Makes sense, turns out my problem was that the heater was inductive and I didn't have a snubber on it. I was using the AD8495 only because I made a controller for an old solomon iron I had and was trying to adapt that controller to work with these T12 tips however I guess that isn't going to work and I'll just design a new analog frontend for the thermocouple. Thanks for your help.
Thanks for the response, I guess I should have read the original post more closely as it does mention that the thermocouple is in series with the heater. After some testing last night I came to the same conclusion. My question is how are you supposed to measure it when it is setup this way. I am running a AD8495 for reading the thermocouple voltage. If i put a couple of diodes to ground with isolating series resistors I can limit the voltage input to it when the power is applied but it still doesn't read properly unless I completely disconnect the ac lines from it. Should the AD8495 be run without a ground reference, I currently have a 1M to ground on the inverting pin.
The connector from digikey that I mentioned above is an exact match for the hakko plug, I have it already and can confirm this without a doubt.
Does anyone know what the pinout for the FM-2027 is? I would like to try this out and ordered a handle from hakko but I have no idea what connections are what and there are 8 pins on this thing. Found the two I think are the heater because it measure around 9 ohms between them but where would I read the thermocouple from. I assume some of the other pins are for detecting removal of the tip. I read this whole thread but nobody mentions the pinout for this thing. Also if anybody is looking for a connector for the FM-2027 the Digikey part number 361-1267-ND is the matching female connector.
