Simple little amplifier

Simple little amp

 

    Here are a compact design , simple but good performance line three tube audio amplifier. The circuit , see photos. Maybe you can see some similar to this circuit in some pocket transistor radio .

 

    Principle Analysis:

 

    Circuit as shown , the input electrode ( 9014 ) is equal to the base voltage of the transistor output stage the two midpoint voltage , typically half the supply voltage , this voltage by the stabilization of the base of the output transistor to control the two diodes . 3.3 ohm resistor in series with the emitter of the output transistor in order to stabilize the bias . To reduce the environmental temperature, the different devices ( such as diodes , the output transistor ) circuit of the distinction between the parameters . When the bias current increases, the output transistor and the base -emitter voltage decreases to reduce bias . This circuit input impedance of 500 ohms , when using an 8 -ohm speaker in the voltage gain of 5 .

 

    When the circuit undistorted output power of 50mW , about the speaker about 2V voltage swing . Increase the output power of the power supply voltage can be increased , but this should be noted that the output transistors heat. When 9V supply voltage , the circuit consumes about 30mA. Note that both the output power tubes magnification should be close to the production . Other device parameters can refer to icons to choose from. This circuit is suitable for making into a headphone amplifier or other small power amplifier used . Because it is a very typical amplifier circuit, it is very suitable for beginners to learn than the principle of the amplifier circuit , making hands- reference circuit when .

此主题相关图片如下：简单的小功放.gif

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