| 摘要 |
PURPOSE:To prevent the breakdown of an element, which controls an output transistor that is used in the power source circuit of a dead weight meter for a truck, due to a surge voltage, by connecting the power source terminal of the element, which controls the output transisor of a power source stabilizing circuit, and the output terminal of the power source stabilizing circuit. CONSTITUTION:A power source terminal 44 of an operation amplifier 42 is connected to the emitter of an output transistor 41, i.e., the output terminal of a power source stabilizing circuit 40. A Zener diode 47 and a resistor 48 are used to apply a voltage, which is obtained by increasing the output voltage of the operation amplifier 42 by a specified amount, to the emitter of the transistor 41. The output voltage of the operation amplifier 42 is required because it is lower than the voltage, which is required to control the transistor 41. Therefore, the Zener diode 47 can be substituted by a resistor. Even though a surge voltage is generated, the surge voltage does not reach the parts after the collector of the output transistor 41. Therefore, the operation amplifier is not broken down by the surge voltage. |
