New beta version of openXsensor (=openXvario)

Development & General Chat for the superb openxvario project.

Moderator: rainer

User avatar
jhsa
Posts: 16676
Joined: Tue Dec 27, 2011 5:13 pm
Country: Germany

Re: New beta version of openXsensor (=openXvario)

Post by jhsa » Mon May 01, 2017 4:16 pm

well, it does change the resistance according to the temperature. It is however very low..

Will try later to place both sensors on the aluminum plate and heat them up with the heat gun.. I would expect no differences at 150º then, and not so much difference also in between. 2 or 3 degrees are more than acceptable..

What do you intend to do for other NTC sensors that might not match these specs?
How easy will be to calculate the 3 calibration points using the datasheet?
I expect some complicated formula?? ;) :)

Thanks

João
My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

Donate to Er9x/Ersky9x:
https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=YHX43JR3J7XGW

mstrens
Posts: 1066
Joined: Fri Dec 27, 2013 7:49 pm
Country: -

Re: New beta version of openXsensor (=openXvario)

Post by mstrens » Mon May 01, 2017 5:05 pm

the formula to calculate A B C based on the 3 sets of resistance/temperature is given in wikipedia
see here (under the title Steinhart–Hart coefficients)
https://en.wikipedia.org/wiki/Steinhart ... efficients

It is not so difficult to implement in xls

User avatar
jhsa
Posts: 16676
Joined: Tue Dec 27, 2011 5:13 pm
Country: Germany

Re: New beta version of openXsensor (=openXvario)

Post by jhsa » Tue May 02, 2017 11:48 am

Tried with the hot air gun, but the sensors give complete different temperatures, with the multimeter now going much higher than the other sensor being tested. Like 50 or 60 degrees difference :( Like this is impossible:(
need to find a better way.. and will have to repeat the water test :o

João
My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

Donate to Er9x/Ersky9x:
https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=YHX43JR3J7XGW

mstrens
Posts: 1066
Joined: Fri Dec 27, 2013 7:49 pm
Country: -

Re: New beta version of openXsensor (=openXvario)

Post by mstrens » Tue May 02, 2017 12:30 pm

Perhaps you are becoming out of range for your multitester temp sensor?

If you have an electric oven with a thermostat,I think it could be used. Accuracy of thermostat is probably be about 10 °c .
So it will already be better than 50/60 degree.

Alternative is an electric fryer. It has a thermostat that goes normally up to 180 °C.

User avatar
jhsa
Posts: 16676
Joined: Tue Dec 27, 2011 5:13 pm
Country: Germany

Re: New beta version of openXsensor (=openXvario)

Post by jhsa » Tue May 02, 2017 1:28 pm

Yes, but my oven is not digital, so i can't see the temperature. And I don't see how I can put the wires outside. The plugs on the sensors will melt.. They are plastic..

I also do not own an electric fryer..
the problem is that with the heat gun, even under 100 degrees there was a big difference.
yesterday, with both sensors inside a bit of plastic bag, and inside the water, they were reporting similar temperatures. So the best would be to read the temperature of a liquid??
Maybe cooking oil?? have a look:

The smoke point for some common cooking oils are here:

Safflower - 510 F (266 C)
Soybean - 495 F (257 C)
Corn - 475 F (246 C)
Peanut - 440 F (227 C)
Sesame - 420 F (216 C)
Olive - 375 F (191 C)

They are a bit higher than 150 degrees, but just to compare maybe i could try it??

João
My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

Donate to Er9x/Ersky9x:
https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=YHX43JR3J7XGW


User avatar
Kilrah
Posts: 9099
Joined: Sat Feb 18, 2012 6:56 pm
Country: Switzerland

Re: New beta version of openXsensor (=openXvario)

Post by Kilrah » Wed May 03, 2017 8:29 am

temp-regulated soldering iron?

User avatar
jhsa
Posts: 16676
Joined: Tue Dec 27, 2011 5:13 pm
Country: Germany

Re: New beta version of openXsensor (=openXvario)

Post by jhsa » Wed May 03, 2017 9:00 am

Can try that, but most calibrating docs I find speak about baths, and that makes sense to me as both sensors would be at the same temp, and the temp around the sensor would be uniform..

João

Sent from my thor using Tapatalk

My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

Donate to Er9x/Ersky9x:
https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=YHX43JR3J7XGW

User avatar
jhsa
Posts: 16676
Joined: Tue Dec 27, 2011 5:13 pm
Country: Germany

Re: New beta version of openXsensor (=openXvario)

Post by jhsa » Wed May 03, 2017 9:02 am

I will probably try sunflower oil, which has a smoke point of around 227 degrees C. I believe it is not conductive so I wouldn't probably need a plastic bag to protect it.. I think it would melt anyway :)

João

Sent from my thor using Tapatalk

My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

Donate to Er9x/Ersky9x:
https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=YHX43JR3J7XGW

User avatar
jhsa
Posts: 16676
Joined: Tue Dec 27, 2011 5:13 pm
Country: Germany

Re: New beta version of openXsensor (=openXvario)

Post by jhsa » Wed May 03, 2017 10:53 am

Just tried the soldering iron set to 150º.
The multimeter reads between 155 and 160º

My radio not even 100º. The water test was ok, so I guess I will have to make the oil test.

João
My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

Donate to Er9x/Ersky9x:
https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=YHX43JR3J7XGW

User avatar
jhsa
Posts: 16676
Joined: Tue Dec 27, 2011 5:13 pm
Country: Germany

Re: New beta version of openXsensor (=openXvario)

Post by jhsa » Wed May 03, 2017 2:25 pm

Ok, I think the oil test, after a water test to calibrate the 100º C is the way to go.
No plastic around the sensors this time. Just immerse them in the "vegetable cooking" oil..
Here is the first measurements I took, but I did something a bit wrong. I set the cooker at full power, and I think one sensor responds faster than the other at temperature changes.


Multi --- Radio
40 ------------ 39
50 ------------ 48
57 ------------ 55
66 ------------ 63
75 ------------ 73
92 ------------ 90
113 -----------109
126 -----------120
140 -----------134
150 -----------143
158 -----------150
170 -----------164

As you can see as the temperature was going up quite fast, there was a bit of difference starting at about 120º until the 170º mark.
But then while cooling down, both seem to match better. Also removing the sensors from the oil and putting them there again showed similar temperatures on both sensors, as you can see on this video

https://www.youtube.com/watch?v=p-PImqCqkmg

While the oil was cooling down, I took some resistance measurements. Comparing them to the sensor datasheet I posted somewhere above, it seems that the resistance values match the table. Here are my measurements:

Temp in degrees ºC and resistance in Ohms

190º --- 730
179º --- 883
165º --- 1270
150º --- 1675 - Expected 1770
130º --- 2780 - Expected 2940
120º --- 3667 - Expected 3850
110º --- 5040 - Expected 5070
102º --- 6170
98º --- 7100
90º --- 9160 - Expected 9100

As you can see, the values are quite close to the datasheet values. They are approximate because the numbers were always changing, making it difficult to take an exact measaurement..
Now i just have to flash the other oxs that is connected to the sensor on the engine and run it.
Thanks to this testing I found out that I was probably overheating the engine due to a wrong propeller size.
Comparing the results from this test and the soldering iron test, I have learnt that the sensor has to be very well attached to the cylinder head, making good contact with it..

João
My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

Donate to Er9x/Ersky9x:
https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=YHX43JR3J7XGW

mstrens
Posts: 1066
Joined: Fri Dec 27, 2013 7:49 pm
Country: -

Re: New beta version of openXsensor (=openXvario)

Post by mstrens » Wed May 03, 2017 5:10 pm

Probably you can glue it with silicone

User avatar
jhsa
Posts: 16676
Joined: Tue Dec 27, 2011 5:13 pm
Country: Germany

Re: New beta version of openXsensor (=openXvario)

Post by jhsa » Wed May 03, 2017 6:03 pm

On the test engine I did glue with 5 minute epoxy between the cooling fins, right near the glow plug.
But the epoxy gets a bit soft with higher temperature.. I don't know if silicone is a good idea because of vibrations and temperature..
I might try 24 hour epoxy on the model's engine. the critical part is the sensor placement.it must be in contact with the base of the cylinder head..
waiting for better weather to test it with the engine running..

João
My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

Donate to Er9x/Ersky9x:
https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=YHX43JR3J7XGW

mstrens
Posts: 1066
Joined: Fri Dec 27, 2013 7:49 pm
Country: -

Re: New beta version of openXsensor (=openXvario)

Post by mstrens » Wed May 03, 2017 8:22 pm

I think that silicone support higher temp than epoxy.

User avatar
Kilrah
Posts: 9099
Joined: Sat Feb 18, 2012 6:56 pm
Country: Switzerland

Re: New beta version of openXsensor (=openXvario)

Post by Kilrah » Wed May 03, 2017 9:44 pm

Yup by far. Epoxy doesn't hold more than 150°C or so, silicone is usually still happy at double that.

User avatar
jhsa
Posts: 16676
Joined: Tue Dec 27, 2011 5:13 pm
Country: Germany

Re: New beta version of openXsensor (=openXvario)

Post by jhsa » Wed May 03, 2017 9:51 pm

But are you talking normal silicone that you use for example to seal the bath in the bathroom, or the high temperature silicone.. This is subject that I don't know much about..
I believe that silicone is also soft, rubber type, after drying? what about heat transfer properties? Sorry about my ignorance guys..

João
My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

Donate to Er9x/Ersky9x:
https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=YHX43JR3J7XGW

mstrens
Posts: 1066
Joined: Fri Dec 27, 2013 7:49 pm
Country: -

Re: New beta version of openXsensor (=openXvario)

Post by mstrens » Thu May 04, 2017 7:07 am

I have no experience but I read that silicone can support temperature up to 300 °C.
Still I am not sure that the most common one (for e.g. bathroom) can support 300°C.
I see that there are plenty of offers when I search for silicone high temperature.
I expect you can even find them in normal hobby shops.

User avatar
jhsa
Posts: 16676
Joined: Tue Dec 27, 2011 5:13 pm
Country: Germany

Re: New beta version of openXsensor (=openXvario)

Post by jhsa » Thu May 04, 2017 7:59 am

Thanks, I will make some experiments. I think I might still have some laying around. Will simulate gluing a sensor to an engine using it and apply some heat gun power to it. ;) :)

João

Sent from my thor using Tapatalk

My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

Donate to Er9x/Ersky9x:
https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=YHX43JR3J7XGW

frater
Posts: 76
Joined: Sat Aug 30, 2014 11:04 pm
Country: -

Re: New beta version of openXsensor (=openXvario)

Post by frater » Tue May 09, 2017 5:04 am

There are special glues that withstand higher temperatures and I used one in the past to glue the engine of my motorbike. It had a hole after I fell with it. The trick with these glues is that they not only withstand higher temperatures but they also expand and contract the same as the materials for which they are designed.

I used a 120° version, which should be enough for the engine itself. There are higher temperature versions of that glue which can withstand the heat at the exhaust. I believe that's 300°.

These glues are especially designed for this purpose.


User avatar
bob195558
Posts: 1560
Joined: Sun Dec 16, 2012 7:24 pm
Country: United States
Location: New England, Vermont
Contact:

Re: New beta version of openXsensor (=openXvario)

Post by bob195558 » Tue May 09, 2017 10:19 am

There is a Red higher temperature silicone too, (https://www.delcity.net/store/Red-Silic ... gJJmPD_BwE).
Effective temperature range: -80°F to 650°F (-62° to 343°C), intermittent 650°F exposure only.

Bob B.
RADIOS: ErSky9x on Taranis, ErSky9x on Sky9x, ErSky9x on 9Xtreme,
Er9x-FrSky on 9x-Radio with Smartieparts upgrade Programmer Board and 9x-TelemetrEZ Board.
Some help info here: (http://openrcforums.com/forum/viewtopic.php?f=95&t=7182).
Bob B.

User avatar
jhsa
Posts: 16676
Joined: Tue Dec 27, 2011 5:13 pm
Country: Germany

Re: New beta version of openXsensor (=openXvario)

Post by jhsa » Tue May 09, 2017 10:24 am

Yes, I have that, but it might not be good to glue the sensor to the engine.. It is just like rubber..
I think I will try 24 hour epoxy..

João

Sent from my thor using Tapatalk

My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

Donate to Er9x/Ersky9x:
https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=YHX43JR3J7XGW

hillflyer
Posts: 4
Joined: Sat Jul 02, 2016 7:36 pm
Country: Germany

Re: New beta version of openXsensor (=openXvario)

Post by hillflyer » Thu May 11, 2017 9:24 pm

Hello,
try thermal compound glue.
Availabale on ebay starting at a dollar or so.
It looks like heatsink grease, but hardens in a few hours.
Cheers,
H.

Beloh
Posts: 2
Joined: Sun May 28, 2017 11:11 am
Country: -

Re: New beta version of openXsensor (=openXvario)

Post by Beloh » Sun May 28, 2017 11:30 am

Hallo,
Sorry for my bad english.
I bild a openxsensor with ADS1115 and monitored single cells 4S Lipo.
But i transmit to Taranis only accx, accy accz and fuel for ads-volt1-4.
How can I get cells and than in Taranis cellmin?
I think an extension in config to switch between volt1-4 and ads-volt1-4 could solve the problem
Beloh

mstrens
Posts: 1066
Joined: Fri Dec 27, 2013 7:49 pm
Country: -

Re: New beta version of openXsensor (=openXvario)

Post by mstrens » Sun May 28, 2017 7:19 pm

When an ADS1115 is used, current version of oXs let send to Tx the (up to) 4 voltages being measured.
It does not calculate each cell voltage nor the minimum.

I expect that with openTx you can perform the calculations you ask for based on the 4 voltages.
Perhaps you can do it using calculated fields in the telemetry panel.
Otherwise you can for sure do it with a LUA script.

Performing the calculations in oXs would be possible but it would require adding some code.
Such a code already exist when you measure the cells with the analog pins of Arduino. The accuracy is not so good as with an ads1115 but I expect it is good enough for normal use (probably that the error is less than 10 mvolt if scale and offset are used).
So I ask myself if it is really needed to add code for ads1115 option.

Beloh
Posts: 2
Joined: Sun May 28, 2017 11:11 am
Country: -

Re: New beta version of openXsensor (=openXvario)

Post by Beloh » Sun May 28, 2017 9:14 pm

Thank you very much for the answer. I will try a LUA-Script
Beloh

User avatar
kalle123
Posts: 685
Joined: Sat Mar 29, 2014 10:59 am
Country: -
Location: Moenchengladbach

Re: New beta version of openXsensor (=openXvario)

Post by kalle123 » Mon May 29, 2017 5:01 pm

I still use master oXs 8.0 and the analog pins of Arduino for voltage measurement.
OK, calibration is a little work to get accuracy. But after that accuracy is quite acceptable ....

Zebble
Posts: 7
Joined: Tue Apr 11, 2017 4:38 pm
Country: -

Re: New beta version of openXsensor (=openXvario)

Post by Zebble » Wed Jun 28, 2017 11:43 pm

Zebble wrote:
Tue Apr 18, 2017 12:46 am
mstrens wrote:
Mon Apr 17, 2017 6:47 am
I have prepared a new version where you can measure up to 6 NTC (with the same characteristics).
When there is only one or two, you can get the temperature(s).
When there are more than 2, you get the lowest and highest temperature and the index of the highest.

I will put it soon on github
That's great mstrens! Thanks so much. Looking forward to testing.
*Finally* had a chance to test...

NTC code is working really well! Only 2 sensors right now, but very responsive and appears to be accurate enough for our needs (cylinder head).

Post Reply

Return to “OpenXVario - an open source vario supported by the open source firmwares!!”

Who is online

Users browsing this forum: No registered users and 1 guest