Abstract: A high leakage reactance transformer especially for current limited control of gas discharge lamps and other electrical discharge loads has a core with three legs defining two magnetic loops. A first leg has an air gap with a fixed reluctance, a second leg is common to both loops and has a primary winding, and the third leg has a supply winding for connection to the discharge device as well as a control winding connected to a control circuit. The control winding has an adjustable load to vary the reluctance of the third leg and control the current limit of the supply winding. Linear and proportional control circuits are shown.