An improved electronic transformer for low-power halogen cycle lamps

Halogen cycle lamps are used for both outdoor and indoor lighting although low-power halogen cycle lamps are used in indoor lighting. When lamp power is below 50 W these lamps cannot be connected to power line directly because a low input voltage, between 6 and 24 V, is needed. Traditional supply equipments for low-power halogen lamps are 50/60-Hz transformers, but they are bulky and heavy. A low-cost, reliable, high-frequency supply system (an electronic transformer) for low-power halogen cycle lamps, based on a self-oscillating half-bridge inverter, is described in this paper. Compared with a 50-Hz transformer, weight and size have been minimized. Moreover, a high power factor, more than 0.9, has been achieved, and the circuit is reliable and flexible.