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在中高档收录机中,能见到一个或一串红色的发光二极管作音频电平指示,随着声音大小的变化闪闪发光,颇逗人喜爱。这里给您介绍一个结构简单、不要调试的发光二极管音频电平指示电路。全部元件都安装在一块22×10mm的印刷线路板上,很容易装进一般收录机或便携式收音机之中。线路及原理(见图1):b、c两端接上电源,a点接到喇叭非地端子上。当收音机的输出电压高于0.5V时,BG1开始导通,发光二极管中有电流流过而开始发光;输出电压升高到0.7V时,BG1饱和,发光二极管中电流最大,发光最强。
In the high-end tape recorders, you can see a red or a string of light-emitting diodes for audio level indication, with the sound changes in the size of the sparkling, quite cute. Here to introduce you to a simple structure, do not debug the light-emitting diode audio level indicator circuit. All components are mounted on a 22 × 10mm printed circuit board, it is easy to put into the general radio or portable radio. Line and principle (see Figure 1): b, c both ends connected to the power supply, a point received speakers on the ground terminal. When the output voltage of the radio is higher than 0.5V, BG1 starts to conduct, current flows in the LED to start emitting light. When the output voltage rises to 0.7V, BG1 is saturated, and the current in the LED is the maximum and the light is the strongest.