I want to couple a Hakko 907 soldering iron with PTC thermistor sensor to a generic PID temperature controller. The soldering iron sensor range is approx from 45.9 ohms at zero degrees C to 145.8 ohms at 600 degrees C. The generic PID controller does not support this input but does support PT100. The corresponding range of a PT100 RTD is from 100 ohms at zero degrees C to 313.6 ohms at 600 degrees C. Is it possible to make a circuit which takes the input resistance from the soldering iron sensor and generates the correct output resistance for the PT100? The circuit would have to calculate the output resistance from known variables: input slope, output slope, input resistance at zero degrees C and output resistance at zero degrees C. I've worked out a formula, but I don't know how to go about it.

Any help would be appreciated. I was thinking the circuit may involve a digipot but I don't know the general direction to look or whether it is even possible or feasible.

Thanks in advance.

Hi, Mike.

Can you share a block diagram of the application you have in mind? From what I understand, you want some form of conditioning or conversion of the sensor's resistance that will make it compatible to a temperature controller. The thermistor's output is already in volts, right? If that's so that may be easier for you to manipulate.

You might want to look at the TMP01, a low power programmable temperature controller. Its datasheet contains applications information that may be helpful to you.

Regards,

Karen