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    What are the typical products of the 13.56 MHz RFID tag?

    IS0 14443 Type A card, IS0 14443 Type B card, IS0 15693 (electronic label) card, CODE (electronic label) card, SONY Felica card, Chinese second-generation ID card.

    What are the circuit characteristics and circuit analysis methods?

    • The negative polarity full-wave rectifier circuit is the same as the positive polarity full-wave rectifier circuit. Two rectifier diodes are used to form a set of rectifier circuits, and the AC voltage input circuit is the same. The difference is that the negative poles of the two rectifier diodes are connected to both ends of the secondary winding of the power transformer instead of the positive poles.
    • The working principle analysis method of the negative polarity full-wave rectifier circuit is the same as that of the positive polarity full-wave rectifier circuit. It’s just that when the rectifier diode is turned on, the current flows through the load circuit from bottom to top, which is a bit difficult to understand.

    Compared with PLC band-pass couplers, transformer coupling circuits are widely used in low-voltage PLCs. Why?

    Mainly because:
    ①The transformer current can isolate the power line network;
    ②When the high voltage transient is saturated, the transformer can be used as a limiter.

    Briefly describe the origin of PLC?

    In 1969, Digital Equipment Corporation (DEC) in the United States developed the first programmable controller.
    In 1971, Japan, Germany, the United Kingdom, and France successively developed programmable controllers adapted to their own countries.
    In 1974, my country also began to develop and produce programmable controllers. Early programmable controllers were designed to replace relay control systems. It is used for switch quantity control and logical operation. Therefore, it is called Programmable Logic Controller (Programmable Logical Controller, PLC for short).
    In the late 1970s, the programmable logic controller developed from the switch quantity control to the computer digital control field, and had more functions of the computer. Therefore, the International Electrotechnical Commission (IEC) calls the programmable logic controller a programmable controller (Programmable Controller, PC for short). Later, in order to distinguish it from personal computer (Personal Computer, PC), people use PLC as the abbreviation of programmable controller.

    According to the measurement of the displacement object, the inductive synchronizer can be divided into why?

    According to the different objects to be measured, inductive synchronizers can be divided into linear inductive synchronizers and circular inductive synchronizers. The former is used to measure the linear displacement, and the latter is used to measure the rotation angle.

    What are the outside of the system?

    1. DMA Controller
    2. Vectored Interrupt Controller
    3. TrustZone Protection Controller
    4. Timer with PWM (Pulse Width Modulation)Timer with PWM (Pulse Width Modulation)
    5. 16-bit Watchdog Timer
    6. RTC (Real Time Clock)

    What does the artificial intelligence method include?

    Artificial intelligence methods include logical reasoning methods such as probabilistic reasoning, evidence reasoning, fuzzy reasoning and generating rules.

    What is the development trend of Rongchi Network?

    A future development trend of the latent network is as a heterogeneous overlay network. Covers various networks and regions such as the Internet, and can better maintain compatibility.
    With the continuous development of late-tolerant network science theory, it will certainly provide technical support for information exchange in more application fields. This will greatly promote the development of intelligent, ubiquitous, and integrated latency-tolerant networks.
    In view of the contradiction between low spectrum utilization and increasing spectrum demand in future network applications. In the future, it is an inevitable development trend to adopt the cognitive radio technology of dynamic spectrum access in delay-tolerant network applications.
    This requires the organic combination of cognitive radio and delay-tolerant network, and further research on the network layer of cognitive radio aided DTN (cognitive radio aided DTN). A cross-layer DTN routing protocol that combines spectrum sensing and routing is implemented, thereby improving spectrum utilization.

    What are the main technical requirements for the substation?

    Load Forecasting.
    Auxiliary vibration detection.
    Substation equipment status maintenance.
    Equipment information and operation and maintenance strategies are fully shared and interacted with power dispatching.
    Unified collection of network-wide operation data and synchronization and sharing of related data. Support the safe and stable operation of power grids at all levels and various advanced monitoring applications.
    network security mechanism.

    What are the detection methods for Resistorss and potentiometers?

    1. Appearance inspection For fixed resistors, first check that the signs are clear, the protective paint is intact, no scorch, no scars, no cracks, no corrosion, and the resistor body is in close contact with the pins. For the potentiometer, it should also be checked that the shaft is flexible, the tightness is appropriate, and the hand feels comfortable. If there is a switch, check whether the switch action is normal.
    2. Multimeter detection:
      • The detection of fixed resistance is to measure the resistance with the electric barrier of the multimeter, and choose different multipliers of the multimeter for the resistance of different resistance values. For an analog multimeter, the reading due to electrical resistance is non-linear. The larger the resistance value, the denser the indication. Therefore, to choose a suitable range, the deflection angle of the needle should be larger. Indicated at 1/3 ~ 2/3 full scale, the reading is more accurate. If the measured resistance value exceeds the error range of the resistor, the resistance value is infinite, the resistance value is 0 or the resistance value is unstable, it means that the resistor is broken. Be careful not to touch the two pins of the resistor with the hand holding the resistor during the measurement. In this way, the resistance presented by the hand will be connected in parallel with the measured resistance, which will affect the accuracy of the measurement. In addition, use a multimeter to electrically block the resistance value of the resistor in the detection circuit when it cannot be charged. In-line detection should first be powered off, then the resistors should be disconnected from the circuit, and then measured.
      • The detection of fuse resistance and sensitive resistance fuse resistance is generally only a few to tens of ohms. If the measured resistance value is infinite, it has been blown. The resistance of the fuse can also be detected online, and the voltage to the ground at both ends of the fuse can be measured separately. If one end is the power supply voltage and the other end is 0 volts, the fuse resistor has blown. There are many types of sensitive resistors. Taking the thermistor as an example, it is divided into positive temperature coefficient and negative temperature coefficient thermistors. For positive temperature system (PTC) thermistors, the resistance is generally not large at room temperature. In the measurement, a hot electric soldering iron is used to approach the resistance, and the resistance value should increase significantly at this time, indicating that the resistance is normal. If there is no change, the component is damaged, and the negative temperature thermistor is the opposite. The resistance value of the photoresistor measured by the multimeter is large in the absence of light (hand or object to block the light), and the resistance value indicated by the light meter needle is significantly reduced. If there is no change, the component is damaged.
      • Detection of variable resistance and potentiometer First measure whether the resistance value between the two fixed ends is normal. If it is infinite or zero ohms, or it is too different from the nominal value and exceeds the allowable error range, it means that it is damaged. The resistance of the resistor body is normal, and then connect a test lead of the multimeter to the sliding end of the potentiometer. The other test lead is connected to any fixed end of the potentiometer (adjustable resistance), slowly rotate the shaft handle, and observe whether the needle changes smoothly. When rotated from one end to the other, the resistance changes from zero ohms to the nominal value (or vice versa). And if there is no jump or jitter, it means that the potentiometer is normal. If there are jumps or jitters during the rotation, it means that the sliding point is in poor contact with the resistor body.
    3. Measuring the resistance with a bridge If it is required to accurately measure the resistance value of the resistor, it can be tested by a bridge (digital). Insert the resistor into the measuring end of the bridge element, select the appropriate range, and then read the resistance value of the resistor from the display. For example, when a resistance wire is used to make a resistor or a fixed resistor is processed to obtain a more accurate resistance value. It is necessary to measure the resistance of the self-made resistor with a bridge.


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