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本电路通过一个微音器M,将接收到的外界声音转换成音频电流,经三个PNP型晶体管放大,用耳机收听,从而起到助听的作用。本电路(见图1)所用元件比较少,对规格无特殊要求。它只用一节5号电池,一般可使用半年以上。本机具有体积小、耗电少、灵敏度高、装置调试方便的优点。BG1_(1-3)均为3AX型晶体管(最好选噪声低的),电阻器用1/4W的,C_1、C_2均为5μF耐压3V的电解电容。
The circuit through a microphone M, the received external sound into audio current, amplified by the three PNP transistor, with the headset to listen to play a hearing aid. The circuit (see Figure 1) uses fewer components, no special requirements on the specifications. It only uses a 5th battery, generally can be used more than six months. The machine has the advantages of small size, low power consumption, high sensitivity and convenient device debugging. BG1_ (1-3) are 3AX type transistors (the best choice for low noise), resistors 1 / 4W, C_1, C_2 are 5μF voltage 3V electrolytic capacitors.