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  1. I read an electronic magazine in which there is a report on moisture sensors can be used in soils. After reading, I became interested in the uses of moisture sensors in soils. So I searched some related materials and information from google about this topic. Today I come to this forum to turn to you to discuss my understandings are appropriate. Here are my personal understandings: Soil water is the main source of water absorption (except for hydroponic plants), the state and change of soil moisture content, which is the main determinant of plant growth status, which affects human food safety and ecological environment. Thus, the soil and water on Earth are the basis of human and even life, through the soil moisture sensor to measure the water content of the soil, the current well-known mainly for the following purposes: To provide decisive support for scientific irrigation At present, agricultural water consumption accounts for 92% of the world's fresh water consumption. In China, the national average utilization rate of agricultural irrigation water is only 45% (see Baidu Encyclopedia "irrigation water use coefficient"), 55% of the water after extensive irrigation, a large number of leakage into the plant roots below the surface runoff loss, water Channel leakage and other ways to be wasted. In 45% of the water is preserved in the soil, and because of blind irrigation, non-on-demand irrigation, water and fertilizer integration is not in place and other reasons, a lot of water can not be effectively used crops. The use of soil moisture sensor can dynamically track the depth of the crop root in the soil in the specific depth of the crop roots of the dynamic absorption of water consumption; the use of soil moisture sensor recorded soil moisture curve, can be intuitive and quantified way to show The water content of different soil layers in soils changed with time, and then the key factors such as irrigation depth, irrigation amount, irrigation start time, irrigation duration, irrigation limit and soil moisture content were obtained. Scientific irrigation decisions make it useful for the crop to live in a soil where the crop is truly comfortable and to increase crop yields. On the other hand, people do not always want to control the survival of crops in a comfortable environment to increase production, people will consider the quality of agricultural products. For example, the appropriate soil moisture will make the grape yield is high, but the grapes will not necessarily sweet. In the late stages of grape growing, the use of soil moisture sensors is to monitor the soil moisture content, so that the soil moisture content to maintain a relatively low state of the state, in the United States, Spain, the United States and other high-quality wine-producing areas. For the government departments to provide data support, policy basis The soil moisture and soil temperature data monitored by the soil moisture sensor are the relevant government activities, such as agriculture, water conservancy, meteorology and land, and formulate and implement relevant policies. It is also one of the basic public services provided by the government for the people. For example, in recent years, the local governments have been actively launched by the government-funded agricultural information service platform for the local people to provide a lot of soil moisture data, spring water harvesting guide, soil moisture sensor is one of the basic sources of these data. In the national drought and flood control system, there are a large number of installed in the country's drought, moisture monitoring stations, hydrological stations, soil moisture sensors are the most important and most basic instruments of these sites. Provide early warning for natural disasters such as landslides In 2013, there were 15403 geological disasters in China, of which 9849 were landslides, resulting in incalculable personal injury and property damage. A large number of landslides are caused by rainfall and other factors to increase the water content of the mountain, hillside weight increases, the slope of gravity than the lower soil see the friction and then landslides. Soil moisture sensor is the most important and basic instrument of mountain landslide monitoring and early warning system. For the soil, plants, the environment and other scientific research data Soil moisture sensors are widely used in soil science, plant growth in water relations research, landfill leaking monitoring, fertilizer utilization optimization, global warming impact research and other fields. Ps: Excuse me if I was wrong in words or expressions as I am a green hand in the field of moisture sensors. I need continual learnings. What is your idea ? Do you agree with my ideas ? Any of your ideas would be highly appreciated. May someone would like to help ? thanks in advance
  2. I read an electronic magazine in which there is a report on what are the reed relays used. After reading, I became interested in reed relays. So I searched some related materials and information about this topic. Today I come to this forum to turn to you to discuss my understandings are appropriate. Here are my personal understandings: The contact form of the reed relay depends on the reed switch used. Reed switch has normally open (H), normally closed (D) and conversion (Z) three forms. The reed reed of the normally open reed is fixed at both ends of the glass tube, and the magnetic properties at one end are opposite to the other end under the action of the coil (magnet), so the two contacts rely on the magnetic "To close the shrapnel elasticity and closed; normally closed reed rod reed is fixed on the same end of the glass tube, under the action of the external magnetic field produced by the same magnetic, so the two contacts rely on" homosexual repulsion " To overcome the elasticity of the reed and broken; in the normally closed reed on the basis of reed with a normally open reed, it constitutes a conversion type of contact. Reusable sensor quality and reliability The most notable application is for automatic test equipment (ATE). In this equipment technology is first-class, reed switch is used for reed relays, it is used in IC, ASIC, silicon test equipment and printing test equipment, as a switch. In these applications, a test system in the reed switch can reach 20,000. The failure rate of a relay is set at 50ppm, so to meet this requirement, the quality of the reed relay is much better than the 50ppm requirement. So far, has not heard of a mechanical and electrical devices have such a level of quality. Similarly, it also applies to some semiconductor devices. Once the quality test of the initial work is done, the reed relay needs to perform well within its lifespan. At this point they have proven to be better than all other switching devices. This is because in many cases, ATE work 24 hours a day, 7 days a week, it is the cost of the most important. So the working life of the reed relay needs millions of times. Another example of a reed relay is that it is used as a balloon sensor in which it passes time tests in harsh security applications. Reed switch is widely used in many demanding automotive safety equipment (such as the height of sensitive brake fluid), in many medical equipment applications, including cautery equipment, pacemakers and other medical electronic equipment. On these devices, the reed relay relieves a small leakage current. Reed relays are electromagnetic interrupters with sealed contacts. Reed relays can reflect the voltage, current, power and current polarity and other signals, in the detection, automatic control, computer control technology and other fields widely used. Reed relays are mainly composed of dry reed and reed coils. Reed relays have: simple structure, small size. Contact life, generally up to 10 of the 7 side or so. Reed relays can also be used to drive permanent magnets, reflecting non-electrical signals, for limit and stroke control and non-power detection. The main components for the reed relay reed water level signal for industrial and civil buildings in the water tank, water towers and pools and other open containers of water level control and water level alarm. Electromagnetic relay is the use of electromagnets to control the working circuit off the switch. (1) Structure: The main components of the electromagnetic relay are electromagnet A, armature B, spring C and movable contact D, static contact E. (as shown) (2) The working circuit can be divided into two parts: low voltage control circuit and high voltage working circuit. The low voltage control circuit includes electromagnetic relay coil (electromagnet A), low voltage power supply E1, switch S; high voltage working circuit includes high voltage power supply E2, motor M, Relay contacts D, E parts. (3) working principle - closed low-voltage control circuit switch S, the current through the solenoid A coil to produce a magnetic field, so that the armature B gravity, the dynamic and static contact D and E contact, the working circuit is closed, the motor work ; When the low-voltage switch S is disconnected, the current in the coil disappears, and the armature B, under the action of the spring C, disengages the movable and static contacts D, E, the working circuit is disconnected and the motor stops working. As long as the coil at both ends with a certain voltage, the coil will flow through a certain current, resulting in electromagnetic effects, the armature will be attracted by the role of electromagnetic force to overcome the return of the spring to pull the iron core, Moves the contact with the static contact (normally open contact). When the coil is powered off, the electromagnetic force will disappear, the armature will return to the original position of the spring, so that the movable contact with the original static contact (normally closed contact) release. So that pull, release, so as to achieve the circuit in the conduction, cut off the purpose. For the relay "normally open, normally closed" contacts, it can be distinguished: relay coil is not in power when the state of the static contact, known as the "normally open contact"; in the state of the static contact As "normally closed contact". Electromagnetic relay is an important part of the bell, telephone and automatic control circuit device. Its essence is the switch controlled by the electromagnet, which plays a similar role in the circuit: (1) control the high voltage with low voltage and weak current, High current; (2) to achieve long-range operation and automatic control. Electromagnetic relays are widely used in automatic control (eg, refrigerators, cars, elevators, machine tools, etc.), which can be used to control high voltage and high current working circuits with low voltage and weak current control circuits, and can realize remote control and production automation In the control circuit) and the field of communication. Ps: Excuse me if I was wrong in words or expressions as I am a green hand in the field of reed relays. I need continual learnings. For more information, please feel free to visit the site at the following link: http://www.kynix.com/Parts/3882497/W117SIP-6.html. What is your idea ? Do you agree with my ideas ? Any of your ideas would be highly appreciated. May someone would like to help ? thanks in advance
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