I also pulled this out of the skip. It's obviously a speed controller, 240V. It puts out 240V for all but the first 30 degrees of the control knob's travel. AIUI some speed controllers don't put out full power except when turned up to maximum. Could I use this to control the speed of a pillar drill, bearing in mind the limitations of cooling the motor caused by slow running and the resultant lack of airflow. Are there other reason why slow running motors heat up?