________________

 

 

 

 

 On Apr 22, 2010, at 1:19 PM, J. Mcculley wrote:

 

> AeroElectric-List message posted by: "J. Mcculley" <mcculleyja(at)starpower.net>

> I've been using a very inexpensive system with 18 sensor locations in my 

> Wittman Tailwind for well over 500 hours and 7 years, with never a 

> malfunction. It's based on inexpensive thermistors available from most

> electronics suppliers and feeds into the display head of an ordinary 

> digital meat thermometer mounted on my instrument panel. It can handle 

> up to 300 degree F which covers everything firewall-forward except engine 

> cylinder EGT and CHT.

>

> If you want some part numbers and more details contact me off list at

> mcculleyja(at)starpower.net.

>

> Jim McCulley

> ========================================================================= 

>

> longg(at)pjm.com wrote:

>> Q,

>> Has anyone come across an example of a surface temperature sensor (generic))

 >>> that could be used on engine parts or perhaps the firewall and send 
	


a digital

 >>> reading back to the panel?

 	  Quote: 	
		  >> Example. – I would like to measure the temperature on the surface of my 

 >>> oil filter/fuel pump and display that value on the panel.
	


 	  Quote: 	
		  >> FYI – I have stick-on thermometers that work great when performing 

 >>> engine checks on the ground but they are of little use in the air.
	


 	  Quote: 	
		  >> Thanks,

>> Glenn

>>  *  *

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Apr 24, 2010 7:20 am Post subject: Surface temperature sensor

At 09:38 PM 4/23/2010, you wrote:

 	  Quote: 	
		  

Mcculley" <mcculleyja(at)starpower.net>



Sorry Steve and others...I just thought this subject might be of

interest to so few that I should not take up 

bandwith that those not interested would have to deal with. But, here it is:

This is a very accurate system that I tested with a laboratory quality

temperature meter and found the accuracy of all my sensors to be ± two

degrees F. It may not be very sophisticated, but it is super-inexpensive

and has never malfunctioned. I use it on every flight to assure myself

that no changes suddenly occur that could indicate a malfunction.



Mine is about a $15 to $25 system that I've operated now for over seven

years and upwards of 600 flight hours on it's original internal

watch-size battery.  The sensors are standard mini glass-encapsulated

thermistors available from most electronic supply sources. I used

Digi-Key # KC013-ND, 100k ohm units.


	


   How was it that you determined that the 100K devices were

   appropriate to your particular display? Folks should understand

   that there are hundreds of remote temperature measurement

   products on the market. I've see them use thermocouples, solid

   state LINEAR  temperature sensors, diodes, the junctions of

   transistors (also a diode) AND thermistors.



http://www.gesensing.com/products/resources/datasheets/ge1.pdf



   Thermistors are inexpensive AND rugged but they have the

   distinct disadvantage of being non-linear. So the accurate

   temperature display not only needs to know what the resistance

   of the device is at say 25C, the designer will compensate for

   the shape of temperature/resistance curve as well.



   The first thing one needs to do when adapting a commercial

   off the shelf (COTS) indicator to their airplane is to determine

   the sensor technology. If a thermistor, then you need to get

   the 25C resistance rating, and then the resistance at some

   other handy value (boiling water - 100C) and then find

   substitute sensors of identical characteristics.



   The really cool thing about the linear, solid state sensors

   is that they are direct reading, linear, and of known accuracy

   out of the box. I'm not discouraging anyone from exploring

   adaptation of any COTS temperature display but understand that

   there are some inviolate rules by which the sensing technology

   is identified and then duplicated so that the display performs

   as expected.



   Bob . . .

mcculleyja(at)starpower.n
Guest

Posted: Sat Apr 24, 2010 10:18 am Post subject: Surface temperature sensor

Using a laboratory quality temperature instrument I determined the 

readings (at about 10 degree F intervals) of a typical digital display 

meat thermometer (10-15 dollar variety some 10 years ago) and found the 

error varied well within +/- 3F within the range of interest I 

considered appropriate as about 70 to 300F for firewall-forward 

applications.



Then by carefully extracting the sensor inside the very tip of the meat 

thermometer, I compared it in size and appearance to a variety of 

commercially available thermistors and tested several by electrically 

substituting them in place of the original until finding the one I 

mentioned by source and part number to be apparently identical in 

performance over the same range of temperature interest.



After completing the installation in the aircraft, another test with the 

lab-quality meter for comparison gave the same ballpark results and also 

showed that with the nominal 100K resistance value stated for the 

thermistor, the total impedance of the completed installation for any 

likely difference in length of wiring between the closest versus 

greatest distance of sensors created no error even when wired with the 

smallest gauge wire I felt appropriate for use in an aircraft 

installation with heat and vibration considerations.



My assumption was/is that the surface mounted electronic circuitry in 

the meat thermometer display head performs the necessary compensation 

for non linear characteristics of the basic thermistor. Although I was 

unable to obtain any data from the thermometer vendor, I assume I was 

just lucky enough to perhaps have stumbled upon the exact same-source 

thermistor used in the retail unit.



Jim McCulley

=========================================================================================



Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   

 <nuckolls.bob(at)aeroelectric.com>

 

 At 09:38 PM 4/23/2010, you wrote:

> 

> <mcculleyja(at)starpower.net>

>

> Sorry Steve and others...I just thought this subject might be of

> interest to so few that I should not take up bandwith that those not 

> interested would have to deal with. But, here it is:

> This is a very accurate system that I tested with a laboratory quality

> temperature meter and found the accuracy of all my sensors to be ± two

> degrees F. It may not be very sophisticated, but it is super-inexpensive

> and has never malfunctioned. I use it on every flight to assure myself

> that no changes suddenly occur that could indicate a malfunction.

>

> Mine is about a $15 to $25 system that I've operated now for over seven

> years and upwards of 600 flight hours on it's original internal

> watch-size battery.  The sensors are standard mini glass-encapsulated

> thermistors available from most electronic supply sources. I used

> Digi-Key # KC013-ND, 100k ohm units.

 

   How was it that you determined that the 100K devices were

   appropriate to your particular display? Folks should understand

   that there are hundreds of remote temperature measurement

   products on the market. I've see them use thermocouples, solid

   state LINEAR  temperature sensors, diodes, the junctions of

   transistors (also a diode) AND thermistors.

 

 http://www.gesensing.com/products/resources/datasheets/ge1.pdf

 

   Thermistors are inexpensive AND rugged but they have the

   distinct disadvantage of being non-linear. So the accurate

   temperature display not only needs to know what the resistance

   of the device is at say 25C, the designer will compensate for

   the shape of temperature/resistance curve as well.

 

   The first thing one needs to do when adapting a commercial

   off the shelf (COTS) indicator to their airplane is to determine

   the sensor technology. If a thermistor, then you need to get

   the 25C resistance rating, and then the resistance at some

   other handy value (boiling water - 100C) and then find

   substitute sensors of identical characteristics.

 

   The really cool thing about the linear, solid state sensors

   is that they are direct reading, linear, and of known accuracy

   out of the box. I'm not discouraging anyone from exploring

   adaptation of any COTS temperature display but understand that

   there are some inviolate rules by which the sensing technology

   is identified and then duplicated so that the display performs

   as expected.

 

   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Apr 24, 2010 6:31 pm Post subject: Surface temperature sensor

 	  Quote: 	
		  Then by carefully extracting the sensor inside the very tip of the 

meat thermometer, I compared it in size and appearance to a variety 

of commercially available thermistors and tested several by 

electrically substituting them in place of the original until 

finding the one I mentioned by source and part number to be 

apparently identical in performance over the same range of 

temperature interest.


	


   Aha! Then there was a rational exercise to pick a

   thermistor that matched the operating characteristics

   of the device being cloned.



   This is the point that we needed to make clear

   to our readers. There are thousands of thermistor

   parts of which only a few will directly replace the

   sensor used in a randomly selected off the shelf

   thermometer.



I assume I was just lucky enough to perhaps have stumbled upon the 

exact same-source thermistor used in the retail unit.



   Don't know about 'luck'. You can measure the 25C

   resistance point for device under study. You could

   also measure it's resistance at say, two other points

   over the range of interest . . . like 0C (ice point)

   and 100C (boiling point). Then by studying the

   temperature/resistance transfer curves (or as you

   did, experimentation) you can find a match. Afterr

   that, you're home free.  As you've described, you

   can switch as many remote sensors in to the display

   as you like.



   The only thing I wanted to make clear was that

   unlike thermocouples and factory calibrated

   temperature sensors, thermistors are a breed

   unto themselves. The successful user will have

   to learn a few dditions to their back of

   electro-whizzy tricks.



   Thanks for sharing your experience in this

   discussion!



   Bob . . .

user9253

Joined: 28 Mar 2008
Posts: 1921
Location: Riley TWP Michigan

Posted: Sun Apr 25, 2010 5:32 am Post subject: Re: Surface temperature sensor

Jim McCulley,

Good job making an economical and accurate multi-point temperature sensor and indicator.  I admire your ingenuity and resourcefulness.

Joe

_________________
Joe Gores

mcculleyja(at)starpower.n
Guest

Posted: Sun Apr 25, 2010 9:48 am Post subject: Surface temperature sensor

Thanks, Joe, for the compliment! Hope you find the concept useful for 

your purposes.



Jim

=============================================================================================



user9253 wrote:

 	  Quote: 	
		   

 

 Jim McCulley,

 Good job making an economical and accurate multi-point temperature sensor and indicator.  I admire your ingenuity and resourcefulness.

 Joe

 

 --------

 Joe Gores

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=295622#295622

longg(at)pjm.com
Guest

Posted: Tue Apr 27, 2010 1:07 pm Post subject: Surface temperature sensor

I'll second that - Jim, thanks for the due diligence. I'm not that

creative at this point so I found a relatively low cost source for a 4

channel display which supports standard thermocouples and can also be

panel mounted. While not their main business, these folks seem keen

towards supplying the aircraft market. http://www.omega.com is sort of a

go-to joint for thermo-stuff. Of course there are hundreds of other

options.



http://www.aprsworld.com/thermok/

Glenn

--

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