|Wiring Arrangement Between Components in the PCB|
PCB layout is the basic course for every electronic engineer, but often everyone only pays attention to wiring, and ignores the wiring arrangement between the components in the PCB.
●There is no cross-circuit in the printed circuit. For the lines that may cross, you can use the drill and “around” to solve the problem. That is, let a lead pass through the gap under other resistors, capacitors, and triodes, or One end of a lead that may cross is wound around. In a special case, the circuit is complicated. To simplify the design, it is also possible to bridge the wire and solve the cross circuit problem.
●Resistors, diodes, tubular capacitors and other components have vertical ", horizontal two installation methods. Vertical refers to the assembly body is perpendicular to the circuit board installation, welding, its advantage is to save space, horizontal refers to the assembly body Parallel and close to the board for mounting and soldering, the advantage is that the mechanical strength of the component mounting is better. The spacing of the components on the two different mounting components is different.
●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. The circuit with such a grounding method works stably. Not easy to excite.
●The total ground wire must be strictly in accordance with the high-frequency - intermediate frequency - low-frequency first-class order according to the order of weak electricity to strong electricity, must not be turned over and over again, the level and the stage prefer to connect long, but also Keep this rule. In particular, the grounding line arrangement requirements of the frequency conversion head, the regenerative head, and the frequency adjustment head are more strict, 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.
●The trace with high impedance should be as short as possible, and the trace with low impedance can be longer, because the trace with high impedance is easy to emit 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 reduces the separation.
●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.