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  • Ten Daily Electronic Common Sense-Section 130

    What is included in the signal channel section?

    The input of the measured signal channel 1 and the measured signal channel 2 are used to access the signal we want to measure, that is, the input terminal of the measured signal. Here, because it is a dual-trace oscilloscope, there are two channels, and two signals can be connected at the same time for comparison and observation. This is the characteristic of the dual-trace oscilloscope.
    If it is a four-trace oscilloscope, there are four signal input channels. If it is a single-trace oscilloscope, there is only one input channel. It should be noted that different oscilloscopes have different maximum voltage amplitudes of their input channels. Typically 400V or 300V, and even 250V, in this case 300V (peak-to-peak). If the peak value of the input signal voltage exceeds this value, the input channel of the oscilloscope may be damaged, which requires readers to pay special attention. the
    In addition, the input channels of some oscilloscopes also mark the values of their equivalent input capacitance and equivalent input resistance. For a general-purpose oscilloscope, its equivalent input capacitance is generally 20pF, and its equivalent input resistance is generally lMΩ.

    What are the two major categories of frequency measurement lines?

    One is to directly read the frequency value, that is, the induced potential output by the sensor is amplified and shaped, and then sent to the counter for display or directly displayed by a digital frequency meter.
    The other is to use the comparison method to read the frequency value, that is, compare the frequency of the induced potential output by the sensor with the frequency value issued by a standard oscillator. Adjust the frequency value of the standard oscillator to be equal to the frequency of the sensor. At this time, the frequency displayed by the standard oscillator is the measured frequency value.

    What are the cold pressed indium sealing processes?

    1. The treatment of the indium sealing surface requires careful polishing and cleaning. Then store in clean and dry conditions to prevent contamination during storage.
    2. Since the introduction of impurities will increase the saturated vapor pressure of indium, the introduction of impurities should be reduced. In order to maintain the good ductility of indium, indium needs to be pretreated, and pure indium melted in vacuum is often used as the sealing material.
    3. Pressure seal.
    4. Thermal indium sealing

    What are the four typical methods of constructing a semiconductor strain gauge?

    • Semiconductor strain gauges have the following four typical composition methods:
      1. ordinary semiconductor strain gauges;
      2. compensation semiconductor strain gauges;
      3. baseless semiconductor strain gauges;
      4. metal substrates Semiconductor pressure diaphragm.

    What are the characteristics of the MSCAN module?

    • Implementation of CAN protocol version 2.0A/2.0B: standard and extended data frames, 0-8B data length, programmable bit rate up to 1Mb/s, and support for long-range frames.
    • 5 receiving buffers with FIF0 storage mechanism.
    • 3 send buffers with internal prioritization using the “local priority” concept.
    • The flexible maskable identifier filter supports 2 full-size (32-bit) extended identifier filters or 4 16-bit filters or 8 8-bit filters.
    • Programmable wake-up function with integrated low-pass filter.
    • Programmable loopback mode supports self-test operation.
    • Programmable monitoring mode is used for CAN bus monitoring.
    • Programmable bus break-away recovery function.
    • Independent signal and interrupt functions apply to all CAN receiver and transmitter error states (alarm, error critical state, bus off).
    • Programmable MSCAN clock source, using bus clock or oscillator clock.
    • The internal timer provides time tags for received and sent messages.
    • Sleep, shutdown and MSCAN enable three low-power modes.
    • Global initialization of configuration registers.

    What is magnetic flux?

    The number of magnetic force lines passing through a certain cross-sectional area in the magnetic field is called the magnetic flux passing through this surface, expressed in country. The unit of magnetic flux is Weber (wb).

    How does the TQ2440 serial port and PC transfer data to each other?

    After logging in to the terminal through the serial port, you can use the commands rz and sz to transfer files to and from the PC through the serial port.
    After the PC machine compiles the application program, use the rz command to download the program to the development board for testing. You can also use the sz command to transfer the files in the development board to the PC.

    What is the problem with the probe line?

    1. The common terminal is suspended: when testing the waveform of the circuit under test, it is often seen that the measured waveform is erratic. At this time, check whether the alligator clip at the common end of the oscilloscope probe is connected to the circuit under test. If it has been accurately connected to the relevant points of the circuit under test, the measured waveform is still erratic. At this time, it is necessary to check whether the common terminal connection of the probe is connected to the alligator clip.
    2. The crocodile clip of the probe line is disconnected: If the crocodile clip of the common end of the oscilloscope probe has been clipped to the relevant position of the circuit under test. The measured waveform is erratic, so it is necessary to consider whether the alligator clip at the common end of the probe is connected to the connection line. It appears that the alligator clip on the common end of the oscilloscope probe is connected to the wire, but in fact it may be disconnected. Why is this? Because the alligator clip on the common end of the oscilloscope probe often needs to be replaced on the circuit under test. It is inevitable to bend repeatedly, and there may be disconnection between the alligator clip and the connection. The most common breakout point is where it is subjected to the greatest mechanical stress, the bendable portion near the soldered portion where the wire connects to the alligator clip. Once the wire breaks during bending, the wire doesn’t necessarily come off the alligator clip due to the alligator clip sheath. The illusion created is that the wires and alligator clips are still connected. At this time, you can use a multimeter to test whether it is connected. If the multimeter at hand is inconvenient, you can also pull the alligator clip and connection by hand. If it pulls apart with a slight tug, the wire and alligator clip are actually disconnected. At this time, re-solder the connection wire and the alligator clip.
    3. Poor contact: If the alligator clip at the common end of the oscilloscope probe is well connected to the wire, the measured waveform is still erratic. At this time, it is necessary to consider whether the connection between the common end of the oscilloscope probe and the circuit under test is poor. The reason for this phenomenon is that the alligator clip at the common end of the probe is not accurately clamped on the corresponding connection point of the circuit under test. The first reason for not connecting correctly may be that the teeth of the alligator clip are not biting on the relevant point of the circuit, this may be due to the geometry of the alligator clip, or it may be just caught in the gap between the teeth of the alligator clip. The second reason may be that the teeth of the alligator clip are oxidized and the contact resistance is too large. Or the position where the alligator clip is clamped has a relatively large contact resistance, and the relevant position needs to be cleaned at this time.

    What is the working system for safe production of electrical equipment commissioning?

    1. Electrical commissioning personnel should regularly study the “Electrical Industry Safety Work Regulations” issued by the former Ministry of Energy, and are required to pass the examination.
    2. On-site safety activities should be carried out once a week, and documents such as accident notification and anti-accident measures should be studied.
    3. Electrical commissioning personnel should learn how to first aid people who get an electric shock, and be able to carry out practical operations.
    4. On-site work must conscientiously implement the work ticket system.
    5. For any debugging work that needs to be powered on, two or more personnel must cooperate to carry out the work.
    6. If the work tasks are not clear, the location of the test equipment or the surrounding environment is not familiar, the test items and standards are not clear, and the division of labor is not clear, the work shall not be carried out.

    What is the output voltage swing?

    The output voltage swing refers to the maximum amplitude that the output voltage can achieve within the range that meets the linearity requirements.
    As mentioned earlier, the output voltage swing is interrelated with the power supply voltage, circuit structure, device size, speed, and gain.
    At present, the power supply voltage of integrated circuits is getting lower and lower, and the requirements for gain are getting higher and higher. Circuits are operating faster and faster, and these are the limiting factors for swing.
    Therefore, how to make the output voltage swing meet the requirements of the system is a key consideration in the design of the op amp.


    DISQUS: 1