在电子线路调试时,经常需要用示波器来观察信号波形。常见的双踪示波器只能同时显示两个信号,往往难以满足同时观察多路信号的需要。笔者在两路输入的电子开关基础上作了改进,将两路扩充至四路。四路输入电子开关电路主要由信号输入、放大调零、开关电路、开关控制电路和电源五部分组成,电路原理图如图1所示。 (一)信号输入部分信号由输入端A、B、C、D四路输入,经过电位器分压后,送到由T_1～T_4组成的四个射极跟随器。调节电位器可改变输入信号的大小。信号输入电路采用射 In the electronic circuit debugging, often need to use oscilloscope to observe the signal waveform. Common dual trace oscilloscope can only display two signals at the same time, it is often difficult to meet the needs of simultaneous observation of multiple signals. The author made improvements on the basis of two-way input electronic switch, and expanded the two-way to four-way. Four input electronic switch circuit mainly by the signal input, zoom zero, switch circuit, switch control circuit and power supply five parts, the circuit diagram shown in Figure 1. (A) signal input part of the signal from the input A, B, C, D four input, after potentiometer partial pressure, sent to the T_1 ~ T_4 composed of four emitter follower. Adjust the potentiometer to change the size of the input signal. Signal input circuit using radio