Wiring arrangement and rational layout of devices on PCB

Cross-circuits are not allowed in printed circuits. For possible intersecting lines, it can be solved by "drilling" or "winding". That is, let a certain lead be "drilled" from the gap under other resistors, capacitors, and triodes, or "wrap" from one end of a lead that may cross. How to make the circuit complicated in special cases, to simplify the design It is allowed to bridge the wires to solve the cross circuit problem.

Arrangement and reasonable layout:

(1) Cross circuit is not allowed in the printed circuit. For the lines that may cross, it can be solved by “drilling” or “winding”. That is, let a certain lead be "drilled" from the gap under other resistors, capacitors, and triodes, or "wrap" from one end of a lead that may cross. How to make the circuit complicated in special cases, to simplify the design It is allowed to bridge the wires to solve the cross circuit problem.

(2) Components such as resistors, diodes, and tubular capacitors are available in both "vertical" and "horizontal" versions. Vertical refers to the assembly and soldering of the component body perpendicular to the circuit board. The advantage is that it saves space. The horizontal type refers to the parallelism of the component body and the installation and soldering of the circuit board. The advantage is that the mechanical strength of the component installation 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 cause interference and self-excitation, and the circuit of "one-point grounding method" is used. Stable, not easy to self-excited.

(4) The total ground line must be strictly in accordance with the order of high frequency-intermediate frequency-low frequency first level according to the order of weak current to strong power. It must not be turned over and over again. It is better to connect the stage and the stage. 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 they are improper, they 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, such as the two-way ground connection, it is easy to produce crosstalk, so that the separation is reduced.