12VDC thermostat switch?
06-23-04, 06:01 PM
#1
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12VDC thermostat switch?
Anyone know where I can get an adjustable 12V thermosensor switch? I have several applications in development that could use this. I need 1 to sense air intake temps and be able to send a signal (+ or -) to a relay when a set temp is reached.
I need another to sense the temperature in the cabin of the car. I have been searching google and some other sites, but no luck so far.
any ideas? btw, I have no idea what section to put this in.
thanks.
I need another to sense the temperature in the cabin of the car. I have been searching google and some other sites, but no luck so far.
any ideas? btw, I have no idea what section to put this in.
thanks.
06-23-04, 06:17 PM
#2
No it's not Turbo'd
I would look for the word thermocouple.
By defenition a thermocuple returns a voltage based on the temperature, it's a variable resitor or Pot, by the way it operates, in that there are some where current goes up as temp increases, to a fixed point. But in most Voltage decreeases (Resistance increases) across the range of the thermocouple, as temperature increases. Once yout know the voltage that corresponds to the value you want to take action, pick a relay that sits slightly above that value and then pick a resistor to bring it to exactly that vlaue so the switch toggles exactly at your predefined value. To add adjustability add another rotray pot (Potentiometer) instead of a fixed resitor, and dial in a resistance untill you hear the relay click.
That way you can later adjust this to compensate for tuning purposes or other enviromental conditions, or age of the thermocouple.
They come in multiple flavors, some, for extreme temperature ranges. An EGT is nothing more than an example of this at the High end of extreme.
By defenition a thermocuple returns a voltage based on the temperature, it's a variable resitor or Pot, by the way it operates, in that there are some where current goes up as temp increases, to a fixed point. But in most Voltage decreeases (Resistance increases) across the range of the thermocouple, as temperature increases. Once yout know the voltage that corresponds to the value you want to take action, pick a relay that sits slightly above that value and then pick a resistor to bring it to exactly that vlaue so the switch toggles exactly at your predefined value. To add adjustability add another rotray pot (Potentiometer) instead of a fixed resitor, and dial in a resistance untill you hear the relay click.
That way you can later adjust this to compensate for tuning purposes or other enviromental conditions, or age of the thermocouple.
They come in multiple flavors, some, for extreme temperature ranges. An EGT is nothing more than an example of this at the High end of extreme.
Last edited by DCrosby; 06-23-04 at 06:22 PM.
06-23-04, 06:21 PM
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Originally posted by DCrosby
I would look for the work thermocouple.
By defenition a thermocuple returns a voltage based one the themp, it's a variable resitor or Pot, by the way it operates, in that there are some where current goes up as temp increases, to a fixed point. But in most Voltage decreeases (Resistance increases) across the range of the thermocouple, as temperature increases. Once yout know the voltage that corresponds to the value you want to take action, pick a relay that sits slightly above that value and then pick a resistor to bring it to exactly that vlaue to the switch toggles exactly at your predefined value, to add adjustability add another rotray pot (Potentiometer) instead of a fixed resitor, and dial in a resistance untill you hear the relay click.
I would look for the work thermocouple.
By defenition a thermocuple returns a voltage based one the themp, it's a variable resitor or Pot, by the way it operates, in that there are some where current goes up as temp increases, to a fixed point. But in most Voltage decreeases (Resistance increases) across the range of the thermocouple, as temperature increases. Once yout know the voltage that corresponds to the value you want to take action, pick a relay that sits slightly above that value and then pick a resistor to bring it to exactly that vlaue to the switch toggles exactly at your predefined value, to add adjustability add another rotray pot (Potentiometer) instead of a fixed resitor, and dial in a resistance untill you hear the relay click.
Im not smart enough to understand what all that means, but damn it sounds impressive....
I was kinda hoping for a linky for a switch. I know someone has to know where..Im just a googling it.
BTW, thank you very much for that write up, im just looking for something a little more simple
06-23-04, 06:24 PM
#4
No it's not Turbo'd
Is a Manufraturer
http://www.omega.com/toc_asp/section...ture§ion=a
http://www.omega.com/toc_asp/section...ture§ion=a
06-23-04, 06:31 PM
#5
No it's not Turbo'd
Okay a relay is nothing more than a switch, that is operated by a low amperager (danger/battery draw) cuircuit, that throws the switch for a High Amperager (danger/draw) cruircuit. Provided there is enough Voltage to energise the magnet to throw the switch.
Simpler.... Switch something else on as long as the first thing has enough voltage.
Finding what that "Enough Voltage" is depends on the Thermocouple. If your thermocouple is 0-1000 degrees @ 0-12v for simplicity, then it stands to reason that if the thermocouple reads 500 degrees the voltage should be 6v, and a 12v relay would not activate. Yet a 6v relay would. But could also overheat, should you send it 12v @ 0 degrees. So be carefull, and maybe test this whole thing with a car battery before you install it.
And there's another problem, you'll need an inverter, since @ 0 degrees the 6v relay will be "On" and at 750 degrees the 6v relay will be off, while you probhably want the opposite where the relay is off untill a certain temp is exceeded. You might be better off buying a cuircuit that allready has this fuctionality, as part of the termocouple.
This might be more usefull.
Search for Thermoswitch resulted in:
http://www.gaumer.com/ProductFilter....nwal17000therm
Simpler.... Switch something else on as long as the first thing has enough voltage.
Finding what that "Enough Voltage" is depends on the Thermocouple. If your thermocouple is 0-1000 degrees @ 0-12v for simplicity, then it stands to reason that if the thermocouple reads 500 degrees the voltage should be 6v, and a 12v relay would not activate. Yet a 6v relay would. But could also overheat, should you send it 12v @ 0 degrees. So be carefull, and maybe test this whole thing with a car battery before you install it.
And there's another problem, you'll need an inverter, since @ 0 degrees the 6v relay will be "On" and at 750 degrees the 6v relay will be off, while you probhably want the opposite where the relay is off untill a certain temp is exceeded. You might be better off buying a cuircuit that allready has this fuctionality, as part of the termocouple.
This might be more usefull.
Search for Thermoswitch resulted in:
http://www.gaumer.com/ProductFilter....nwal17000therm
Last edited by DCrosby; 06-23-04 at 06:38 PM.
06-23-04, 07:55 PM
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thanks, im gonna check out your link. I found this:
http://www.rparts.com/Catalog/Major_...s/controls.asp
Its a 12 VDC adjustable thermostat. It looks pretty cool.
http://www.rparts.com/Catalog/Major_...s/controls.asp
Its a 12 VDC adjustable thermostat. It looks pretty cool.
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06-23-04, 08:36 PM
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Originally posted by rockshox
get an LM34 temp sensor, an LM2940 voltage regulator, a pot, and an LM2903 comparator and put them together.
get an LM34 temp sensor, an LM2940 voltage regulator, a pot, and an LM2903 comparator and put them together.
06-23-04, 08:39 PM
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uh yeah. its really pretty simple if you just read a little bit. stop making smartass comments and playing dumb and maybe you could acomplish something. i gave you all the pieces for making a nice adjustable pre calibrated accurate to 1 degree temp switch.
06-23-04, 08:41 PM
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Originally posted by rockshox
uh yeah. its really pretty simple if you just read a little bit. stop making smartass comments and playing dumb and maybe you could acomplish something. i gave you all the pieces for making a nice adjustable pre calibrated accurate to 1 degree temp switch.
uh yeah. its really pretty simple if you just read a little bit. stop making smartass comments and playing dumb and maybe you could acomplish something. i gave you all the pieces for making a nice adjustable pre calibrated accurate to 1 degree temp switch.
I asked for a Switch to BUY, not to build. Im not an electrician and I can afford to buy one complete.
I think I found it anyway. thanks for your input, someday maybe i'll put the pieces together after im done with my field trip to the electric company.
06-23-04, 08:55 PM
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after I run my a/c for about 20 minutes or so I get frost building up on my vents and my car starts to look like a walk in freezer (the white frozen air) so I want a switch to regulate the compressor.
06-23-04, 09:05 PM
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Originally posted by teamstealth
wow i envy you...your a/c blows cold
wow i envy you...your a/c blows cold
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12dc, 12v, 12vdc, 2002, ac, adjustable, chevrolet, control, dc, lm2903, relay, sale, switch, thermocouple, thermostat
