1, selected integrated circuits, transformers, transistors and other components that are bulky, there are many pins and play a major role in the circuit, and then extracted from the selected reference pin in order to reduce errors.
2, if the PCB is marked with element numbers (e.g. VD870, R330, C466, etc.), because the serial numbers of a specific rule, the same elements Arabic letters behind the functional unit is the same, thus drawing it should be used. Correctly distinguish the same functional unit of the drawing is the basis of the layout of the components.
3, if the sequence number of the component unlabeled printed circuit board, it is preferable to their number, to facilitate analysis and calibration. In the design of printed circuit board components, manufacturers often members of the same functional units are arranged opposite, in order to minimize the wiring copper foil. Once the device has found the core functions, as long as it can find to find the other components of the same functional units.
4, to correctly distinguish the ground line of the printed circuit board, the power supply lines and signal lines. In the power supply circuit, for example, a negative electrode connected to the secondary of the transformer rectifier power supply is a positive power supply, typically a large capacity filter capacitor connected between the ground and the ground, a capacitor having a polarity marker housing. Power and ground pins may be found from the three-terminal regulator. When the factory on the printed circuit board wiring, and to prevent self-interference, generally a copper foil ground widest set (usually the high frequency circuit has a large area ground copper), a copper foil is the second power source, using the signal of copper . Foil is narrowest. Further, in the analog and digital electronic circuits, the printed circuit board is usually distinguish it from the ground, forming a separate ground grid, can also be used to identify and determine the base.
5, in order to avoid excessive wiring element, a wiring circuit diagram of a cross-interleaved, resulting in image confusion, and can be used for a large number of power and ground terminals and a ground marking symbols. If there are many components, you can draw a separate unit and then combined circuit.
6, when the sketch is recommended to use a transparent tracing paper, color and multi-color pen to draw the ground, power lines, signal lines, and other elements. When changes gradually deepen the color, visually conspicuous with the drawing, in order to analyze the circuit.
7, the master unit circuit of some basic components and classical drawing method, such as a bridge rectifier, voltage regulator and an operational amplifier circuit, a digital integrated circuit. The circuit unit is directly drawn into the frame of the circuit diagram, drawing efficiency can be improved.
8, when drawing the circuit diagram, you should find similar products as circuit diagram for reference, so you can use fewer resources to do more things.
Finally pcb share some relevant information to facilitate learning reference
PADS-PCB artwork rendering
http://www.makeru.com.cn/live/4006_1430.html?s=45051
Old driver purse -PCB Daniel practicing Cheats
http://www.makeru.com.cn/live/3472_1296.html?s=45051