| 摘要 |
PURPOSE:To prevent transistors from being broken by overcurrents by a method wherein switching transistors for suppressing the overcurrents are connected to each pair of transistors on one side, in a forward and reverse rotation circuit with a transistors bridge. CONSTITUTION:A bridge circuit is formed using four transistors 5-8, switching transistors 11 and 12 are connected between bases and emitters of the transistors 7, 8 on one side out of the transistors 5, 7 and 6, 8 respectively making a pair, in the forward and reverse rotation circuit in which the DC motor 9 is connected between one side terminals of the bridge circuit, and the bases of the transistors 11 and 12 are connected to collectors through resistors 13 and 14, respectively. If the DC motor 9 stops and overcurrent flows for some reason, the switching transistor 11 or 12 is made continuous and a continuity degree of the transistor 7 is decreased to effect suppression of the current. |
