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  • Ten Daily Electronic Common Sense-Section 103

    PLD is divided into several types of devices according to the programming process?

    • PLD can be divided into six categories from the programming process:
      1. Fuse type devices.
      2. Anti-fuse (Anti-Fuse) type device.
      3. EPROM type device.
      4. E2PROM type device.
      5. SRAM type device.
      6. Flash type device.

    What are the components of the sensor?

    It consists of three parts: sensitive element, conversion element and basic conversion circuit.

    In serial communication, what are the serial communication methods?

    1. Simplex system
    2. Half-duplex system
    3. Full-duplex system

    What are the main parameters of the inductor?

    (1) Inductance: ① Definition of inductance: Inductance is a physical quantity that measures the ability of an inductor to convert electrical energy into magnetic energy. When current flows through an inductor, a magnetic field is created. The greater the current, the stronger the magnetic field and the greater the magnetic flux Sha. The magnetic flux function is proportional to the current, and its ratio is the inductance (represented by three, also known as the self-inductance coefficient). L=Inverse l The inductance is mainly related to the number of turns (number of turns) of the coil, the winding method and the material of the magnetic core. The more turns of the coil and the denser the coil, the greater the inductance. Magnetic: The inductance of the tag is larger than the inductance of the non-magnetic core. The higher the permeability of the inductor core, the greater the inductance. 
    ②Unit of inductance: The basic unit of inductance is Henry (referred to as Henry), which is represented by the letter H. In addition, there are millihenries (mH) and microhenries (¨H). The relationship between them is: lH=103mH=106″H=109nF.  
    (2) Quality factor: The quality factor is also called the Q value, which is the ratio of the energy storage and energy consumption of the inductor. The higher the quality factor, the lower the losses and the higher the efficiency of the inductor. 
    (3) Rated current: The rated current is the maximum current that is allowed to pass through the inductor during normal operation. 
    (4) Distributed capacitance: Distributed capacitance refers to the capacitance that exists between the turns of the coil and between the coil and the iron core. The smaller the distributed capacitance, the better its stability.


    What is the magnetoresistance effect?

    The internal resistance of the Hall element increases with the absolute value of the magnetic field, a phenomenon called the magnetoresistive effect.

    Can the resistance of a capacitor or battery be determined using any of several methods?

    1. Non-drop at the beginning of constant current discharge;
    2. Current pulse (5~30s) in specified charging state;
    3. Voltage recovery when discharge or charging current is blocked;
    4. Measurement of AC impedance at 1 kHz.

    Knowledge about thermistors

    The physical characteristics of the thermistor are represented by the following parameters: resistance value, B value, dissipation coefficient, thermal time constant, and temperature coefficient of resistance.
    Resistance value: R[Ω]. The approximate value of the resistance value is expressed as: R2=R1exp[1/T2-1/T1]. Among them: R2: The resistance when the absolute temperature is T2[K] [Ω] R1: The absolute temperature is Resistance at T1[K] [Ω]
    B: B value [K] B value: B [k] B value is a function of resistance change between two temperatures, the expression is: B=InR1-InR2=2.3026(1ogR1-1ogR2)1/T1-1/ T21/T1-1/T2. Among them: B: B value [K] R1: Resistance when the absolute temperature is T1 [K] [Ω] R2: Resistance when the absolute temperature is T2 [K] [Ω] Dissipation coefficient : δ[mW/℃]
    The dissipation coefficient is the ratio of the electrical power consumed by the object to the corresponding temperature rise value δ=W/T-Ta=I²R/T-Ta where: δ: dissipation coefficient δ[mW/℃]W: electricity consumed by the thermistor Work [mW] T: temperature value after reaching thermal equilibrium [°C] Ta: room temperature [°C] I: current value on heating thermistor at temperature T [mA] R: current value on heating thermistor at temperature T Current value [KΩ] When measuring temperature, care should be taken to prevent the thermistor from heating up due to heating.
    Thermal time constant: τ[sec.] Thermistor’s temperature changes due to the step effect under zero energy conditions. The time required for the temperature to change 63.2% between the initial and final values ​​is Thermal time coefficient τ.
    Temperature coefficient of resistance: α〔%/℃〕α is a coefficient that indicates the degree of change of the resistance value of the thermistor when the temperature changes by 1ºC [namely the rate of change]. It is expressed by α=1/R·dR/dT, and the calculation formula is : α=1/R·dR/dT×100=-B/T²×100 Among them: α: Resistance temperature coefficient [%/℃] R: Resistance value at absolute temperature T [K] [Ω] B: B value [K]

    How to automatically set block parameters?

    In order to correctly set the block call parameters, the program editor of STEP 7 provides the user with the function of program blocks to receive parameters in the hardware configuration and connection configuration. 
    When assigning parameter values ​​to blocks in the user program, follow these steps:
    1) Call the block for communication in the program editor, such as SFC 15 “PUT”, do not enter the connection parameter ID temporarily. 
    2) Right-click on the called block. 
    3) Execute the “Connect” command in the shortcut menu that appears. 
    4) In the “Block Parameters for Connections” dialog box that appears (as shown in the figure), select a connection in the “Available Connections” list. Under “Block Parameters For:” appears for this communication Block parameters for the block. 
    5) Click the “OK” button, the block parameter ID value W#16#1 generated during configuration will automatically appear in the called block. Click the “Properties” button in the figure to display the connection properties dialog box. Click the “New Connection” button, in the “New Connection” dialog box that appears, you can establish a new connection. Click the “Change partner” button, and in the “Change connection partner” dialog box that appears, you can change the communication partner in the connection.

    What are the advantages of using the Zebeck effect?

    The Seebeck effect can be used not only to make temperature sensors, but also to convert thermal energy into electricity.
    This power generation method is a new fully static direct power generation method, which has the advantages of compact structure, reliable performance, no noise, no wear, no leakage, and flexible movement during operation.

    Briefly describe the pulse oximeter?

    Oxygen saturation is the percentage of oxyhemoglobin (HbO2) bound by oxygen in the blood to the total bound hemoglobin (HbO2 Hb), that is, the concentration of blood oxygen in the blood.
    It is an important physiological parameter that reflects whether the respiratory function and oxygen content of the human body are normal, and it is also an important physiological parameter that shows whether the various tissues of our body are healthy.
    Pulse oximeter is a new type of medical instrument that is non-invasive and can continuously monitor the arterial oxygen saturation of the human body.
    Pulse oximeters use non-invasive techniques to measure the amount of oxygen in the blood. A more accurate name for the measurement is blood oxygen saturation, or SpO2. It is used to distinguish the blood oxygen concentration measured by other blood oximeters.
    At present, most of the pulse oximeters produced and used clinically at home and abroad are double-beam transmission oximeters.


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