Here we introduce a BTL power amplifier circuit without debugging, high fidelity, and low cost, and can choose the final power amplifier integrated circuit according to your own situation. Due to its strong versatility, it brings great convenience to audio enthusiasts.
The working principle of the device circuit is shown in Figure 1. Only one circuit diagram of one channel is given here, the other channel is exactly the same. The audio signal is input from the A terminal of the circuit and amplified by the operational amplifier IC1 (the amplification factor is determined by R1 and R2). One channel is amplified inversely by IC2, and its gain is 1. The other channel is amplified inversely by IC3 and IC4 twice. , The gain is still 1, the essence is that IC3 and IC4 together form a positive-phase amplifier with a gain of 1, so the two audio signals that are equal and opposite in phase are obtained at the B end of IC2 and the C end of IC4. These two inverting audio signals are added to the â‘ and â‘¤ pins of the dual audio power amplifier IC5 (TDA2009) through R9, C5 and R10, C6 respectively. These two input terminals are the in-phase input and the inverting input End, so after power amplification inside IC5, output from IC5's â‘© foot and â‘§ foot, respectively, to push the speaker BL.
The list of components selection and debugging components is shown in the table below.
|R2, 20, 21||resistance||10K||3||C12, 13||Polyester capacitor||0.1u||2|
|R3, R9, R12||resistance||220K||3||C14||Electrolytic capacitor||10u||1|
|R4ï¼R7, 10, 11, 13, 16||resistance||20K||8||C15||Ceramic capacitor||0.01u||1|
|R8, 14, 15||resistance||100Î©||3||C16||Electrolytic capacitor||100u||1|
|R17, 18||resistance||10Î©||2||DW||Zener diode||20V||1|
|C1, 3, 4, 5, 6||Electrolytic capacitor||1u||5||IC1||Four op amp IC||TL084||1|
|C2||Electrolytic capacitor||4.7u||1||IC2||Two-channel power amplifier IC||TDA2009||1|
|C7, 8||Ceramic capacitor||1000P||2||BL||speaker||4ï¼8Î©||1|
|C9, 10||Electrolytic capacitor||220u||2|
Due to the versatility of this circuit design, any dual power amplifier integrated circuit output by OTL or OCL can be connected to the B and C ends of the differential amplifier to form a BTL amplifier. If the reader is interested, you can also insert the RC attenuation tone control circuit, which will receive better results.
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