(2) Components such as resistors, diodes, and tubular capacitors have two types of installations: “vertical” and “horizontal”. Vertical means that the component body is mounted perpendicular to the circuit board and soldered. The advantage is that it saves space. The horizontal type refers to the component body being parallel and close to the circuit board for mounting and soldering. The advantage is that the mechanical strength of component mounting is better. These two different mounting components have different component pitches on the printed circuit board.
(3) The grounding point of the same level circuit should be as close as possible, and the power supply filter capacitor of the current stage circuit should also be connected to the grounding point of the stage. In particular, the grounding point of the base and emitter of the transistor of this stage cannot be too far away. Otherwise, the copper foil between the two grounding points will be too long to cause interference and self-excitation. The circuit with such a "one-point grounding method" works better. Stable and not self-motivated.
(4) The total ground line must be strictly in accordance with the principle of high-frequency-intermediate-low-frequency first-order order according to the order of weak current to strong power. It must not be arbitrarily turned over and over again, and the stage and the stage are more likely to be connected long. To comply with this regulation. In particular, the grounding line arrangement requirements of the inverter head, the regenerative head, and the FM head are more stringent, and if it is improper, it will be self-excited and will not work.
High-frequency circuits such as FM heads often use large-area enclosed ground wires to ensure good shielding effect.
(5) The high current lead (common ground line, power amplifier power lead, etc.) should be as wide as possible to reduce the wiring resistance and its voltage drop, and reduce the self-excitation caused by parasitic coupling.
(6) Traces with high impedance should be as short as possible, and traces with low impedance can be longer, because traces with high impedance tend to flute and absorb signals, causing circuit instability. The power line, the ground line, the base trace of the non-feedback component, and the emitter lead are all low-impedance traces. The base trace of the emitter follower and the ground of the two channels of the recorder must be separated. Until the end of the function is combined, if the two ground lines are connected, it is easy to produce crosstalk, which makes the separation drop.
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