Circuit design not only has a lot of skills, but also a lot of misunderstandings. This article will introduce ten misunderstandings in the design of circuit stability. Myth 1: Product failure = product is not reliable There are problems with the product, sometimes it is not a problem of research and development. There have been cases, equipment for the developed areas in China and above, because it is used in China, so it is exported to Colombia, but there are frequent failures. The reason for the failure lies in the Chinese mainland. The elevations of the above developed areas are relatively low, so the airtightness of the equipment is challenged in high altitude areas, and the leak rate increases after the pressure difference between the inside and outside of the equipment increases. When the project was established, only low altitude was considered, so the design of the people was no problem. Your boss asked for it. Whoever decided to export this model to Colombia is the culprit. If the boss of the research and development is involved in the decision-making, Raising objections, he is simply the biggest sinner. After all, sales executives do not understand technology can be forgiven, and the vice president of technology is incompetent. Product reliability is the ability to perform specified functions under "specified time and specified conditions." The reader must carefully appreciate this definition, knowing what to know, and seeing who can achieve this definition can achieve more knowledge. The conditions used at the site often exceed the specified conditions, and this excess may be implicit. Myth 2: Transition process = steady state process The introduction of "A Curve Affecting Product Reliability and Social Harmony" is a good illustration of the content of this figure. (This knowledge is described in detail in the time domain analysis of the automatic control principle. Interested parties can view it by themselves) Myth 3: Derating is easy to do, no problem Anyone who derates, such as painting, who will, but not everyone can rely on painting to survive. For more details, please refer to the article "Derating Design for Electronic Products" in this blog. Here is a brief summary: 1. The derating factors of devices with the same function but different processes are different; 2. The derating factor of the adjustable device and the fixed value device are different; 3, the load is different, the derating factor is different; 4. The derating factor of the same specification wire is different when using multiple turns and single turn; 5. Some parameters cannot be derated; 6, the temperature drop can not be missed. Myth 4: Ta, the device can be used with confidence Why is device damage often referred to as "burning"? The reason is that the device failure is mostly thermal failure. There are two specific considerations. First, the ambient temperature of the device is the ambient temperature of the device. The device environment is affected by the heat dissipation of other devices in the chassis. The ambient temperature of the device is higher than the ambient temperature of the device. . Second, you can recall the third question at the beginning of this speech. For details, see "Common Errors in Device Environment Temperature and Load Characteristics." Myth 5: Electronic reliability has nothing to do with mechanical and software majors Installation, wiring, layout, and spraying process will affect electrical performance; electromagnetic compatibility, virtual soldering, heat dissipation, vibration and noise, corrosion, and grounding are all related to structure; software error prevention, error correction, error correction, and fault-tolerant treatment can avoid machinery And electronic defect issues. Myth 6: The device is very simple, there is no need for the Datasheet. When designing, be sure to get the datasheet of all the devices, then read all the graphical charts and parameters on it, and finally establish a connection with these curves. The following figure shows the VI characteristic curve of the diode. Care must be taken to confirm the static operating point of the device in our circuit. Myth 7: maintainability has nothing to do with me What is the purpose of electronic product reliability work? It is making money. What is the basis for making money? Open source and throttling, open source is difficult, and the flow is easy. Don't always think about saving material costs, saving materials, and high maintenance costs. From early death to late death, sooner or later, why bother? It is better to die early than to get pregnant. The best way is to pay attention to maintainability and save this part of the cost. This is a real profit. Myth 8: Poor process control is no good craftsman Process control is not only a problem for the craftsman, it is a value chain construction process. The design engineer's requirements for the device, the manufacturer's choice of the procurement engineer, and the control content of the inspection link shall be designed with respect to the key components of the device. The detection method shall not introduce the failure mechanism and damage of the component, and the assembly shall not introduce damage (peak). The temperature control of the welding furnace, the anti-static treatment of the hand-welded countertop, etc.), the factory inspection should check the part of the product parameter drift that may cause product failure, and the maintenance link should not introduce failure. It can be seen from the above that the problem arises which can be guaranteed by two process engineers in the district. Therefore, the specific approach is to establish consistency. The premise of consistency is that the designer provides sufficient and primary technical information. The process is only based on the design drawings and design documents to ensure that the manufacturing reliability is infinitely close to the design reliability. Misunderstanding 9: Relationship between MTBF value and failure rate of a single specific machine MTBF is a macroscopic and statistical concept. Single machine failure is a microscopic and specific concept. The customer likes to ask a question "The MTBF value of your product is 10,000 hours. Then, if I buy this one, is it not within 10000h?" This is a concept of Guan Gongqiu who is more powerful, let me Say the conversion relationship between them, you first tell me whether it is 1km or 1kg? Myth 10: Strengthening testing can solve reliability problems Since this problem can be listed as one of the top ten misunderstandings, its definition is naturally wrong. There are three conclusions: 1. Some problems cannot be detected by simulation test experiments; 2. Test method = engineering calculation + specification review + simulation test + electronic simulation; 3. The corresponding low temperature working time cannot be calculated by the results of the temperature strengthening test. We can supply all your mining equipment parts & heavy machinery mining parts. We provide parts & components for a wide range of mining equipement & heavy machinery including lifts, drills, loaders, roof bolters or any other mining equipment. Some of our mining and machinery parts include drive shafts, filters, axles, bushings, and hydraulic components. Cone Crusher,Mining Machinery Parts,Cone Crusher Adjustment Ring,Adjustment Ring For Crusher Shenyang Zhicheng Heavy Machinery Manufacturing Co., Ltd. , https://www.zhichengmachinery.com
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