This is Hifi transistor headphone amplifier circuit uses the principle enlarges current of the transistor at the beginning by use , 3 transistors. Which first perform be pre amp and next 2 again build model complementary which impedance of the circuit will that about 500 ohm and have amplifier rate 5 equal it give output power about 50 mW.
When entering power supply 9 volt, reach the circuit and feed input signal come in change C1 coupling signal go to reach bass pin (B) of Q1. By Q1 will enlarge a signal gives the power goes up in the one level for go to drive Q2 and Q3 work enlarge current get more and more. Which Q2 and Q3 will build the circuit model complementary. By have R5 and R6 build serial prevent stay for heal the stability of current be stable. From that time a signal output change C2 for lead go out be usable and the output signal. One part fed get back to change , R1 , come to reach input at bass pin (B) of Q1 for the circuit has good stability.
Some time a good ideas may not have one. The circuit below may be fond of you.
Transistor Headphone Amplifier circuit using BC109
Here is classic Headphone Amplifier because The important part of the circuit is Transistor BC109.
I like this circuit it very good for play music classic.
Low noise headphone amplifier circuit
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