中文说明：
使用555时基电路产生频率为20kHz-50kHz的方波Ⅰ作为信号源；利用此方波Ⅰ，可在四个通道输出4种波形；每通道输出方波Ⅱ、三角波、正弦波Ⅰ、正弦波Ⅱ中的一种波形，每通道输出的负载电阻均为600欧姆。限用NE555、NE5532（或LM358）、电容和电阻若干。
English Description：
555 time base circuit is used to generate square wave I with frequency of 20KHZ-50KHZ as signal source; four kinds of waveforms can be output in four channels by using this square wave I; one of the waveforms of square wave II, triangle wave, sine wave I and sine wave II is output in each channel, and the load resistance of each channel is 600 ohm. It is limited to NE555, ne5532 (or lm358), capacitance and resistance.