"Strange trick" amplifier

J.M317 is regarded as a voltage follower with high input impedance and low output impedance
. There is a stable potential difference of 1.25V between its adjusting pin and the output pin. As long as the audio signal is input to its adjusting pin, the output will be The pin can get the same audio voltage with low output impedance
, which acts as a current amplifier.
    The circuit is shown in Figure 6-26. 9 0 1 4 acts as a voltage amplification stage. Because the input impedance of 317 is high, its operating current
only needs 0.6mA. R 1 and C 3 are power decoupling, C4 prevents circuit oscillation, and R3.R4 divides the voltage to provide bias and AC and DC
feedback to VT to improve linearity and DC stability} R5 has high power consumption and must use low cement resistors can be competent; it is barely possible to replace it with electric stove wire, but its thermal stability is slightly worse. The power transformer must have 50w power to have a two-channel shared port.