(1) The printed circuit is not allowed to have a cross circuit, for the possible cross lines, you can use “drilling”, “winding” two ways to solve.
That is, let a lead from the gap at the foot of other resistors, capacitors, transistors “drill” in the past, or from the end of a lead may be crossed “around” in the past, in special cases how the circuit is very complex, in order to simplify the design also allows the use of wire crossover, to solve the problem of the cross circuit.
(2) resistors, diodes, tubular capacitors, and other components have “vertical”, “horizontal” two ways of installation.
Vertical refers to the assembly body perpendicular to the circuit board installation, welding, its advantage is to save space, horizontal refers to the assembly body parallel and close to the circuit board installation, welding, its advantage is that the mechanical strength of the assembly installation is better. For these two different mounting components, the hole spacing of the components on the printed circuit board is different.
(3) The connection point of the circuit of the same level should be as close as possible, and the power filter capacitor of the circuit of the level should also be connected to the connection point of the level.
In particular, the transistor base, emitter connection point can not be too far away, otherwise because the copper foil between the two connection point is too long will cause interference and self-excitation, the use of this “point grounding method” circuit, the work is more stable, not easy to self-excitation.
(4) the total ground wire must be strictly in accordance with the high frequency – medium frequency – low frequency level by level of weak to strong electric order principle, must not casually turn over and over to disorderly connection, level and level between would rather wiring long point, but also to comply with this provision.
In particular, the frequency conversion head, the regeneration head, the frequency modulation head grounding arrangement requirements are more strict, if it is improper will produce self-excitation so that it can not work.
In order to ensure a good shielding effect, a large area surrounding ground wire is often used in the frequency modulation circuits.
(5) strong current leads (common ground leads, power amplifier leads, etc.) should be as wide as possible, in order to reduce wiring resistance and its voltage drop can reduce the parasitic coupling generated by self-excitation.
(6) high impedance wiring as short as possible, low impedance wiring can be longer, because the high impedance wiring is easy to whistle and absorb signals, causing circuit instability. Power line, ground line, baseline of non-feedback component, emitter lead, etc., are all low impedance wiring. The baseline of the emitter follower and the ground line of the two sound channels of the recorder must be separated from each other in one way until they are reunited at the end of the function. If two ground lines are connected to each other, crosstalk is easily generated and the separation degree decreases.
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