I need a circuit same as Lamp Dimmer... I need to control the RMS of 220VAC to have the voltages range around 0~220Vac using potentiometer as my controller..
I had some idea using SCR or TRIAC but not sure if it would hold around 220VAC.
I wouldn't worry about the top-end of the range but about the bottom ..
After all, firing pulse is applied to the gate of the triac and consequently the triac conducts only when the voltage riches certain threshold (the TRIAC is triggered when the Live is about 30V) .. see attached example .. or: https://kitsrus.com/pdf/k19.pdf
There is another type of dimmer that is most frequently used in commercial applications, for example, lighting of the theater - this method uses an autotransformer instead of a triac ..
You can't have better voltage/power regulation than that and the full range is covered: from 0Vac to 230Vac (or whatever) ..
Telling the exact application would actually ease making precise suggestions. A good standard dinmmer circuit as given by IanP
may or may not work, depending on the load type. An autotransformer (or variable isolation transformer) will in contrast
always work and would be my preferred method in the lab. But it's not controlled by a potentiometer. The said theater lighting
controllers (I have seen them last in about 50 years old installations) have servo motors for it.