Yet Another DIY JBC

[blueskull]

Being inspired by a few YouTube EE bloggers, I decide to build my own JBC T470 controller.

However, I don't intend to use the same structure used by everyone else (triac controlled mains xfmr).

My goal is to build a small, portable T470 controller that occupies very little space, it better not be bigger than my FX888D.

So, some details of implementation must be different. Here I used a high frequency half bridge converter to regulate power.

Since the bus capacitors on both sides are very low compared with the rated 250W power, the heating element effectively sees only rippling mains frequency AC, therefore PFC is not needed while PF can still be very high.

Also due to the bus capacitance is very small, and the RC/LC constant is far below mains frequency (yet considerably higher than switching frequency, 200kHz), so I can still skip mains cycles to read thermocouple voltage accurately.

The UI is a 2002 character SPI OLED module from Newheven and a rotary encoder with push button. Auxiliary power supply is a Traco 5V power module with very low standby power consumption.