Arrangement of wiring between printed circuit board components
(1) Cross circuits are not allowed in printed circuits. For lines that may cross, two methods of “drilling” and “winding” can be used to solve them. That is, let a lead “drill” through the gap at the foot of other resistors, capacitors and triodes, or “wind” through one end of a lead that may cross. Under special circumstances, the circuit is very complex. In order to simplify the design, it is also allowed to use a wire jumper to solve the problem of cross circuit.
(2) Resistors, diodes, tubular capacitors and other components can be installed in “vertical” and “horizontal” modes. Vertical refers to the installation and welding of the component body perpendicular to the circuit board, which has the advantage of saving space. Horizontal refers to the installation and welding of the component body parallel and close to the circuit board, which has the advantage of good mechanical strength. For these two different mounting components, the component hole spacing on the printed circuit board is different.
(3) The grounding point of the same level circuit shall be as close as possible, and the power filter capacitor of the current level circuit shall also be connected to the grounding point of this level. In particular, the grounding points of the base and emitter of the transistor at the same level cannot be too far away, otherwise the interference and self excitation will be caused due to the too long copper foil between the two grounding points. The circuit with such “one point grounding method” works stably and is not easy to self excitation.
(4) The main ground wire must be arranged in strict accordance with the principle of high frequency, medium frequency and low frequency in the order of weak current to strong current. It is not allowed to turn over and over randomly. It is better to have a long connection between stages, but also abide by this provision. In particular, the grounding wire arrangement requirements of frequency conversion head, regeneration head and frequency modulation head are more strict. If it is improper, it will produce self excitation and fail to work.
High frequency circuits such as frequency modulation head often use large-area surrounding ground wire to ensure good shielding effect.
(5) Strong current leads (common ground wire, power amplifier power lead, etc.) shall be as wide as possible to reduce wiring resistance and voltage drop, and reduce self excitation caused by parasitic coupling.
(6) The routing with high impedance shall be as short as possible, and the routing with low impedance can be longer, because the routing with high impedance is easy to whistle and absorb signals, resulting in circuit instability. The power line, ground wire, base line without feedback element, emitter lead, etc. are all low impedance lines. The base line of emitter follower and the ground wire of two sound channels of tape recorder must be separated into one line until the end of the effect. If the two ground wires are connected, crosstalk is easy to occur, reducing the degree of separation.