The three -pole work principle is explained in details. After reading these 4 points, I understand!

1 thought on “The three -pole work principle is explained in details. After reading these 4 points, I understand!”

  1. The triode, the full name should be a semiconductor triode, also known as bipolar crystal tube and crystal triode. It is a semiconductor device with current controlling current. Essence The following is the principles of the triode. Friends who do n’t know with Xiaobian will take a look.

    The principle of triode pipe
    . The current exile
    The analysis below is only for the NPN silicon triode. IB; Call the current from the set electrode C to the transmitting polar E as the setting electrode current IC. The direction of these two currents flows the emitter, so a arrow uses an arrow to represent the direction of the current. The amplification effect is: the collector current is controlled by the base current (assuming that the power supply can provide a current with a large current), and the change of the base current is small, which will cause a large change in the set current, and the change will change Meet a certain proportional relationship: the change in the current electrode current is the β times of the base current change, that is, the current changes are amplified and the β times, so we call the β as the amplification multiple of the triode (β is generally greater than 1, for example, tens of tens Hundreds of). If we add a small signal to the base pole and the emission pole, this will cause changes in the base current IB. After the changes in IB are amplified, it will cause great changes in IC. The collector current IC flows through a resistor R, so if the voltage calculation formula U = R*i can be counted, the voltage up voltage will change greatly. The amplified voltage signal.

    . The bias circuit
    When the triode is used in the actual amplifier circuit, it also needs to add a appropriate bias circuit. There are several reasons for this. First of all, first of all. It is due to the non -linearity of the triode BE knot (equivalent to a diode), the basal electrode current must be generated after the input voltage is large to a certain extent (for silicon tube, 0.7V is often taken). When the voltage between the basis and the emission pole When less than 0.7V, the base electrode current can be considered to be 0. But the signal to be enlarged in fact is often far smaller than 0.7V. If you do not add bias, such a small signal is not enough to cause changes in the base current ( Because when it is less than 0.7V, the base current is 0). If we add a suitable current to the base of the triode in advance (called the bias current, the resistance RB in the figure above is used to provide this current, so It is called the base bias resistor), so when a small signal is superimposed with this bias current, the small signal will cause changes in the base current, and the change of the base current will be amplified and the set will be in the set. Output on the electrode. Another reason is the requirements of the output signal range. If there is no bias, then only the increased signal amplification, and the reduced signal is invalid. Decreased). Add bias to make the setting electrode a certain current in advance. When the input base current changes hours, the collector current can be reduced; when the input base current increases, the collector current current is Increased. This reduced signal and enlarged signal can be enlarged.
    . The switching function
    Themuity of the triode. Restrictions (RC is The fixed value, then the maximum current is U/RC, where U is the power supply voltage), and the collector current cannot be increased infinitely. When the base current increases, when the current electrode current can not continue to increase Saturation state. Generally, the criterion for determining whether the transistor is saturated is: IB*β> IC. After entering the saturation state, the voltage between the hub and the transmitting pole of the triode will be very small, which can be understood as a switch closed. In this way, we can then we can Take the transistor as a switch: When the base current is 0, the current of the triode set electrode is 0 (this is called the triode dead), which is equivalent The switch is closed. If the triode is mainly working in the deadline and saturation, then we generally call it the switch tube.

    . The working status
    If in the above figure, we will be in the above figure, and we will be in the above figure. The resistance RC is replaced by a light bulb, so when the base current is 0, the collector current is 0, and the light bubbles are extinguished. If the base current is relatively large (the current that flows through the light bulb is divided by the amplification multiple of the triode), the triode pipe is the triode. The saturation is equivalent to the switch closed, and the bulb is on. Since the control current only needs to be a little larger than the β of the bulb current, a small current can be used to control a large current. Slowly increased from 0, then the brightness of the light bulb will also increase (before the triode is not saturated).
    The work principle of the triode switch circuit
    , The base limit flow resistor R and the power supply GB. The VT uses NPN type small power silicon tube 8050, and its maximum allowable current ICM can reach 1.5A to meet the requirements of the motor to take over. M uses a small DC motor with a working voltage of 3V, and the corresponding power supply GB is also 3V.
    . How to determine the VT base limit flow resistor R?
    Capons according to the current distribution effect of the triode switch circuit, enter a weaker current IB in the base pole, and you can control the collector current IC. Variety.

    I assume that the VT current seal coefficient HFE≈250, the collector current IC = 1.5A when the motor starts. ) × 2 = 12mA.
    In Figure 1 circuit, the operating current during the electric vehicle is about 500mA. At this time, the voltage of the power supply (with two batteries 5 batteries) is reduced to 2.4V, VT base-voltage VBE≈0.9 between the launch pole is V.
    In the law of the ohm, the resistance value of the VT base limit flow resistor is R = (2.4-0.9) v/12ma≈0.13kΩ. Considering that when VT is large in IC, HFE should be reduced, and the resistance value R is smaller, and it is 100Ω.

    to start the motor more reliable, R can even reduce to 51Ω. When debugging the transistor switch circuit, the control switch S is connected, and the motor should be able to start itself. Measure the VT collector — the voltage of the transmitting pole VCE ≤ 0.35V, indicating that the triode is saturated and turned on. VT is overheated and damaged.
    The tritinal pipes are often used in various circuits in daily life, using switch circuits, etc., are also materials necessary for decoration. When it comes to decoration, whether there is a guarantee for the quality problems of these materials and whether the project meets the industry standards. These problems are the most concerned about the decoration owners. If these concerns, we can apply for the Tuba Rabbit Insurance for free. There are professional decoration here. The quality inspection team can help us quickly defend our rights when they encounter problems! Click on the application to make our decoration more guaranteed!

    The above is the principle of triode work introduced by the editor. Help you. For more information about the working principle of the triode, please continue to pay attention to Tuba Rabbit learning decoration.

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