Have you ever made these mistakes in in circuit design?

P1: it doesn't matter to choose any resistance of high/low resistance.I would like to use the integer number：5.

Analysis:The market does not exist 5K resistance, the closest is 4.99K (accuracy of 1%), followed by the 5.1K (5% accuracy. The cost is separately 4 and 2 times higher than the 4.7K.

P2: What color should be used for the indicator on the panel? I think the blue is pretty special.

Analysis: Red, green, orange and other colors, regardless of its size (5MM below) and packaging, those colors have been used for decades, the price is generally less than 5 cents, while the blue is just invented nearly three or four years.The technical maturity and supply stability are poor.As a result,the price has to expensive four or five times than others.

P3: Using the 74XX as basic logic gates would be okay, but it seems that the CPLD is more elegant.

Analysis: The 74XX gate circuit only costs a few cents, while the CPLD at least costs a few dollar, (Although GAL / PAL also costs less, but it is not recommended). In addition to the high cost of CPLD, it also brings more multifarious works in production and documentation.

P4: To adapt our professional and advanced system, we should choose the fastest chips, including in MEM, CPU, FPGA and all needed chips.

Analysis: In a high-speed system, it doesn't means every part of the system all under the high-speed state. The speed level higher, the price of chips costs more.Unless the price, it would bring a significant negative impact to signal integrity.

P5: As long as the program can steadily operate, it is no matter how long is the code.

Analysis: it is a high ratio of performance, if you spend more time to modify the code which can greatly improve the efficiency of the program.That means you don't need to cost more to buy a high-performance CPU and memory.This also can be applied in CPLD / FPGA design.

 Author ：Darcy Beaufort — WIN SOURCE ELECTRONICS