The function of the dimming module

Dimmers based on were inefficient since they would dissipate a significant portion of the power rating of the load as heat. They were large and required plenty of cooling air. Because their dimming effect depended a great deal on the total load applied to each rheostat, the load needed to be matched fairly carefully to the power rating of the rheostat. Finally, as they relied on mechanical control they were slow an. [pdf]