originally for a 100-watt soldering iron, I took with a margin of another 1900 watts, for growth, so to speak
I.e, . I stuffed it into the case from the universal power supply unit of the laptop. 
Motors
I decided to try the regulator on different devices. It easily controls the speed of brush motors, it is a grinder, grinder and other brush motors, which are not very dependent on the frequency of the network.
The shaft of the grinder can be made to spin very slowly, but remember, if it breaks, high speeds can suddenly turn on! (they told me that).
As for asynchronous motors, the controller cannot control them. They either work from a certain threshold or not. If they don’t work, then they stand and buzz. After starting, the speed does not decrease either. I tried to start the pump with an asynchronous engine.
Power supplies
He included a switching power supply for the laptop with an output of 18V, it also either works or not. To such a unit, I connected a drilling machine from a 12V screwdriver. Turnovers are not regulated.
But the step-down transformer 220 / 12V works, that is, you can control the power at the 12V output by controlling a trans through a dimmer.
Light bulbs
The LED light flashes at a certain frequency, which is adjustable. Well, the incandescent should burn just dim (not checked).
conclusions
does something with the frequency, which is exactly, I don’t know, but on the example of a vibrating grinding machine I found four thresholds for changing the frequency, you can watch / listen to the video. Perhaps he "cuts" AC waves.