Re: Really universal soldering controller Reply #5430 – August 08, 2021, 09:07:45 am Quote from: afedorov on August 07, 2021, 11:16:02 pmadmaverick, minkok, it's much easier to just implement auxiliary DC supply, rather than messing with values and dropping 30-odd Volts on Q1.If I was going to redesign the power board to support higher voltage irons, I'd use 12V supply and get rid of Q1 and Q13 circuits all along.It could be a separate 3W AC-DC supply, like IRM-03-12 or separate 9VAC transformer winding with it's own rectifier and filtering. If you have a toroidal transformer, just wind a turn on top and measure the voltage on it, then wind the remaining.I totally agrees with you afedorov regarding the auxiliary 12v supply. Unfortunately, per Sparkybg's current design, you have to keep the valley fill circuit near Q1 in order to minimize switching noise around zero crossing. I am planning to do a revamp of Unisolder using STM32 instead of PIC32 and will be all modular design (i.e. you can swap in different power board for different applications while keeping the MCU board).