Need help from smart people: creating an "ice warning" LED in the cluster?

Hello,

Me again!

I have seen a few european cars that feature an "ice warning" system. Basically, it's just an idiot light in the cluster attached to some sort of thermometer mounted near the front of the car, and it lights up a blue LED when ice is likely on the road.

I know it seems silly and pointless, but I think it would be cool and unique.

I'm not very handy, especially when it comes to electronics/circuits/etc.

Does anyone know what parts I might need to assemble something like this? Also, if anyone is familiar with these systems on other cars, what temperature do you think would be a good temp to set as the trigger for the warning light...maybe around 38 deg F?

Any info is appreciated. Thanks!

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

I would use something like a Basic Stamp micro-controller. Write a program that kicks on the blue LED when the temp gets below whatever temp you like. It will probably cost you around $200 to implement for a Basic Stamp, blue LEDs, and a temperature probe.

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

Just throwing this out...but...wouldn't you want it to come on closer to 32* since that's the point where water freezes? :dunno: Maybe 33 or 34*?

Look for Fitch or 5-90 to chime in on this one...maybe even PM them. I think they seem to be the electrical brains here. Also, I don't know for sure, but I would think that you could find some kind of temperature operated switch at Radio Shack or somewhere like that. If so, it seems like it would then just be a matter of wiring the light to the "on" position for the switch. Almost like a temperature operated relay. I would think those exist....but again...:dunno:.

You will probably get flamed by some no here but I think it's kind of a cool idea and it would be unique. If this could be done cheaply enough...I might even do it to mine since I am constantly up in the northern NC mountains in the winter.

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

My XJ's thermometer seems quite accurate--I consider seeing 32* on the read-out a sufficient warning as to the possible icing of the roadway surface.

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

mecompco said:

My XJ's thermometers seems quite accurate--I consider seeing 32* on the read-out a sufficient warning as to the possible icing of the roadway surface.

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Yeah but some of us don't have that. I've had them in the past and yes, that is sufficient and has always seemed very accurate.

Just in the 5 minutes I've been researching through google, I've found several promising links. Search for "temperature operated switch" and "temperature operated relay". I think this can be done. I'll let you know what I can come up with. Now that I'm thinking about it, this is basically like a coolant temperature switch or something along those lines. I did find a "temperature switch" that you wire to a relay and this would work, BUT it's $160. It looks just like the coolant temp switch that is in the head on the 4.0 engine only it's longer. I think the battle here will be finding one that isn't $160 and is either adjustable or already set for 30-something degrees.

Look here, < http://www.directindustry.com/industrial-manufacturer/temperature-switch-72329.html > you might find something.

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

You can probably do it without the BASIC Stamp - just a discrete circuit with an air temperature sensor of the appropriate setting or range, an LED of sufficient size and brightness, and a current-limiting resistor.

N.B. - put your sensor in a "dead air" pocket, or the wind chill from forward motion will give you a false response. This is the opposite of the typical fluid sensor (which wants full flow for accurate readings,) but wind chill from a 60-70mph headwind is going to screw up your readings...

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

5-90...I knew you would chime in!

So, for the somewhat electrically declined, can you elaborate on the "discrete circuit with an air temperature sensor of the appropriate setting or range, an LED of sufficient size and brightness, and a current-limiting resistor"

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

BruceB83 said:

5-90...I knew you would chime in!

So, for the somewhat electrically declined, can you elaborate on the "discrete circuit with an air temperature sensor of the appropriate setting or range, an LED of sufficient size and brightness, and a current-limiting resistor"

Click to expand...

Easy. Find a temperature sensor with the setting or range you want that can switch low currents at 12VDC (start with Mouser or Allied, I think, and you should find a few. NewarkInOne is also a possibility. Google-Fu all three.)

You can use a fairly light wire to get the parts connected - 18AWG would probably be overkill, but it's easy to find 18/2 and 18/3 at the hardware store, and having your wires enclosed as a single cable will help you run them about.

For your LED, use a high-brightness LED of whatever colour you like, probably a T1-3/4 or better size. Should be readily available (electronics supply houses, or the sources given above. Particularly Mouser or Newark - since they do more "technical" electronics. Allied is a more "industrial" source. I've used all three...)

The current-limiting resistor is a simple calculation - find out what the nominal operating current of the LED is, and apply Ohm's Law (http://www.the12volt.com/ohm/ohmslaw.asp - a nice chart/image/whatever and a batch of calculators here. Click on the pie chart for calculators.) Select whatever resistor is closest to what you calculated, and put it in series with the LED.

For the sensor mounting, keep it away from potential heat sources (probably at the end of the bumper will serve) and out of forward wind (I'd probably put it at one end, behind the endcap.) This will keep wind chill from giving you "false positives" (wind chill) or "false negatives" (engine heat.)

Civil Service Exam - Question #1. "How do you put a giraffe in a refrigerator?"

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

you can have ice on the road before it ever gets to 32°. when i lived in northern ohio and southern michigan we would start getting black is when the temps hit 35°... water freezes when IT gets to 32° not when the air does.

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

GrimmJeeper said:

you can have ice on the road before it ever gets to 32°. when i lived in northern ohio and southern michigan we would start getting black is when the temps hit 35°... water freezes when IT gets to 32° not when the air does.

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True.

How do you fit a giraffe into a refridgerator??? Open the door and put it in. How do you get an elephant in the refridgerator? Open the door, take out the giraffe, and put the elephant in.

You doubted me didn't you. I'll even go further...

The Lion King is hosting an animal conference. All the animals attend except one. Which animal does not attend? The elephant, he's still in the refridgerator.

There is a river you must cross but it is used by crocodiles, and you do not have a boat. How do you manage to cross it? Jump in and swim across. All the crocs are at the conference.

This is a common questioning in accounting/finance consulting or public accounting interviews. They learned us that in business school.

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

BruceB83 said:

True.

How do you fit a giraffe into a refridgerator??? Open the door and put it in. How do you get an elephant in the refridgerator? Open the door, take out the giraffe, and put the elephant in.

You doubted me didn't you. I'll even go further...

The Lion King is hosting an animal conference. All the animals attend except one. Which animal does not attend? The elephant, he's still in the refridgerator.

There is a river you must cross but it is used by crocodiles, and you do not have a boat. How do you manage to cross it? Jump in and swim across. All the crocs are at the conference.

This is a common questioning in accounting/finance consulting or public accounting interviews. They learned us that in business school.

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Pity they don't teach that in primary schools anymore. I think that was a test for us around fifth grade in something-or-other (I don't recall what.) I still think it's a good test - but the way most people are taught these days, they wouldn't pass...

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

With regard to wind chill. I beleive only warm blooded living things are affected by wind chill, not all objects.


Jim

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

wjp said:

With regard to wind chill. I beleive only warm blooded living things are affected by wind chill, not all objects.


Jim

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Nope - everything is affected by wind chill, if it is able to transfer heat. Why do you think you can cool off soup by blowing on it?

"Wind chill" is a simple name for a process - by allowing more air to flow past something, you give it more of an ability to transfer heat energy into the air (because you don't have "heat saturated air" over and around it.) "Wind chill" is what makes your radiator work. "Wind chill" is part of what makes your refrigerator work (although that's air circulation by convection, not any sort of force.)

If you've got a constant supply of fresh air (or other fluid) flowing over something that has a higher heat content than the air, the heat content of the object will reduce at a greater rate than it would in still air. "Wind chill" is just the catchy name that weathermen have tagged it with - but it's a basic process of heat transfer, and it affects anything that contains heat. We just happen to notice it because we generate our own heat (in a literal thermodynamic sense, a human being is little more than a heat engine) and we note that we get tired when we have to generate more heat to maintain a working core temperature - cf. "hypothermia."

That's why it's possible for a lake to start freezing over with an ambient temperature of almost forty degrees Fahrenheit - but a wind chill of nine degrees cooling. The effective temperature over the water has become thirty-one degrees Fahrenheit, and the water will start to freeze - especially if it's still. (And don't tell me it's impossible, because I saw it happen when I was younger.)

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

5-90 said:

Nope - everything is affected by wind chill, if it is able to transfer heat. Why do you think you can cool off soup by blowing on it?

"Wind chill" is a simple name for a process - by allowing more air to flow past something, you give it more of an ability to transfer heat energy into the air (because you don't have "heat saturated air" over and around it.) "Wind chill" is what makes your radiator work. "Wind chill" is part of what makes your refrigerator work (although that's air circulation by convection, not any sort of force.)

If you've got a constant supply of fresh air (or other fluid) flowing over something that has a higher heat content than the air, the heat content of the object will reduce at a greater rate than it would in still air. "Wind chill" is just the catchy name that weathermen have tagged it with - but it's a basic process of heat transfer, and it affects anything that contains heat. We just happen to notice it because we generate our own heat (in a literal thermodynamic sense, a human being is little more than a heat engine) and we note that we get tired when we have to generate more heat to maintain a working core temperature - cf. "hypothermia."

That's why it's possible for a lake to start freezing over with an ambient temperature of almost forty degrees Fahrenheit - but a wind chill of nine degrees cooling. The effective temperature over the water has become thirty-one degrees Fahrenheit, and the water will start to freeze - especially if it's still. (And don't tell me it's impossible, because I saw it happen when I was younger.)

Click to expand...

The temp probe in the car will read the same temp as outside. If the outside temp is 35 degrees and you start driving at 10 mph the temp is still going to read 35 degrees. If you drive at 90 mph the temp is still going to read 35 degrees. The temp probe is going to stay the same temp as the current outside temp, regardless of wind speed.

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

Probably because the temp sensor for the temp probe is in a place where it is not affected by wind speed, such as behind the bumper as suggested...

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

i almost have to agree with wjp... if there was a something evaporating off of the thermometer then it would read wind chill, but if it is dry then there is no medium for the heat energy to disperse with. kind of like sweat in the summer with a breeze... you dont sweat you wont feel much cooler even with breeze. and a refrigerator/ air conditioner works by compression/decompression.... the radiators on both are to assist in the heat dispersial caused by this opperation... and the radiator on a car thing... air that is a cooler temperature than the radiator moving through it is cooling it by attempting to bring it to ambient temperature. if the air was the same temps as your coolant then you would have no cooling effect.... no matter how fast you are going. oh and you cool soup by blowing on it because it speeds up heat loss through evaporation(steam) , and keeps fresh cool ambient air moving over it, preventing the air around it to heat up and slow the cooling process.

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

but boy have we strayed from the original post.

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

I see your logic, and must say, it would be easy to agree with, but I still don't. I don't know why, I just don't feel like the argument has been made to overturn my original thought. What tool do you suppose the weather man uses to calculate the wind chill factor? A sweaty arm?

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

dgrigorenko said:

but boy have we strayed from the original post.

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Not really, I think we are still talking about how to make an ice warning thingamajigger. We are simply covering how to make it accurate. I say it is important and contributing information.

Re: Need help from smart people: creating an "ice warning" LED in the cluster?

wind chill is calculated with a formula not a guage of some sort:
For the mathematically minded, one formula in pseudo code for wind chill temperature tc is

• • Windchill (ºF) = 35.74 + 0.6215T - 35.75(V^0.16) + 0.4275T(V^0.16)
    Where: T = Air Temperature (F)
    V = Wind Speed (mph)
    ^ = raised to a power (exponential)
    Windchill Temperature is only defined for temperatures at or below 50 degrees F and wind speeds above 3 mph. Bright sunshine may increase the windchill temperature by 10 to 18 degrees F.

or go to http://www.weather.gov/os/windchill/index.shtml