The functional front stage adopts high-precision regulated power supply

It is a positive and negative symmetrical adjustable regulated power supply composed of positive and negative adjustable voltage regulators LM317 and LM337.
This power supply adds a level of pre-stabilization before voltage stabilization. Although the production cost of the power supply has increased, the output voltage The stability is not
comparable to that of general voltage stabilizing circuits. This power supply is suitable for the front-stage power supply of power amplifier circuits, and its effect is very ideal.
    In the circuit, the mains input first passes through the noise elimination filter composed of C1, Bi, c2, and island to
reduce the interference noise from the power supply to the minimum. Then it is stepped down by the transformer T2 and divided into two groups to supply power to the rectifier bridge. The rectified and filtered DC
voltage is first pre-stabilized by LM317 and LM337, and then finally
stabilized and output by the second pair of voltage regulators LM317 and LM337. Among them, RPi and RPz are the adjustment potentiometers for the positive and negative output voltages respectively. When RPi and RPz are adjusted
, the output voltage changes accordingly. The changes in the output voltage are fed back to the voltage adjustment terminals ADJ of the pre-stabilization stages
LM317 and LM337 through the feedback resistors R2 and Rs respectively, so that the pre-stabilization stage automatically adjusts accordingly, so that ultimately To
achieve the best voltage stabilizing effect
    , the inductor Ti adopts high-quality magnetic ring and is machine-operated. The wrapped wire of 0 is wound around the magnetic ring for 30 turns, a total of two groups. Then dip in insulating
paint and dry before use. The withstand voltage of Cl~C3 should be greater than 500v.