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光电FET可以用作一只可变电阻,或与一只固定电阻一起用作电位器。H11F3M光电FET有7.5kV的隔离电压,因此能够安全地控制高压电路参数。但这些器件的非线性传输特性可能成为问题(图1)。为了校正这种非线性,可以采用一种简单的反馈机制,使电位器产生一种线性响应(图2),本电路使用了两只光电FET,一只作反馈,另一只则用于需要隔离电位器的应用。将两只光电FET的输入端串联,就可以保证输入LED有相同数量的电流。FET输出端放50kΩ的电阻,以模拟电位器的响应。电路对设定输入电压(用电位器R7调节)和光电FET1的反馈之间的差值做放大。得到的输出控制光电FETLED中的电流,直到反馈电压等于输入电压时为止。输出电压以线性方式跟随输入电压(图3)。也许你会认为相同器件号的光电
Phototransistors can be used as a varactor or as a potentiometer with a fixed resistor. The H11F3M photo-FET has an isolation voltage of 7.5kV, so it is safe to control high-voltage circuit parameters. However, the non-linear transmission characteristics of these devices can be a problem (Figure 1). To correct for this non-linearity, a simple feedback mechanism can be used to create a linear response to the potentiometer (Figure 2). The circuit uses two phototransistors, one for feedback and the other for the required Isolation potentiometer applications. The two photoelectric FET input in series, you can ensure that the input LED has the same amount of current. FET output put 50kΩ resistor to simulate the potentiometer response. The circuit amplifies the difference between the set input voltage (adjusted with potentiometer R7) and the feedback from photodiode FET1. The resulting output controls the current in the photo FETLED until the feedback voltage equals the input voltage. The output voltage follows the input voltage linearly (Figure 3). Maybe you will think of the same part number for optoelectronics