The speed of most AC motors cannot be reliably reduced with the simple motor speed controls that might otherwise work well to dim lights or reduce the speed of small fan motors. Lights (incadescant) and some small motors (universal AC) can operate with reduced voltage/power but the RPM of most AC motors is determined by the incoming frequency and number of poles - minus a little bit of slip. In order to change the RPM or speed the frequency of the incoming power must be changed.
Any of those circuits will do, just double the voltage rating of the components. Your chinese dremel is no doubt a universal motor. It will run on AC or DC. If it has replacable Brushes, it is a universal motor. For a check, apply a low DC voltage and see if it turns.