几乎所有早期的音频驱动信号强度指示器在小信号时都不能工作。当信号调整到所要求的工作电平时,指针又停在满刻度不动。而这里则按另一种方式工作。无信号时,调节1M的电位器,使表上指示到零电流,51k电阻保证在250μA时T1的集电极电压降至接近零点。实际上,由于音量表对小信号的高灵敏度,当大电流导入时,三极管逐渐饱和。这里使用的是一只普通的 Almost all of the early audio-driven signal strength indicators did not work with small signals. When the signal is adjusted to the required operating level, the pointer stops at full scale again. And here is another way to work. When there is no signal, adjust the 1M potentiometer so that the meter indicates zero current and the 51k resistor ensures that the collector voltage of T1 drops to near zero at 250μA. In fact, due to the high sensitivity of the volume meter to small signals, the transistor gradually saturates when large currents are introduced. Here is a common use