Poor mans dakota digital

[RocketSurgeon]

Less than $30 shipped from Hong Kong. Cold junction compensation, 18' k type wire, ss sheathing, blue digital display that refreshes every 1/2 second. The electronics look top notch but the plastic housing is second rate. I'll consider it an experiment if it breaks in a week. At least the thermocouple looks like it will last.
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69 Westy

[aerosurfer]

Im game.... gotta link?
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Rebuild your own FI Harness..My Harness

77 Westy 2.0L Rockin and Rolling Resto!

72 Sportsmobile (sold)
79 Tran$porter... Parts car money machine (gone)

[RocketSurgeon]

eBay, just search "dc thermocouple meter". The same guy can sell custom length thermocouples.

I took a look inside and I am almost positive this thing doesn't have cold junction compensation, even if the literature says it does.

(Ambient temp -72)+meter = actual CHT
I'll keep a thermometer on the dash for reference.

Here it is mocked up.

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69 Westy

[jtauxe]

Well, it fits nicely in that block-off plate, which is where I would consider putting gauges anyway. But the display is bigger than it has to be. I expect an electronics whiz could redo a readout that would be much smaller, which would allow more room for other gauges there.

I look forward to hearing about what you think of the thing once you have tried it out for real.
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John
"Travelling in a fried-out Kombi, on a hippie trail, head full of zombie..." - Colin Hay and Ron Strykert
http://vw.tauxe.net
1969 Transporter, 1971 Westfalia, 1976, 1977, 1976, 1977, 1971, 1973, 1977 Westfalias,
1979 Champagne Sunroof, 1974 Westfalia Automatic, 1979 Transporter, 1972 Sportsmobile, 1973 Transporter Wild Westerner, 1974 Westfalia parts bus, 1975 Mexican single cab *FOR SALE*, 1978 Irish 4-door double cab RHD

[RocketSurgeon]

I think the size is just right. The numbers are like an inch tall. Big enough where I won't be looking at it all the time but if I see a 400 I'll know right away.
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69 Westy

[mojogoat]

I see some with 4 readouts, interesting, looks like I'll have to buy a couple, great find and thanks for sharing.
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77 Riviera
78 CEII Westfalia

[WendyArmbuster]

I'm glad you mentioned this. I am planning a poor man's cht gauge too. I am going to buy some thermocouple wire and a MAX6675 temperature compensated amplifier chip for it, which will output to a Picaxe chip, which will send a signal to a servo that I am going to mount in my clock block plate for analog CHT. There's a few other parts I'll need, like a 5v regulator for high noise applications and some capacitors and resistors, but I'm hoping to build it for less than $50. A lot of time, but I enjoy electronics projects.

Chips that amplify thermocouple voltages often have temperature compensation, and are pretty cheap when bought in bulk. I wouldn't doubt if yours has temperature compensation. It's sort of amazing that the vdo gauge doesn't.
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Brian Z
1978 Westfalia

[RocketSurgeon]

Brian, my original idea was to put in an audrino board with multiple sensors for cylinder head temp, oil temp and oil pressure all displayed on a nice digital face that would fill the radio hole. Throw in a time display and a buzzer for programmed high temps and I'll be set. Maybe one day.
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69 Westy

[sambabus]

I'd like to use an old android or iphone as a color touchscreen display and use one of the many apps that work with OBD2 cars. Maybe adapt a computer from the junkyard and just use the sensor part. There must be someone in this group that can hack this.
I also have my gauges mounted in the radio blank...
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1971 Westy, 2017cc 78.4 x 90.5 Tims Stage 1 plus 42x37, CB 44IDF's, 135 mains, 175 airs, F111, 50 idles, Engle 110, 30mm, 009, single QP, DD CHT 300*f, VDO oil always 180* Build: http://www.thesamba.com/vw/forum/viewtopic.php?t=541370
1970 convertible bug, 1835cc, single 40IDF, disks.
Symptoms Solved and Fixed http://www.thesamba.com/vw/forum/viewtopic.php?t=551358

[bigdan.theplumber]

So, I hardly ever post anything on here. I mostly just lurk but, this is a subject I've given quite a bit of thought to.

I've been wanting to make an Open source OBD2 compliant ECU based off of an arduino. By making it OBD2 compliant you could output sensor data in a format that is readable by many scan tools. Specifically, I would like to use one of the bluetooth ones based off the elm327 chip so I can use the "Torque" app on my android tablet which I intend to mount in a custom headliner console above the dash board. I also intend to have a bunch of RGB LED's controled by the android tablet and an arduino so, I can make my bus look like a UFO (LOL).

Reading sensor information is fairly easy with the analog inputs. So, things like oil pressure, oil temperature, should be easy, Reading micro voltages seems a little tricky so things like CHT or a wide band O2 Sensor seem a little difficult but it would be pretty sweet.

I'm interested in trying to use the chinese CHT module with an arduino. I may have to buy one of these soon to try it out. MORE RESEARCH!

I work with arduinos on a regular basis so I feel comfortable with doing it. It's mostly just a matter of devoting my time. I barely have enough time to work on my bus as it is.

[sambabus]

I just ordered a wifi elm327 to work with my iphone, the bluetooth one doesn't. How much does a arduino cost? If you did it that way it would be a standard platform.
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1971 Westy, 2017cc 78.4 x 90.5 Tims Stage 1 plus 42x37, CB 44IDF's, 135 mains, 175 airs, F111, 50 idles, Engle 110, 30mm, 009, single QP, DD CHT 300*f, VDO oil always 180* Build: http://www.thesamba.com/vw/forum/viewtopic.php?t=541370
1970 convertible bug, 1835cc, single 40IDF, disks.
Symptoms Solved and Fixed http://www.thesamba.com/vw/forum/viewtopic.php?t=551358

[udidwht]

Or this:

http://www.ot-2.com/
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1972 Westy Hardtop/Type-4 2056cc
96mm Biral AA P/C's~7.8:1CR
Headflow Masters New AMC 42x36mm heads w/Porsche swivel adjusters
71mm Stroke
73 Web Cam w/Web solids
Dual 40mm IDF Webers - LM-2 - 47.5 idles/125 mains/190 air corr./F11 tubes/28mm Vents - Float height 10.45mm/Drop 32mm
Bosch SVDA w/Pertronix module (7.5 initial 28 total @ 3400rpm)
Bosch W8CC plugs
Pertronix Flamethrower 40K coil
S&S 4-1 w/Walker QP 17862
3 rib 002 Trans
185R14 Hankook tires

[Brian]

[Brian]

[aerosurfer]

So Im Very New learning my equipment for this project,

In the first picture you have a thermocoupler cable that has 2 loose ends, but all the ebay sellers show it having the yellow type connector. did you just cut the end and put your own leads on?

Also How do you drop the motor with the leads attached? Or if you damage the Coupler at the head, is there a way to have a short 3'-6' lead with a connector to the line that goes forward? For easy replacement?

Edited for above..... So I see connectors are available, is there any parasite loss other considerations when using the connectors vs a single wire to the unit?

Also, none of the auctions mention about cold junction compensation, was there a particular one you got or just noticed when you got it?
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Rebuild your own FI Harness..My Harness

77 Westy 2.0L Rockin and Rolling Resto!

72 Sportsmobile (sold)
79 Tran$porter... Parts car money machine (gone)

[RocketSurgeon]

Thermocouples are simple. Two wires of different metal welded at one end will make a voltage at the other. The cold junction is just the end of the wires where you connect to the meter(since this wire has no breaks or extensions).

There are connectors made that match the two same metals in the wires. This way you can have a disconnect in the engine bay and have no effect on the reading. Each wire/tab/screw only touches matching metal so no voltage is created.

My wire came with the tabs on it. I just cut them off and striped the wire back to go on the meter. "Cold junction compensation" is written in the instructions but the whole thing is such a bad misspelled translation I don't know what is trying to be said. I did let it sit in the bus a few hours yesterday and it did read close to the correct temp from a thermometer I had a few inches away. Maybe there is an actual cold compensation circuit I there somehow.
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69 Westy

[Tcash]

Hi RocketSurgeon
Trying to sort this out and had a few questions?

Is this the unit you are talking about?
Digital DC Temperature Meter for K Type EGT Probe with Blue LED (12V / F)

You have to order an 18 foot version of this from the vendor?
Thermocouple K type with 14mm id Washer for Cylinder Head Temperature (CHT)

You can use a CHT or this EGT Sensor with it?
EGT K Type Thermocouple Temperature Sensors for Exhaust Gas Temperture Probe

If you wanted to add a connector at the firewall, so you could unplug it to drop the motor? Could you use one of these?
http://www.omega.com/pptst/SMPW-CC.html

Are all the notations in red correct?

Thank You
Tcash

[RocketSurgeon]

Spot on!

There is also a red faced meter and a "4 readout" meter that will work. I don't want this to turn into an ad for the guy but that's what I bought.

I don't know if the EGT probe will work anywhere on a head, but should read just fine as long as you stay with a K type.

Also make sure you get a "Fahrenheit" meter.
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69 Westy

[Tcash]

Thank you.
I was thinking you could buy another meter and EGT sensor, weld a 1/8 NPT bung into the exhaust collector and collect that data.

[RocketSurgeon]

Not a bad idea. The radio delete plate is almost made to hold two meters. I'm thinking if this one works out I might want another for oil temp.

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69 Westy