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本文介绍的直流放大器是为离子检测器设计的,它既可在普通实验室里使用,也可作现场测量用。这种放大器电路采用商用集成电路组装而成。前置放大器(见图)是电路的关键部分。前置放大器基本上是一个电流放大器。电流加在运算放大器A_1的反相输入端。反馈环路使得输入电阻变得很小,输入电压对地只有几毫伏。前置放大器的输入过载保护采用了2N5909结型场效应晶体管,这种器件具有双向极性保护功能。在
This article describes the DC amplifier is designed for ion detectors, which can be used in general laboratories, but also for field measurements. This amplifier circuit using commercial integrated circuit assembly. The preamplifier (see picture) is a key part of the circuit. The preamplifier is basically a current amplifier. The current is applied to the inverting input of op amp A_1. The feedback loop makes the input resistance very small, and the input voltage is only a few millivolts to ground. Preamplifier input overload protection using 2N5909 junction field effect transistor, this device has bidirectional polarity protection. in