Today's Message Index:
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1. 01:57 AM - Are home grown temperature probes feasable? (rparigor@suffolk.lib.ny.us)
2. 06:40 AM - Re: Are home grown temperature probes feasable? (rampil)
3. 08:57 AM - Re: Are home grown temperature probes feasable? (rparigoris)
4. 09:18 AM - Re: Are home grown temperature probes feasable? (rampil)
5. 12:13 PM - Re: Are home grown temperature probes feasable? (rparigoris)
6. 01:02 PM - Re: Re: Are home grown temperature probes feasable? (rparigor@suffolk.lib.ny.us)
7. 01:06 PM - Re: Are home grown temperature probes feasible? (Robert L. Nuckolls, III)
8. 02:29 PM - Re: Are home grown temperature probes feasible? (rampil)
9. 02:35 PM - Re: Are home grown temperature probes feasable? (rampil)
10. 05:00 PM - Re: GPU for Piper (D)
11. 07:06 PM - Re: Are home grown temperature probes feasable? (J. Mcculley)
12. 07:38 PM - Re: Re: Are home grown temperature probes feasible? (rparigor@suffolk.lib.ny.us)
13. 10:05 PM - Temperature Probes (Robert L. Nuckolls, III)
14. 10:46 PM - Z-12 SD-20 wire size / fusible link size (N601RT)
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| Subject: | Are home grown temperature probes feasable? |
Not quite sure if I really want to fly my Europa or just keep finding
projects to keep on adding to build time?
AnywayI have a
Ilec SC-7 variometer. It comes with a momentary switch to view temperature
and comes with one sender. The sender is 3/16" diameter cylinder with
a flat and 3/16" long.I forget exactly what the sender is
called, but essentially it is a Zener diode. There is 3 legs of the sender
but they cut off 1 leg and only use 2 legs. The third leg they cut
offis for calibrating. You see since this was for gliders to measure
outside air temperature they have a calibration inside unit.I
figurecould calibrate several senders so they are the same then use
a rotary switch to select different locations. Senders are about a buck
each. I plan to use a rotary switch with gold contacts. OK so somehow I
figure it would be nice to have OAT, temperature under panel by radios to
see if my mini fans help, and 3 specific under cowl temperatures.
ThenI got to thinking it would be nice to monitor airbox temperature
on my 914 turbocharged Rotax with intercooler to make sure there are not
any sour spots during operation that could be conducive carb ice like high
airspeed, fine pitch and very low throttle setting, and even though I plan
to start with Evans as a coolant, might as well increase the build time
somemore and have ability to monitor coolant temperature. What I
proposeto make is an airbox probe that would begin life with a slug
of hex stock brass, then machineh NPT thread to screw in an aux hole in
existing airbox, make a .045" wall blind hole in center bout
1.5" long with a .1875" ID (3/16"). BTW close to dimensions
of UMA sender they sell except 1/2" longer. I would insert
temperature sender then fill with high temperature JB Weld.I figure
that the thin wall tube would not conduct too much heat to the airbox, yet
the tip would have sufficient contact area with sender to conduct airbox
temperature to it. Similar probe for water temperature. Thoughts on
feasability? Or not only is there something that will not work well,
butI am going to send a nice chunk of brass and semiconductor
through a hot running motor because the coolant sender breached and leaked
out all my flamable coolant directing it right onto the hot exhaust,
probably precisely towardsthe beyond red hot turbo housing of the
turbo?
All comments welcome.
Thx.
Ron Parigoris
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| Subject: | Re: Are home grown temperature probes feasable? |
Hi Ron,
Now come on, we all know you want to keep building ;-)
Dump that Evans coolant for real water!
Yes, you can make all the TC sensors you want with a small spot
welder. Performance will be highly variable until you can make the
welds perfectly uniform (for the metal-metal interface).
The best choice in your situation is to use ic temp sensors which are
factory calibrated and voltage compensated and run into a factory
built temp gauge. These sensors put out 0-5 volt so there are no issues
about microvolt voltage drops on dirty rotary switch contacts.
--------
Ira N224XS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=286640#286640
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| Subject: | Re: Are home grown temperature probes feasable? |
Hi Ira
The sender I want to use is I think the IC you describe,
not make my own thermocouple (have done that though with great success, see
below). JB Weld is a two part epoxy you can get from Aviation Isle at Home
Depot or most Hardware stores. TG from memory is like 550F and
it is probably as immune to fuel/alcohol as is Redux, just with a much
higher TG. I want to use the JB Weld Epoxy to mount my IC sender to the
tip of my turned brass blind holed hex. JB also makes a product called JB
KWIK and it is called 4 minute epoxy. TG perhaps is 350F going by memory
and strength is down perhaps 15% from JB Weld that has an 8 hour cure
time. It is probably fine for what I need in probe as far as strength and
TG, but it is far more viscous compared to JB Weld. If you warm JB Weld it
gets plenty runny to get it where I want it. JB KWIK has been invaluable
in build thus far.
BTW I have repaired many a thermocouple with using
my Hobart TRT 250 round wave TIG welder! My business is copiers and older
machines used thermocouples that were two dissimilar wires welded together
where the tip was pretty spherical. Anyway they were close to 8" long
and the tips would get brittle and a paper jam could break them. I used to
cut off an inch, jig together and go after with my TIG torch. If a nice
spherical ball happened it was then was good to go again. If the
ball was not nice just redid it till it was nice. I measured against a new
one and if ball was close to what i call nice (using my Mk 1 calibrated
"Eyechrometer") it was dead on compared to new unit. Used
same technique for other thermocouples, and where I needed longer wire
just bought same material and made a new one in desired length. >
Now come on, we all know you want to keep building ;-) The best choice in your
situation is to use ic temp sensors
which are factory calibrated and voltage compensated and run into a
factory built temp gauge. These sensors put out 0-5 volt so there are no
issues about microvolt voltage drops on dirty rotary switch
contacts.< I am pretty certain this is the sender that Ilec uses to
drive their digital readout, it is just a Zener diode. It has 3 wires and
one allows you to calibrate, or in my case match 6 of them. I imagine that
someone selling a sender could precalibrate it for their gauge, but Ilec
cuts off third leg and allows for internal calibration in their
unit. I will buy for a buck each and match calibrations for 6
senders, then calibrate Ilec to the now same values. Using a rotary switch
with gold contacts for such a flea sized amount of electrons flowing
through contacts, I am hopeful it will not cause problems of switching
thermocoulpe wires.
Ron Parigoris
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=286651#286651
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| Subject: | Re: Are home grown temperature probes feasable? |
Dont waste your time dinking with zeners!
Nice for an experiment to demonstrate principles but insane for
production use. Especially in your case where you want several, all
needing to be matched!
As I suggested for OAT, use a temp chip like for example:
http://www.analog.com/en/temperature-sensing-and-thermal-management/analog-temperature-sensors/tmp36/products/product.html
It's $0.45 in quantity! why would you even think about zeners. Jim's
spent too much time in the classroom teaching EE techs. Feasible yes,
best choice? not a chance.
PS I have 13 temp probes on my Europa
--------
Ira N224XS
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| Subject: | Re: Are home grown temperature probes feasable? |
Hi Ira
Wayne explained to me the devise I speak of operates or is based on a Zener, I
am not exactly sure which one. It is not just an ordinary Zener but a a precision
mapped thermal temperature sender and sold as such with accuracy in mapping
from one to the other of perhaps 2 or 3 degrees F, and by using the trim feature
you can adjust a lot closer than that. I apreciate your advise about not
using a Zener. The reason for selecting this specific device is that is what the
Mfg of the Ilec SC-7 vario uses to drive their thermal display.
Would you mind listing the 13 locations you have placed sensors and comment if
they would be worthy of installing if you were to do it again.
Thx.
Ron Parigoris
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http://forums.matronics.com/viewtopic.php?p=286670#286670
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| Subject: | Re: Are home grown temperature probes feasable? |
Hi Ira
The senderI want to use is I think the IC you describe,
not make my own thermocouple (have done that though with great sucess, see
below). JB Weld is a two part epoxy you can get from Aviation Isle at Home
Depot or most Hardware stores.TG from memory is like 550F and
it is probably as immune to fuel/alcohol as is Redux, just with a much
higher TG. I want to use the JB Weld Epoxy to mount my IC sender to the
tip of my turned brass blind holed hex. JB also makes a product called JB
KWIK and it is called 4 minute epoxy. TG perhaps is 350F going by memory
and strength is down perhaps 15% from JB Weld that has an 8 hour cure
time. It is probably fine for what I need in probe as far as strength and
TG, but it is far more viscous compared to JB Weld. If you warm JB Weld it
gets plenty runny to get it where I want it. JB KWIK has been invaluable
in build thus far.
BTW I have repaired many a thermocouple with using
my Hobart TRT 250 round wave TIG welder! My business is copiers and older
machines used thermocouples that were two dissimilar wires welded together
where the tip was pretty spherical. Anyway they were close to 8" long
and the tips would get brittle and a paper jam could break them. I used to
cut off an inch, jig together and go after with my TIG torch. If a nice
spherical ball happenedit was thenwas good to go again. If the
ball was not nice just redid it till it was nice. I measured against a new
one and if ball was close to what i call nice (using my Mk 1 calibrated
"Eyechrometer") it was dead on compared to new unit. Used
same technique for other thermocouples, and where I needed longer wire
just bought same material and made a new one in desired length.>
Now come on, we all know you want to keep building ;-) < You have my
number now don't you! > Dump that Evans coolant for real water!< If
my plans to keep engine kool don't quite work out, I may just do that and
install a higher pressure cap and can monitor water temp with described
probe. >The best choice in your situation is to use ic temp sensors
which are factory calibrated and voltage compensated and run into a
factory built temp gauge. These sensors put out 0-5 volt so there are no
issuesabout microvolt voltage drops on dirty rotary switch
contacts.< I am pretty certain this is the sender that Ilec uses to
drive their digital readout, it is just a Zener diode. It has 3 wires and
one allows you to calibrate, or in my case match 6 of them. I imagine that
someone selling a sender could precalibrate it for their gauge, but Ilec
cuts off third leg and allows for internal calibration in their
unit.I will buy for a buck each and match calibrations for 6
senders, then calibrate Ilec to the now same values. Using a rotary switch
with gold contacts for such a flea sizedamount of electrons flowing
through contacts, I am hopeful it will not cause problems of switching
thermocoulpe wires.
Ron Parigoris
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| Subject: | re: Are home grown temperature probes feasible? |
At 11:17 AM 2/16/2010, you wrote:
Dont waste your time dinking with zeners!
Nice for an experiment to demonstrate principles but insane for
production use. Especially in your case where you want several, all
needing to be matched!
As I suggested for OAT, use a temp chip like for example:
http://www.analog.com/en/temperature-sensing-and-thermal-management/analog-temperature-sensors/tmp36/products/product.html
It's $0.45 in quantity! why would you even think about zeners. Jim's
spent too much time in the classroom teaching EE techs. Feasible yes,
best choice? not a chance.
==================================
Good lick! You beat me to it Ira.
There is indeed a whole class of out-of-the-box, calibrated,
easy to use temperature sensors. They tend to behave like a
zener with a calibrated temperature coefficient . . . but are
indeed rather complex integrated circuits. One such device
suited to the task is:
Part Listing:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=497-7324-5-ND
Datasheet:
http://www.st.com/stonline/books/pdf/docs/2158.pdf
I've used the big brothers to this device in dozens of applications
over the years. Here's one recipe for success in wiring, packaging
and mounting this and similar devices:
http://aeroelectric.com/Pictures/Instruments/Temperature/LM135_Temp_Sensor/
I've mostly used the super-spec devices like the LM135 . . . but
for our purposes the lower cost, less accurate devices will
suffice.
The rudimentary wiring diagram illustrates the manner in which
we used these devices to feed directly into a data acquisition
system . . .
http://aeroelectric.com/Pictures/Data_Acquisition/Weeder_Module_DAS_2.jpg
monitored by an ordinary lap-top to record a multitude of
phenomenon including temperatures.
These sensors have been potted into heat sinks, 8AWG terminals
for surface mounting, drilled into the heads of bolts, glued
to surfaces (E-6000 or J-B Weld works good), etc. Many applications
simply hung the device in the open air for an ambient measurement.
If you want a direct reading, degrees C or even degrees F display,
there are low cost, LCD displays (the last picture) with a 200mV
full scale basic sensitivity. With the addition of a few 1% resistors,
perhaps a couple of pots, and a precision voltage reference, you
can re-scale and offset the reading to display degrees C directly.
But by simply scaling the device for 20 volts full scale (100:1
divider) the device will read out in degrees K. A K-degree is
the same size as a C-degree, 273K is freezing. The simpler display
isn't too hard to learn to use. Room temp is 300K, boiling is 373K.
This approach is good for about +/- 2 degrees C accuracy without
going to more sophisticated components, wiring and bench calibration.
The DAS system illustrated was supported by a PC based utility that
permitted scaling and offset adjustment to get about 0.5 degree C
accuracy.
Bob . . .
Message 8
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| Subject: | Re: Are home grown temperature probes feasible? |
Exactly Bob! I could not have said it better myself!
Lets not forget that zeners have a non-linear response to temp, whereas
the chips are exactly linear (to within reason :)) with a response of
something like 10 mV per degree from bottom to top.
Try building an analog device to replicate an arbitrary log response!
--------
Ira N224XS
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http://forums.matronics.com/viewtopic.php?p=286696#286696
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| Subject: | Re: Are home grown temperature probes feasable? |
OK Ron,
Actually, it's 15 probes (forgot Oil ;-) and internal BMA avionics temp)
4 CHT on ring probes
2 CHT on Rotax probes
4 EGT t/c
1 OAT
1 Coolant temp
1 Carb heater block
1 Oil temp
1 Blue Mountain avionics overtemp sensor (display starts at 135F)
All except two Rotax probes go to EFIS 2 system for display. All calibrated
by factory and tested by me.
OAT in lower cowl is unreliable read due to radiated engine heat
Ira
--------
Ira N224XS
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http://forums.matronics.com/viewtopic.php?p=286697#286697
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| Subject: | Re: GPU for Piper |
I've been using a pair of 7Ahr AGM batteries for ground power for my
28V system. They can be had at any of the on-line battery houses for
about $20 and are easy to maintain. Works like a charm.
Dan
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| Subject: | Re: Are home grown temperature probes feasable? |
Ron,
I'm operating a very inexpensive, minimum labor system I put together to
monitor 18 under-cowl temperatures during some 500 hours of flight
operation over the past 7 years. The cost was less than about $25 and
the accuracy is +/- 2 degrees F for temperatures less than 300F. Nothing
under the cowl aside from CHT and EGT should ever be higher than that!
Contact me directly if you want more detail.
Jim McCulley
mcculleyja@starpower.net
==============================================================================
rparigor@suffolk.lib.ny.us wrote:
> Not quite sure if I really want to fly my Europa or just keep finding
> projects to keep on adding to build time?
> Anyway I have a Ilec SC-7 variometer. It comes with a momentary switch
> to view temperature and comes with one sender. The sender is 3/16"
> diameter cylinder with a flat and 3/16" long. I forget exactly what the
> sender is called, but essentially it is a Zener diode. There is 3 legs
> of the sender but they cut off 1 leg and only use 2 legs. The third leg
> they cut off is for calibrating. You see since this was for gliders to
> measure outside air temperature they have a calibration inside unit. I
> figure could calibrate several senders so they are the same then use a
> rotary switch to select different locations. Senders are about a buck
> each. I plan to use a rotary switch with gold contacts. OK so somehow I
> figure it would be nice to have OAT, temperature under panel by radios
> to see if my mini fans help, and 3 specific under cowl temperatures.
> Then I got to thinking it would be nice to monitor airbox temperature on
> my 914 turbocharged Rotax with intercooler to make sure there are not
> any sour spots during operation that could be conducive carb ice like
> high airspeed, fine pitch and very low throttle setting, and even though
> I plan to start with Evans as a coolant, might as well increase the
> build time somemore and have ability to monitor coolant temperature.
> What I propose to make is an airbox probe that would begin life with a
> slug of hex stock brass, then machineh NPT thread to screw in an aux
> hole in existing airbox, make a .045" wall blind hole in center bout
> 1.5" long with a .1875" ID (3/16"). BTW close to dimensions of UMA
> sender they sell except 1/2" longer. I would insert temperature sender
> then fill with high temperature JB Weld. I figure that the thin wall
> tube would not conduct too much heat to the airbox, yet the tip would
> have sufficient contact area with sender to conduct airbox temperature
> to it. Similar probe for water temperature. Thoughts on feasability? Or
> not only is there something that will not work well, but I am going to
> send a nice chunk of brass and semiconductor through a hot running motor
> because the coolant sender breached and leaked out all my flamable
> coolant directing it right onto the hot exhaust, probably precisely
> towards the beyond red hot turbo housing of the turbo?
> All comments welcome.
> Thx.
> Ron Parigoris
==================================================================================
Message 12
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| Subject: | Re: re: Are home grown temperature probes feasible? |
Hi Bob and Ira
I am not at the hangar at the moment but took a look
at data sheet:
http://www.st.com/stonline/books/pdf/docs/2158.pdf
TO-92 looks like what Ilec is using, you can see the adjustment on the
datasheet I speak about, thus can match all senders so they are equal,
then i can adjust my Ilec to read correctly from any sender. We are
all on the same page. Imay have confused speaking how Ilec does
things, since they are only meant for 1 sender, they do hocus pocus
in their unit to adjust andcompensate for any tolerance error
on senders part. In my case forcing the unit that is already installed to
read correctly off of multiple senders, i will just adjust all senders to
be equal, then adjust unit.
Ron Parigoris
Message 13
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| Subject: | Temperature Probes |
At 04:14 PM 2/16/2010, you wrote:
>Hi Bob and Ira
>I am not at the hangar at the moment but took a look at data sheet:
><http://www.st.com/stonline/books/pdf/docs/2158.pdf>http://www.st.com/stonline/books/pdf/docs/2158.pdf
>TO-92 looks like what Ilec is using, you can see the adjustment on
>the datasheet I speak about, thus can match all senders so they are
>equal, then i can adjust my Ilec to read correctly from any sender.
Yeah . . . that's the LM135 series devices I was talking
about. They have an initial accuracy of 1C or about 2F.
Doing the 'adjustment' means adding components at the
temperature sensor location or bringing the third wire
back to the instrumentation package.
Consider carefully if you need better accuracy and
how hard you're willing to work to achieve it.
> We are all on the same page. I may have confused speaking how
> Ilec does things, since they are only meant for 1 sender, they do
> hocus pocus in their unit to adjust and compensate for any
> tolerance error on senders part.
Yup, that's the offset and scale factor constants that
I mentioned for the software that reads my DAS . . .
> In my case forcing the unit that is already installed to read
> correctly off of multiple senders, i will just adjust all senders
> to be equal, then adjust unit.
That will get your offset covered but see how
close they are without fiddling. If you need tighter
accuracy, then it might be worthwhile to consider
the LM135Z with an out of the box initial accuracy
of 0.5C or about 1F.
Even off the spool thermocouple wire is only +/-
2C stuff. The thermocouple signal conditioners add
another couple degrees uncertainty. I can't ever recall
a situation where we needed more temperature accuracy
than the unadjusted products offered.
Bob . . .
Message 14
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| Subject: | Z-12 SD-20 wire size / fusible link size |
Bob,
(Rev 12A) Z-12 suggests using a 10 gauge wire for the B-lead from the SD-20 with
a 16 gauge fusible link. I believe you recommend sizing fusible links with wire
that is 4 sizes smaller than the wire being protected. I'm guessing the B-lead
wire size was changed during a cut-&-paste from 12 gauge to 10 gauge without
re-sizing the fusible link? Do you recommend 10 gauge wire for an SD-20 B-lead
and if so do you recommend 14 gauge wire for a fusible link if a fusible
link is used to protect the B-lead?
Regards,
Roy
N601RT: 2003 CH601HDS, nose gear, Rotax 912ULS, All electric, IFR equipped, 1340hrs
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