| 摘要 |
PURPOSE:To facilitate the design of a transformer and the selection of a transis tor by directly detecting a collector current to control a base current. CONSTITUTION:A power source circuit of ringing choke type 1-element transistor self-excited oscillation type power source circuit turns ON and OFF the DC voltage EDC of an external power source 1 by a switching transistor (Q1) 4 to supply energy from a transformer winding 7 to a load resistor 8. In this case, a resistor 9 for detecting the emitter current of the Q1 4 and a transistor (Q2) for controlling the base of the Q1 4 by the detected output are provided. Thus, when the voltage across the resistor 9 arrives at the threshold level of the Q2 10, it is conducted, the base current of the Q1 4 is interrupted and can be inverted. Thus, the maximum collector current of the Q1 4 can be freely set by selecting the resistance value r3 of the resistor 9, and the design can be facilitated. |
