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mikedjames
Samba Member
Joined: July 02, 2012
Posts: 2736
Location: Hamble, Hampshire, UK
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 Posted: Wed Jun 24, 2020 10:16 am Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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I use bead type thermocouples fitted inside isolating blobs of high temperature silicone.
The wiring is insulating sleeved all the way to the computer box. I had also trouble with ignition noise affecting the readings,. I had to use screened thermocuple leads : the thermocouple is bomded to the shield so the cable shield of the thermocouple cable is grounded via a capacitor to the case of the computer box.
I could not use any thermocouples that were electrically connected to the engine block because of the ground loop problems.
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Ancient vehicles and vessels
1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.
1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy |
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kerian159
Samba Member
Joined: February 24, 2008
Posts: 344
Location: Pensacola, FL
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| Posted: Wed Jun 24, 2020 10:22 am Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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Do you have any pics of this setup or part #'s? I'm currently attempting to learn as much as possible about this stuff while "virtually" building it on my computer.
Thanks everyone 
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1976 Type II Westy P22
"Growing older, but not up!" |
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kerian159
Samba Member
Joined: February 24, 2008
Posts: 344
Location: Pensacola, FL
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| Posted: Thu Jun 25, 2020 7:01 am Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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Here's what i'm looking at doing for my setup. Using insulated Thermocouples and all the rest of the do-dads
Let me know what you think, parts used are listed above the project
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1976 Type II Westy P22
"Growing older, but not up!" |
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telford dorr
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Joined: March 11, 2009
Posts: 3551
Location: San Diego (Encinitas)
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| Posted: Thu Jun 25, 2020 11:40 am Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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Looks like it ought to work (with the isolated thermocouples). Let us know how testing goes...
You could get fancy and add four more as EGT probes...
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'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST) |
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ivwshane
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Joined: May 19, 2011
Posts: 1920
Location: Sacramento ca
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| Posted: Thu Jun 25, 2020 12:10 pm Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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| kerian159 wrote: |
Here's what i'm looking at doing for my setup. Using insulated Thermocouples and all the rest of the do-dads
Let me know what you think, parts used are listed above the project |
I can’t offer any advice but I wanted to thank you for posting your setup in an easy to understand picture.
How does the software side work though? Is it like the raspberry pi where you have an underlying OS and then a software package you run or is it more/less involved?
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77 westy 2.0 FI
69 ghia coup 1600dp
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telford dorr
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Joined: March 11, 2009
Posts: 3551
Location: San Diego (Encinitas)
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| Posted: Thu Jun 25, 2020 12:25 pm Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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No OS per se - just board specific initialization code. Then the following is called:
| Code: |
setup(); // Your initialization code
while( 1 )
loop(); // Your program code |
You write the setup() and loop() subroutines (GCC compiler: C or C++ - your choice). Loop never exits.
You can add and link in any other code modules, library modules or object classes you want (until you run out of memory..)
It's a great development platform for quick-and-dirty projects or, as I do, for programming an atmega328p processor chip which I then hardwire into a final project.
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST) |
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ivwshane
Samba Member
Joined: May 19, 2011
Posts: 1920
Location: Sacramento ca
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| Posted: Thu Jun 25, 2020 12:53 pm Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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Are there already pre-written modules for displaying the output? I’d imagine the code for the sensors would be something, get value from pin # every X time and then you pass that value to the display module. As you may or may not know, I don’t know how to program so this would be the biggest hurdle for me (the wiring/soldering I can do).
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77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab |
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telford dorr
Samba Member
Joined: March 11, 2009
Posts: 3551
Location: San Diego (Encinitas)
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| Posted: Thu Jun 25, 2020 12:55 pm Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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There's an endless supply of libraries to support just about any display you want (often provided by the display vendor), so that shouldn't be an issue. And the development environment (IDE) supports a serial link to the board that you can get data from it and use your laptop as the display (as done above).
You will need some programming experience, but this is a good platform to learn on, as they provide quite a library of example code (from simply blinking a LED up to controlling servo motors) to explore.
Check out Arduino.cc
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'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST) |
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kerian159
Samba Member
Joined: February 24, 2008
Posts: 344
Location: Pensacola, FL
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| Posted: Fri Jun 26, 2020 5:40 am Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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As soon as I get the code done i'll post it on here as well but that's going to take some time as I am definitely not a programmer (Hardware is much easier for me) but I do know some people both here and externally that are! So hopefully it won't take too long.
As soon as I find an Isolated Thermocouple i'll post that here as well
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1976 Type II Westy P22
"Growing older, but not up!" |
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a-marshal
Samba Member
Joined: March 21, 2009
Posts: 270
Location: Toronto
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| Posted: Fri Jun 26, 2020 5:55 am Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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| kerian159 wrote: |
Here's what i'm looking at doing for my setup. Using insulated Thermocouples and all the rest of the do-dads
Let me know what you think, parts used are listed above the project |
I used analog thermocouple amps from Adafruit, so I can't give any advice on the digital ones in your drawing, however I would recommend you test your screen in daylight driving conditions. I tried LCD and TFT screens and I found I wasn't able to read them on a sunny day. I ended up using a monochrome OLED from Adafruit like this one (but the now discontinued 1.3" much cheaper version)
https://www.adafruit.com/product/2720 OLED
You show a 9 Volt battery feeding a step down converter, if you were to throw a switch or a relay before the buck converter you could use battery power..
FWIW, I ended up using home made thermocouples, I tried a number of different commercial ones including Dakota Digital and found them lacking in one way or another*. None of the ones I purchased, including the DD, were isolated so I have simply assumed that the insulation is at the amplifier end. (In any event it worked in testing and has worked for a couple years in actual use so I must have done something right..)
* some were too bulky to fit the sparkplug recess while others were too flimsy not to distort when torquing the plugs.
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kerian159
Samba Member
Joined: February 24, 2008
Posts: 344
Location: Pensacola, FL
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| Posted: Fri Jun 26, 2020 6:05 am Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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The software I used to draw the diagram did not have any 12V symbols, I used a 9V battery and noted it next to it before going into a buck . The screen is at the moment just a placeholder for something else, an OLED would be great and you do have a point about the sun.
As for your homemade thermocouples could you give some more details on that, as that's one of my biggest variables still. 
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"Growing older, but not up!" |
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kerian159
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Joined: February 24, 2008
Posts: 344
Location: Pensacola, FL
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a-marshal
Samba Member
Joined: March 21, 2009
Posts: 270
Location: Toronto
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| Posted: Fri Jun 26, 2020 9:11 am Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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| kerian159 wrote: |
| The software I used to draw the diagram did not have any 12V symbols, I used a 9V battery and noted it next to it before going into a buck . |
I saw the big picture and didn't read the fine print... sadly that is a bit of a habit with me
| kerian159 wrote: |
| As for your homemade thermocouples could you give some more details on that, as that's one of my biggest variables still. |
I bought steel wrapped Type-K wire and Type-K connectors off ebay
much like these.
https://www.ebay.ca/itm/K-Type-Stainless-Steel-Shi...SwI~FdSp0e
and
https://www.ebay.ca/itm/Mini-K-Type-Thermocouple-W...Sw64NcmW~M
I then cut out my own ring terminals from 24 gauge copper sheet.
I used a step drill to cut a 9/16 hole (14.28mm) for the plug. (at least two of the purchased terminals that claimed to be 14mm were really 9/16).
After drilling there was room for over 1/8 inch of material to clear the spark plug body which I cut with tin snips, leaving a small tab to crimp the
wires to. I left the tabs just over 1/4 inch long so they wouldn't interfere with the wrench and I tried to keep them as close to the same length as possible.
I cleaned everything up with a file and a dremel I then pre-bent the tabs so I was sure they would clear the plug body and not bind or bend.
For the thermocouple wire itself I simply made a physical connection, twisting the last couple mm of the wires together, making sure that they are as close to the same as possible. I wrapped all of it but the actual connection with high temp shrink wrap. I crimped the clean end into the tab I made and added some solder to help prevent it working loose.
I used copper spark plug gaskets rather than the plugs crush washers and put my ring between the gasket and the plug. (I can get plug gaskets cheaply and easily while replacement crush washers are harder to come by at a decent price.)
Reading this again it sounds pretty mickey mouse but the results were better than some of the things I was sold...
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kerian159
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Joined: February 24, 2008
Posts: 344
Location: Pensacola, FL
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| Posted: Fri Jun 26, 2020 9:26 am Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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Cool, thanks as i'm going to be using some digital parts in this I think i could just connect the one end to a washer (like you've done) and then the other side to my setup and it'd work without that connector. Anybody see any issues with this setup?
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"Growing older, but not up!" |
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a-marshal
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Joined: March 21, 2009
Posts: 270
Location: Toronto
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| Posted: Fri Jun 26, 2020 9:28 am Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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Not sure, it looks like the thermocouple terminates in the end of that rigid wire, rather than attaching directly to the sensor ring.
That isn't a problem in and of itself but if it is that way then the wire would be in the cooling airflow and I don't know what affect that would have on the readings..
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1973 Westy w/ '74 1.8 liter / PDSI (type3?) carbs / 009 distributor / pertronix |
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a-marshal
Samba Member
Joined: March 21, 2009
Posts: 270
Location: Toronto
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| Posted: Fri Jun 26, 2020 9:36 am Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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| kerian159 wrote: |
| Cool, thanks as i'm going to be using some digital parts in this I think i could just connect the one end to a washer (like you've done) and then the other side to my setup and it'd work without that connector. Anybody see any issues with this setup? |
I found I needed the tab, I tried at one point to connect directly to the copper gasket but it didn't work out, the plug either wouldn't seat correctly or I ripped the wire off when torquing it down.
A number of people have had good luck potting the thermocouple directly into the head, I would have done that if my engine were out. (the next time it comes out I will likely make that change)
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kerian159
Samba Member
Joined: February 24, 2008
Posts: 344
Location: Pensacola, FL
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| Posted: Fri Jun 26, 2020 10:17 am Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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Ok cleaned up the image a bit and updated some components that i've found that will make this project a bit easier (i think). I've also removed the screen as i'm not entirely sure what i'm going to be using at this moment and i'm going to get focused on making the system actually work (display to a computer via USB for the moment).
On the programming side of things i've found a link that is very promising i'll link it below. Scroll down until you get to the Arduino programing area (about 1/4 the way down)
https://learn.adafruit.com/adafruit-1-wire-thermocouple-amplifier-max31850k/wiring-and-test
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mikedjames
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Joined: July 02, 2012
Posts: 2736
Location: Hamble, Hampshire, UK
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| Posted: Fri Jun 26, 2020 10:43 am Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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The great thing with thermocouples with modern amplifiers is that its the junction voltage where the wires aee bonded you are measuring. What happens to the wire en route is irrelevant because little current is flowing.
The other end at the amplifier you need to make sure the +,and - connections are at the same temperature as each other.
Old school with microamp meter the resistance of the leads made a difference. So cooking the wire changed the reading.
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Ancient vehicles and vessels
1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.
1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy |
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kerian159
Samba Member
Joined: February 24, 2008
Posts: 344
Location: Pensacola, FL
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| Posted: Fri Jun 26, 2020 10:45 am Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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Very true, but from what i've been reading it will just throw the temp reading negative so it wouldn't be too difficult to resolve
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"Growing older, but not up!" |
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kerian159
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Joined: February 24, 2008
Posts: 344
Location: Pensacola, FL
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| Posted: Mon Jun 29, 2020 10:41 am Post subject: Re: Arduino CHT, Oil temp, Oil Pressure |
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Ok i've ordered most of the parts to start mocking this contraption up (i'll post progress as it happens) but i've finished up the drawing with an LCD that is RGB so it is backlit for when the sun is out I can change the colors fairly easy (still need to wire that part up though) but here she is for the time being. Oh and this is MK-VII if anybody is/cares to keep track (other than me).
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