| 摘要 |
<p>A switch-mode power supply comprises a D.C. power source (1-13), a transformer with a primary winding (20), first and second switching transistors (22,24) in series with the primary winding, and drive means (30) for generating signals for controlling the switching transistors. On activation of the drive means (30), a diode (44) completes a circuit through the first transistor (22) and part of the primary winding (32) and draws energy from a junction (19A) between two series connected reservoir capacitors (15A,16A). A field is generated in the core of the transformer which is sensed by an auxilliary winding (42) of the transformer which generates a signal. The signal switches on the second switching transistor (24), allowing a circuit to be completed through both switching transistors and the primary winding of the transformer. A rebalance winding (45) is provided to replace energy drawn from junction (19A) to maintain the capacitors in balance. <IMAGE></p> |
