Since I consider this project finished now and I had this in use for a few month now, I guess its time to do a little summary of the features
Supported soldering irons
So far I only tested this with a JBC NT115 hand piece, but it should work for all soldering irons where the heater is powered through the thermocouple. This is certainly a minority of the available soldering irons though, since most have a separate wire for power. But I think some Hakko tips use the same design as well. If you intend to use a different iron with a different thermocouple, keep in mind that you may have to adjust the gain for the thermocouple amplifier.
Since I didn't include a separate power supply for the gate driver, the maximum voltage is limited by the gate driver and the maximum gate voltage of the used mosfet. I run this at 12V and you shouldn't go much higher. This would be easily changeable, but since I designed this for low-power irons it never was a problem.
- Highly responsive temperature regulation for almost instant heat-up.
- Two levels of standby/sleep modes controlled by a contact closed when the hand piece is in the holder (Could be a micro-switch or a contact closed between the sens line and the metal ring of the hand-piece).
- Target temperature will be dropped to standby temperature as soon as the hand piece is in the holder.
- After a delay the heater will be turned off completely.
- Idle detection turns off the heater when the iron is not in use for some time but not in the holder.
- Menu implementation on the display to set controller / standby parameters.
- Persistent storage for all settings, including the current set temperature.
The enclosure I designed for this project is very basic and leaves lots of room for improvement. It's very light, so it doesn't feel high-quality at all. On the up-side, it is super compact while still having an integrated holder for the iron.