Hdmi male connector pcb
Inductance in a circuit is usually represented by "L" with a number. For example, L6 refers to the inductance numbered 6.Inductance coils are made by winding insulated conductors to an insulated skeleton for a certain number of turns.Dc can pass through the coil, dc resistance is the resistance of the wire itself, the pressure drop is very small;When the ac signal passes through the coil, self-induced electromotive force will be generated at both ends of the coil. The direction of self-induced electromotive force is opposite to that of the applied voltage, which prevents the passage of ac. Therefore, the inductance characteristic is to pass through dc resistance ac.Inductance and capacitance can constitute an oscillating circuit in a circuit.Inductance generally has direct standard method and color standard method, color standard method and resistance similar.
Effect: the main characteristic of the diode is unidirectional conductivity, that is, under the action of positive voltage, the conductive resistance is very small;The conduction resistance is maximum or infinite under the action of reverse voltage.Because of the characteristics of diodes, cordless telephone is often used in rectification, isolation, voltage stabilization, polar protection, coding control, frequency modulation and noise control.The crystal diodes used in the telephone can be divided into rectifier diodes (such as 1N4004), isolation diodes (such as 1N4148), schottky diodes (such as BAT85), light emitting diodes and voltage stabilizing diodes.
Identification method: the identification of diode is very simple. The n-pole (negative pole) of small power diode is mostly marked with a color ring on the diode surface. Some diodes also use the special symbol of diode to represent P pole (positive pole) or N pole (negative pole).The positive and negative electrodes of the light-emitting diode can be identified from the length of the pin.
Test precautions: when using digital multimeter to test the diode, the red pen is connected to the positive pole of the diode, and the black pen is connected to the negative pole of the diode.
The voltage stabilizing diode is usually represented by "ZD" with a number in the circuit. For example, ZD5 represents the voltage stabilizing tube numbered 5.
Voltage stabilizing diode principle: the characteristic of voltage stabilizing diode is that the voltage at both ends basically remains unchanged after breakdown.In this way, when the stabilizer is connected to the circuit, the voltage at both ends of the load will remain basically the same if the voltage at each point in the circuit changes due to the fluctuation of power supply voltage or other reasons.
Fault features: the fault of voltage stabilizing diode is mainly manifested in open circuit, short circuit and unstable voltage stabilizing value.Among the three faults, the former fault shows the increase of power supply voltage;The latter two failures manifest as the power supply voltage drops to zero or output instability.
Varactor diode is a special kind of diode specially designed according to the principle that the capacity of the junction capacitance of the "PN junction" inside the ordinary diode varies with the applied reverse voltage.The varactor diode is mainly used in the high frequency modulation circuit of mobile phone or landline in cordless telephone.In the working state, the modulation voltage of the varactor diode is generally added to the negative pole, so that the internal junction capacitance of the varactor diode changes with the modulation voltage.The failure of the varactor diode is mainly manifested as leakage or poor performance:
When leakage occurs, the high frequency modulation circuit will not work or modulation performance will deteriorate.When the variable-capacitance performance becomes worse, the work of the high frequency modulation circuit is not stable, so that the high frequency signal after modulation is sent to the other party is received by the other party, resulting in distortion.When one of the above situations occurs, the same type of varactor diode should be replaced.
Comparison of fet and transistor (1) the fet is a voltage control element while the transistor is a current control element.The effector should be used when only a small amount of current is allowed from the signal source.Under the condition that the signal voltage is low and more current is allowed from the signal source, the transistor should be chosen.(2) the field effect tube conducts electricity with most carriers, so it is called a monopole device, while a transistor conducts electricity with a few carriers even if it has a majority of carriers.It is called a bipolar device.(3) the source and drain poles of some field effect tubes can be used interchangeably, the gate pressure can be positive or negative, and the flexibility is better than the transistor.(4) the field effect tube can operate at very small current and very low voltage, and its manufacturing process can easily integrate many field effect tubes into a silicon chip. Therefore, field effect tube has been widely used in large-scale integrated circuits.
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