| 摘要 |
PURPOSE:To obtain a power supply circuit that produces a stable output over a wide range with simple constitution, by varying the puluse duration of the output wave so as to ensure an adverse proportion to the output voltage of an AC-AC converter and as a result setting the effective voltage at a constant level. CONSTITUTION:The voltage of an input commercial power supply, etc. is applied via a rectifying circuit D1 of an AC-AC converter, and a current of a waveform having a pulse duration T is delivered by a capacitor C1. Then transistors TRQ1 and Q2 are alternately turned on via output transformers T2 and T3 to which the pulse of duration tau is applied alternately from a control circuit A. Thus a current varying its direction alternately is supplied to a primary winding L1 of the transformer T1. Then the effective voltage Erms=(tau/T)XE is generated from a secondary winding L2 of the T1, where E is the input voltage. On the other hand, the rectifying circuit of the circuit A varies the tau/T in adverse proportion to the changing factor of the voltage E. As a result, the voltage Erms has no change and is set constant to obtain a power supply circuit of a slide projector that generates a stable output over a wide range with a simple structure. |
