Temperature controller for DIY heat treat oven

I am getting ready to build Heat treating oven for my O-1 and 440C knife blades. I found a good digital temperature controller on eBay. But it has RTD input - not thermocouple input. Can anybody explain me the difference?

BTW Temp in my oven will go up to 2200F

Thanks, Alex

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Check: http://www.omega.com/techref / Tons of good information on both.

RTD's have too low a temp range for your oven. Your probably going to need to get a controller that uses a "K" type thermocouple. There are other thermocouple types that cover your temp range, but the "K" is the cheapest...to my knowledge.

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On 11 Nov 2005 14:38:46 -0800, the renowned "Alex"

That's really high for an RTD. I don't like using them much above 400C.

An RTD is a coil or a thin film of a metal or alloy (often platinum) that changes resistance with temperature. They tend to be much more stable at relatively low temperatures than thermcouples and they require no cold-junction compensation (which tends to further improve accuracy at temperatures near room temperature).

If you're in the States or Canada, hold out for a type K thermocouple-input controller, if in Europe consider type N.

Best regards, Spehro Pefhany

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Alex wrote:

The other guys explained the differences but double check the controller specs. Most of the brands I've used can be configured for just about any input type with the internal jumpers.

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RDT's are usually used for process control in the temperature range -20 to 100 Deg C . They are used in the food and process industries because of their reliability and accuracy at these temperatures. It is unsuitable for the much higher temp of your oven. Many of them can either be re-configured for thermocouple use or have a thermocouple module installed. call the manufacturer for more details.

Tom

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