I am thinking to use the very good JBC tip for some project and was looking at the net for the details about the tips but have not found what i need.
What is the pinout on them??
I repost this image from another thread here cos I can't be bothered to find it again.
The heating element is about 2.4 ohms cold. The wire in a 245 hand piece is skinny 3 cores and about 0.12 ohms each.
Not sure anyone knows exactly what the thermocouple is. Probably Nichrome is used for the heater element and one side of the thermocouple. The other side could be anything, possibly stainless steel maybe Nisil making it close to an N type. Another problem is the cold junction will be the other end of the cartridge which gets warm.
JBC drive the heater with full half mains cycles at about 24v. They put about 170W into the heater during warmup. I am pretty sure the heater is driven through the thermocouple.
I have considered the design of a controller for these cartridges and it isn't simple to do it properly. JBC measure the thermocouple during what looks like about 30uS of dead time around mains zero crossing.
Someone in one of the other threads was making a controller but I don't think anything was posted recently - he probably discovered it isn't simple.