Next step would be the quality assurance of the design. Tests for integration, environmental survival and qualification with respect to the product are performed. Finally, the customer agrees and signs the contract after he’s satisfied and his requirements are met.
Select Components Wisely
To elaborate on why the electronic components must be picked carefully for a product, the electrolytic capacitors would be a good example to consider. Power supplies contain lots of electrolytic capacitors. Unless the highly reliable electrolytic capacitors are used, the normal capacitors available in the market have a low shelf-life. Subramanyan points out, “For a 100 micro Farad capacitor, the capacitor contains a film inside formed at the time of manufacturing. The variations in tolerance for electrolytic capacitors range from -50 per cent to 100 per cent. So the capacitor could be 50 micro Farad or it could even be 200 micro Farad at the time of actual usage.”
For normal capacitors, he says, “The manufacturing tolerance is 10 per cent. If the product is made using these kind of electrolytic capacitors and has not been used for more thank one year and then subsequently used, the capacitor is no longer an electrolytic capacitor. It may be just a 2 or 3 micro farad capacitor but not 100 micro Farad.” So if the power supply is kept as a spare and has not been used for a long time, they would not work immediately when fed power. The same response is not achieved as desired similar to an ideal power supply.
These are the issues that the customer would not understand. According to the customer, the equipment has failed.
A Good Design is Equal to a Good Set of Requirements
A good set of requirements for a design has a number of characteristics. The most important characteristic is that the need or the purpose of the product must be met. In the case of the customer, it means whether it meets his requirements or specifications. If it covers all the requirements, it’s complete. It must also be unambiguous. There must be only one possible interpretation.
“If it’s ‘A’, there must be just an ‘A’, there cannot be a ‘B’,” notes Subramanyan.
Consistency is an important factor. There must be no conflicts between the requirements. It must also be verifiable, traceable and modifiable. “Especially considering today’s requirements in embedded design, people expect last minute changes in the program. For example, once the PCB is made, it’s obviously difficult to make changes in the basic circuit. Therefore, it must be easy to add new requirements,” says Subramanyan. He adds, “At the end of the day, it’s important to find out what the customer requires not what he wants.” This is one major issue that needs the most attention.
Analog vs Digital
Another area of consideration in the electronics design would be the analog vs. digital circuits. While designing the circuit, the amount of analog or digital that must be incorporated is not an easy task to decide. “It’s one area of trade-offs that electrical/electronic engineers consider while designing circuits,” believes Subramanyan.
Is it better to build an analog filter in the front end or would it be more appropriate to do digital signal processing to do the filtering?, Can an analog amplifier increase the signal magnitude sufficiently to reducing the amount of processing later?, Is reprogramming and reconfiguring the processing important enough to put functions in software and remove the analog circuits? – are the questions that need to be addressed and it’s important to put in a lot of thought into these questions. All of these trade-offs aim at reducing cost, unnecessary functions, development work and circuitry.
Quality is of paramount importance
As far as electronics is concerned, it should not be an after thought. Quality must be built-in right from the concept stage upto the final stage. The Parettos’ principal which says “Optimal of the sum is not equal to the sum of the optimals,” must be kept in mind while doing optimization. The design and development of new products requires the combination of electronic engineering knowledge with creativity, innovation skills and business know-how. Electronic Product Design is an ever-growing and a highly-demanding consumer driven market.
The author is a tech correspondent at EFY Bengaluru. This article is based on a talk, at Electronics Rocks 2012, by Mr. L R Subramanyan, Visiting Faculty at IIT-B, and Chairman of Seto Teknolog Pvt. Ltd.