I have a bearing induction heater I use occasionally, its basically a C I transformer core, the primary (3.5kw mains) is on the C section, and the I section is removeable, you slide the bearing over it then place it on the C section, set the time and turn on, the bearing acts as a shorted secondary turn and heats up quickly, and sounds like an angry wasp on steroids.
Later ones have a plug in magnetically attached thermocouple that monitors the temp, then if you cant get back to the heater when its ready at temp it will sit there maintaining temp for you, I'd like to add this function to mine with a microcontroller, as I cant allways be ready to remove the bearing esp on repetitive jobs.
The question is what steps will they have taken to make the system immune from noise, which I suspect is going to be huge from a thermocouple attached to a shorted secondary turn.
I'd have a look inside one I use now and again at another 'shop but it cost £££'s and is pretty much new, knowing me I'd bust it.
Heres the one 'borrow', the connector for the temp rpobe looks like a K type: