Dewalt screen speed control

Has anyone ever seen this
Basically it’s running a router like we use off of a variable dc power supply, they say it makes it run cooler and quieter.
I don’t know a whole lot about ax/dc power for motors, so if anyone has any advise before I build one I’m all ears

A few of us use something very similar to what is linked at the end of that thread. mine At hf. Been running for a couple years now

Is the harbor freight one putting out Ac or dc voltage? If the diagram is the same as the router speed control they link to I would just buy one.
Also is there much difference between the Frankin speed control and the harbor freight one?

I’m not positive but pretty sure the hf speed control uses a triac circuit with a variable resistor to control the chopping frequency. A triac is two rectifiers back to back so it would function kind of like an adjustable version of what’s described in the link.the hf version is a better implementation though and just as cheap as building yourself, especially if you have a 20% off coupon