1. Select components such as integrated circuits, transformers, transistors, etc., which are bulky, have many pins and play a major role in the circuit, and then extract from the selected reference pins to reduce errors.
2. If the PCB is marked with component numbers (such as VD870, R330, C466, etc.), since these serial numbers have specific rules, components with the same Arabic numerals after English letters are the same functional unit, so the drawings should be used. Correctly distinguishing components of the same functional unit is the basis of drawing layout.
3. If the serial number of the component is not marked on the printed circuit board, it is best to number it yourself to facilitate analysis and proofreading. When designing printed circuit board components, manufacturers often arrange components of the same functional unit opposite each other in order to minimize copper foil routing. Once you find a device with core functionality, simply find it to find other components of the same functional unit.
4. Correctly distinguish the ground wire, power wire and signal wire of the printed circuit board. Taking the power circuit as an example, the negative pole of the rectifier connected to the secondary of the power transformer is the positive pole of the power supply. Large-capacity filter capacitors are generally connected between ground and ground, and the capacitor casing has polarity markings. The power and ground wires can also be found from the three terminal regulator pins. When the factory wires the printed circuit board, in order to prevent self-excitation and anti-interference, the ground copper foil is generally set to the widest (high-frequency circuits usually have a large area of ground copper foil), the power copper foil is the second, and signal copper is used . The foil is the narrowest. In addition, in electronic products with analog and digital circuits, the printed circuit board usually separates its ground wires to form an independent ground grid, which can also be used as the basis for identification and judgment.
5. In order to avoid excessive wiring of components, the wiring of the circuit diagram is crisscrossed and staggered, resulting in confusing images, and a large number of terminal markings and grounding symbols are used for power and ground wires. If there are many components, the unit circuits can be drawn individually and then combined.
6. When drawing sketches, it is recommended to use transparent tracing paper and use multi-color pens to draw ground wires, power wires, signal wires, components, etc. in color. As you revise, gradually darken the colors to make the drawing visually compelling for analyzing the circuit.
7. Be proficient in the basic composition and classic drawing methods of some unit circuits, such as rectifier bridges, voltage stabilizing circuits and operational amplifiers, and digital integrated circuits. These unit circuits are directly drawn into the framework of the circuit diagram, which can improve drawing efficiency.
8. When drawing a circuit diagram, you should try your best to find circuit diagrams of similar products for reference, so that you can do more with less resources.