Just bought Quicko T12-952 soldering iron diy set on aliexpress from Quicko official store. It is fine kit and easy to assemble but after powering on a problem occured.
Temperature reading was not steady but sometimes jumps around as much as +- 50 degrees. When set to for example 350 deg. reading was something like 350…349…398…350…299…353…406 and so on.
I was thinking that I’ve made a mistake during assembly or soldering iron controller was faulty. After searching in for anything affecting „Quicko t12 problem” I’ve found this info. It guided me to think about adding filtration capacitor to power supply circuit. Just that capacitor I’v seen in my other soldering station (T13 Bakon).
You need one small 10nF ceramic or tantalum or film capacitor (in any case NOT polarized) marked with „103” number. I’ve used capacitor removed from a cheap old PC ATX power supply. Then solder it to contacts where red and black wires (negative and positive) are connected. It must be placed in handle, not in station enclosure. This should definitely resolve problem with jumping temperature readings.