Hello, in my espresso machine repair business I frequently replace 10K NTC boiler sensors on small automatic coffee machines. These are LUG 5M SENSORS and they go bad quite OFTEN, probably because the boilers regularly exceed 150 degrees C when steaming, which for most of these sensors is their upper capacity. So I have been using used OEM sensors for this, but even used are hard to get, and new are too expensive so I went to Digikey to see what they have and they DO have Vishay Lug 5M bolt on sensors - NTCALUG54A M5 to be exact however the temperature curve is significantly different. At boiling 100C the OEM ones measure .7K ohms and the Vishay are like 1.1K Ohms. However...the VISHAY seem to work, the Espresso machine with the VIshay sensor creates either hot water or steam as requested and does NOT put up any error message (like it would for a failed sensor) but does this mean we are good to go here? I do not see any other lug sensors with different temperature curves to even choose from. The boilers are protected with thermal fuses so there's no serious hazard if something goes wrong .......but again.......many questions abound. Will they go bad sooner? Perhaps work just fine? I have no idea. The limit of my electronics knowledge is basic use of a multimeter to measure things only.
The interesting question here is HOW do electronic boards determine exactly WHAT the termperature is with an NTC sensor? Do they correlate the exact resistance to some embedded database table? Or is it some general scale times some multiplier? Hmmmm. Ideally, I would want the replacement NTC sensor to measure .7K ohms at 100C! Is this NTC sensor available on Digikey? I do not know how to search for it! I am not about to construct a temperature curve for my OEM sensor to compare! All responses appreciated.
The interesting question here is HOW do electronic boards determine exactly WHAT the termperature is with an NTC sensor? Do they correlate the exact resistance to some embedded database table? Or is it some general scale times some multiplier? Hmmmm. Ideally, I would want the replacement NTC sensor to measure .7K ohms at 100C! Is this NTC sensor available on Digikey? I do not know how to search for it! I am not about to construct a temperature curve for my OEM sensor to compare! All responses appreciated.