Adding coolant temp gauge? (1 Viewer)

[RavenTai]

the first is from the left side in the first pic kind of lookign along its length


And the last two are from the back side between the air core motor of the water temp gauge and the oil pressure gauge movement.

So Rich what are you thinking about? Any ideas? I will have its values after testing but would still be nice to get as much info as possible before hand.

 

[RavenTai]

R2 I am glad you like the book, it ws a verry good value at $7 but free is even better. there is a nice group here

 

[Rookie2]

still have not been able to find out what the boiling temperature of water is at my altitude but it is only ~840’ above seal level at the house so not much less than 212* F, I would think within 2-3 * F should be accurate enough for this purpose. 212 is a nice calibration point as the temperatures we are primarily interested in are in this area and is easy to accurately achieve.

Here's a link for a boiling point calculator:

http://www.biggreenegg.com/boilingPoint.htm

You've also got to input the current barometric pressure, as that has an impact also. If you've got the number for ASOS (Automated Surface Observation Service) at your closest airport, you should be able to call up and get the real time barometric pressure. If you can't get ahold of the ASOS number at you're closest Airport, let me know which one your closest to you and I'll see if I can look it up. Either that, or weather.com may do.


Rookie2

 

[Rich]

...
So Rich what are you thinking about? Any ideas?...

I was just hoping to get enough info to identify the diode in order to ascertain its specifications. Any markings of the meter itself?

 

[RavenTai]

Thanks R2 that is a great link, standard day (29.92 hg") 840' gets 210.5* F,

Found this stream witch would be my closest airport, seams about 5 hours behind

http://weather.noaa.gov/weather/current/KCCO.html

And this one witch is only 2 hours behind (bigger airport and regional home of the FAA)

http://weather.noaa.gov/weather/current/KFFC.html

I’ll try to find that number for either of those fields

 

[RavenTai]

Rich I'll give the makings when I get home from work.

 

[Rookie2]

I pulled out an airport directory I've got here at the house, and it's got the phone numbers listed. ASOS is automated with minute by minute updates. You just call the number, and a robot spits out the info. Your tax dollars at work . Most airports got 'em... Peachtree, Fulton County, Hartsfield, Peachtree City, Newnan, Griffin. Let me know it you want to give it a try.


Rookie2

 

[RavenTai]

Cool

Can I have the #'s for

“Peachtree Falcon Field” FFC , “Newnan Coweta County Airport” CCO, and "Hartsfield" ATL

The first two are pretty close to me, ATL is about 35 miles away but should have the most accurate sensors.

what do you fly?

 

[semlin]

raventai, that's pretty impressive resolution . what kind of camera do you have?

 

[RavenTai]

It is a Nikon coolpix 4500 4.13MP, about 3 years old, overall a very good consumer camera (pro-sumer?) , it has strengths and weaknesses, one weakness is auto focus in low light, one of its major strengths is macro like this, I was literally bumping the lenses into the gauges back light diffuser taking some of those shots. it get even closer if it were not for the body of the gauge getting in the way.

As with anything else electronic you can get a better camera for less money now.

 

[RavenTai]

Here is a pic of the bottom of the gauge with all the markings, only the closer half is the water temp gauge, for the Kanji near the top see this thread

https://forum.ih8mud.com/showthread.php?t=57834

It says “middle temperature stable” or basically “numb gauge”

At the top it has a #

“769916-420”

There are also two stamps in black ink, they are too smeared to fully read but they look like a mix of Kanji and numbers, possibly inspected by ________ ?

The 75 ohm resistor is drawn schematically in the copper sheet but The diode is not represented as it should be with an arrow and bar but instead a rectangle with a stripe at one end, not a way I have seen a diode drawn before.


On the back of the face card at the bottom it says

“YAZIKI METER”

And at the top

TOYOTA
TO

On the face of the card but where it would not be seen installed in the cluster there are 2 numbers

“16”

And

769135-582

 

[semlin]

Wow, if only we'd just removed the gauge and read the kanji on the back we could have saved a lot of posts

it may say "middle temperature stable" in order to be easily differentiated from another similar gauge which does not have that feature. I'm off to explore whether there might be a different p/n in use elsewhere in the world.

 

[Rookie2]

Cool

Can I have the #'s for

“Peachtree Falcon Field” FFC , “Newnan Coweta County Airport” CCO, and "Hartsfield" ATL

The first two are pretty close to me, ATL is about 35 miles away but should have the most accurate sensors.

what do you fly?

Here ya go:

Peachtree Falcon Field ASOS# 770-487-1610
Newnan Coweta County AWOS# 770-254-1617
Hartsfield ASOS# 404-762-1121

You probably know this but just in case, barometric pressure is referred to as "Altimeter" (for altimeter setting) when you call these up.

I fly Cherokee Piper Warriors and Archers out of McGhee Tyson. Pretty simple trainer aircraft. Single 4 cylinder, 180 hp engine, fixed gear, fixed pitch propeller. I'm sure a lot less complicated than your used to working on. What aircraft do you work on again?


Rookie2

 

[landtank]

This is just a hunch based on working with asian designed electronics. So be kind if this is stupid, but they usually tend to design only one part that can be easily munipulated to to become several. As an example, our own driver's power door switche can easilly have auto up by adding a diode and filing the actuator. I have abosutely no electronic training just some seat of your pants trial and error, but I'd pull that resistor out of the circuit and see what happens.

 

[RavenTai]

Semlin, I should have posted that Kanji when I pulled my gauge out for pictures over a year ago.


R2 Thank you for the #'s, thermocouples should be here tomorrow.


We had 3 piper Cherokees at school good plane, one was in 99% shape, beautifully painted, the worst one our structures instructor took a hatchet to and we practiced repaired the damage. Yesterday I was working on a MD-11, on any day I can be on a 737, 757, 767, 777, or MD88,

I may work on them but flying is a demanding task, I got some seat time in a simulator, I can say with confidence I suck at landing planes. I bounced a 767-400 about 500' back off the runway, I don’t think the real thing bounces like that. I spent to much time trying to keep on the glide slop and forgot all the other stuff, even had to be reminded to lower the gear and flaps , I came in way too fast.

Rick, that is about how it is going to go, I know the diode will have to be removed and replaced with a resistor. the value of that resistor is unknown right now but a higher value will give a wider range of readable temperatures on the gauge, the 75 ohm resistor will also likely have to be replaced, that will adjust the center point up or down, right now it would center at ~140F

 

[RavenTai]

Progress report,

Back on this after my trip, (many Coho Salmon in my freezer ) I drilled up the chunk of aluminum, made provisions for feet (made form a relatively low heat conductance metal) that will raise the chunk off the bottom of the pot, this will insulate the element and allow oil to circulate under it. Goal here is to try to have the thermistor and thermocouple read the same temperatures by minimizing uneven heating in the chunk.

On top it has a spot milled for a thermistor, I did not want to try to track down a metric tap for it so instead it is milled for the two diameters of the thermistor and made a clamp to ensure good contact to the aluminum for both heat and as a ground for the thermistor. Three 1/8" holes are drilled for thermocouples at varying depths and a threaded hole for a ground connection.


Also did the boiling water calibration test for the digital thermometer,

I found out my digital thermometer looses the tenths past 199.9, so I don’t get sub degree resolution of boiling point in Fahrenheit but I do in Celsius

Boiling readings were
210F steady
98.8 C to 99.0 C.

Both thermocouples read the same thing at the same time (down to the tenths) , I think the bobbling in the C range was due to convection currents in the water,

Intellicast.com reported 29.99 and rising but that was 1.5 hours behind so no good

All three airports reported 30.23

At 30.23 and 840’ water should boil at 211.0 F / 99.4 C

I’ll call that <1 degree error and good enough for our purposes

I have two days off hope to squeeze in the rest of the test bed build (not much left) here shortly,



Sorry for the delay but could not miss this.

 

[semlin]

if both thermometers read the same and all 3 airports read the same, I'd suspect the medium, but it is close enough for me

btw shouldn't there be a bunsen burner in this somewhere? every experiement I ever did in high school had a bunsen burner.

 

[RavenTai]

Did the first cook tonight, voltage was a little low as I cannot find my battery charger, did I loan that to somebody? Source voltage was 12.29-12.32 through the entire cook. That may slightly move some of the results later but I got some interesting info none the less,

the gauge centers from about 170°F to about 230°F witch is slightly different than Dan’s 93 results, possibly the different gauge part #'s are actually electrically different?

Bottom of the red zone is ~260°F that is dam near where 50/50 coolant mix boils in a pressurized cooling system way to late.

The Zener diode drops .7v foreword bias and breaks over at about 2V reverse bias.

the 75 ohm resistor gets quite hot when reading higher temperatures (higher current than when reading lower temperatures) , the stock resistor is a 2watt, I think I will follow the Miata guy and use 5watt resistors to be safe.

Removing the zener diode but not changing the 75 ohm resistor would yield a gauge that centers somewhere around ~212°F, I would like to move this down to 200 witch means a higher value resistor.

About .6v across the sense coil gets the needle towards either extreme 0V gets the middle

Generic Wally World ATF smokes pretty good at 280°F and stinks bad when hot.

I have a spread sheet with the voltage results but no hosting right now. That is not it would be very useful to anybody else right now anyway.

 

[cary]

Since I don't know enough about circuit design, I was wondering a couple of things:

1) When you remove the zener diode, does that take the dead spot out of the guage? You mention it centers at boiling, that may actually work well, knowing that the line at 1/3 is 190f or so operating temp, middle is 212, and 2/3 line is 230f or so.

2) Can you explain what dropping .7v of forward bias and breaks over at 2v of reverse bias means?

3) If I am correct about #1 could you substitute the zener diode for a different value that still pads the guage slightly (i.e. from 190f-210f) but then allows it to move up?

Thanks

Cary

 

[Rookie2]

Since I don't know enough about circuit design, I was wondering a couple of things:

1) When you remove the zener diode, does that take the dead spot out of the guage? You mention it centers at boiling, that may actually work well, knowing that the line at 1/3 is 190f or so operating temp, middle is 212, and 2/3 line is 230f or so.

2) Can you explain what dropping .7v of forward bias and breaks over at 2v of reverse bias means?

3) If I am correct about #1 could you substitute the zener diode for a different value that still pads the guage slightly (i.e. from 190f-210f) but then allows it to move up?

Thanks

Cary

I'll take a shot at #2, although I only got through chapter two of the circuits book Raven hooked me up on (the library got in Nick Mason's "Inside Out: The history of Pink Floyd", so I've been side tracked the last week).

If you read through Raven's post #54, you should get a better idea of how the diode works. Initially there is a voltage difference across the diode (I presume because of the resistor). The diode allows a certain amount of voltage drop (current flow) forward bias (guage moves), then blocks current flow (guage does not move). As the voltage continues to increase on the opposite side of the diode, it exceeds the voltage on the initial side. Once this voltage difference increases above the capacity of the diode ("break over" point), current flows in the other direction... reverse bias (gauge moves again).

Am I all wet here Raven?


Rookie2