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一、音响和告警电路 1.电子门铃和电码练习器 图1是一个最简单的音频信号发生器。其振荡频率可按下式计算:f=1.433/(R1+2R2+2RP)C1 调整电位器RP,可使振荡频率在300赫-10千赫范围内变化。故可用它作为调测收音机的音频信号源。 在输出端接一个扬声器BL,若将开关SA换成按钮开关,则成为一个电子门铃。按一下按钮开关,电路振荡,扬声器BL发声。 如果把按钮开关换成击打式电键,将振荡频率调整在800赫左右,则成为一个莫尔斯电码练习器。
First, audio and alarm circuit 1. Electronic doorbell and code practice Figure 1 is one of the most simple audio signal generator. The oscillation frequency can be calculated by the following formula: f = 1.433 / (R1 + 2R2 + 2RP) C1 Adjust the potentiometer RP, the oscillation frequency in the range of 300 Hz -10 kHz range. So it can be used as the audio signal source tuning radio. A speaker BL is connected to the output. If the switch SA is replaced by a pushbutton switch, it becomes an electronic doorbell. Press the button switch, the circuit oscillation, the speaker BL sound. If the button switch to hit the keys, the oscillation frequency is adjusted at about 800 Hz, then become a Morse code trainer.