First, consider the size of the pcb. If the pcb size is too large, the printed line will be long, the impedance will increase, the anti-noise ability will decrease, and the cost will also increase; After sizing the printed circuit board, determine the location of special components. Finally, all components of the circuit are laid out according to the functional units of the circuit.

      When locating special components, follow these guidelines:

1. Minimize the connection between high-frequency components and minimize their distribution parameters and mutual electromagnetic interference. Components susceptible to interference should not be placed too close together, and input and output components should be kept as far apart as possible.

2. There may be a high potential difference between some components or wires, and the distance between them should be increased to avoid accidental short circuit caused by discharge. Components with high voltage should be arranged in places that are not easily accessible by hand during debugging.

3. Parts weighing more than 15g should be fixed with brackets and then welded. Those components with large volume, heavy weight and high heat generation should not be installed on the printed circuit board, but should be installed on the chassis bottom plate of the whole machine, and the heat dissipation problem should be considered. Thermal elements should be kept away from heating elements.

4. The arrangement of potentiometers, adjustable inductance coils, variable capacitors, micro switches and other adjustable components should consider the structural requirements of the whole machine. If it is adjusted inside the machine, it should be placed on the printed board where it is convenient to adjust; if it is adjusted outside the machine, its position should be compatible with the position of the adjustment knob on the chassis panel.

5. The position occupied by the positioning hole of the printed board and the fixing bracket should be reserved.