Simply put, devices that require an (electrical) source are called active devices, and devices that do not require an (electrical) source are passive devices. Active devices are typically used for signal amplification, conversion, etc., passive components are used for signal transmission, or "signal amplification" by directionality. Capacitance, resistance, and inductance are passive devices, and ICs, modules, etc. are all active devices. (Commonly speaking, it is the active components, such as triodes, that require a power supply to display their characteristics. A passive component can be displayed without the use of a power supply.) Simple definition of passive components If an electronic component does not have any form of power supply inside it, the device is called a passive device. From the perspective of circuit properties, passive components have two basic characteristics: (1) Self-consumption of electrical energy, or conversion of electrical energy into other forms of other energy. (2) Just input the signal and it will work normally without external power supply. Basic definition of active devices If an electronic component has a power supply inside it, the device is called an active device. In terms of circuit properties, active devices have two basic features: (1) It also consumes electricity itself. (2) In addition to the input signal, there must be an external power supply to work properly. It can be seen that the active device and the passive device have different working conditions and working modes for the circuit, which must be paid attention to in the learning process of electronic technology. Common passive electronic devices Passive devices in electronic systems can be classified into circuit-based devices and connected devices according to the circuit functions they perform. 1, circuit type device (1) diode (diode) (2) Resistor (resistor) (3) Resistor network (4) Capacitor (5) Inductor (6) Transformer (transformer) (7) Relay (relay) (8) button (key) (9) buzzer, speaker (speaker) (10) switch 2, connected devices (1) connector (connector) (2) socket (shoket) (3) Connecting cable (line) (4) Printed circuit board (pcb) Common active electronic devices Active devices are the main components of electronic circuits. From physical structure, circuit functions and engineering parameters, active devices can be divided into discrete devices and integrated circuits. 1, discrete devices (1) Bipolar transistor, generally referred to as triode, bjt (2) Field effect transistor (field effecTIve transistor) (3) Thyristor (thyristor), also known as thyristor (4) Semiconductor resistors and capacitors - resistors and capacitors fabricated using integrated technology for use in integrated circuits. 2, analog integrated circuit devices Analog integrated circuit devices are integrated circuit devices used to process analog voltage or current signals that vary continuously over time. Basic analog integrated circuit devices generally include: (1) Integrated operational amplifier (operaTIon amplifier), referred to as integrated op amp (2) Comparator (3) Logarithmic and exponential amplifiers (4) Analog multiplier/divider (mulTIplier/divider) (5) Analog switch circuit (analog switch) (6) pll circuit (phase lock loop), that is, phase-locked loop circuit (7) Integrated voltage regulator (voltage regulator) (8) Reference source (9) Waveform generator (10) Power amplifier 3. Digital integrated circuit devices (1) logic gate circuit (2) Flip-flop (3) Register (register) (4) Decoder (5) data comparator (comparator) (6) driver (7) counter (counter) (8) shaping circuit (9) Programmable logic device (pld) (10) Microprocessor (mpu) (11) Microcontroller (mcontroller) (12) dsp device (digital signal processor, dsp) Passive components are mainly resistors, inductors, and capacitors. Their common feature is that they can operate when there is no signal in the circuit. 1, the resistance When a current passes through a conductor, the property of the conductor internal resistance to block the current is called a resistance. A component that acts as a choke in a circuit is called a resistor, or a resistor. The main purpose of the resistor is to step down, divide or shunt, and use it as load, feedback, coupling, isolation, etc. in some special circuits. The symbol of the resistor in the circuit diagram is the letter R. The standard unit of resistance is ohms, denoted as R. Commonly used are thousands of ohms KΩ, megohm MΩ. IKΩ=1000Ω 1MΩ=1000KΩ 2, the capacitor Capacitors are also one of the most common components in electronic circuits, and they are components that store electrical energy. The capacitor consists of two layers of insulating material sandwiched between two identical conductors. When a voltage is applied across it, a charge is stored on the capacitor. Once there is no voltage, as long as there is a closed loop, it will release power. Capacitors block DC through in the circuit, allowing AC to pass, and the higher the frequency of the AC, the stronger the ability to pass. Therefore, capacitors are commonly used in circuits, bypass filtering, feedback, timing, and oscillation. The letter code of the capacitor is C. The unit of capacitance is Farad (denoted as F), and commonly used are μF (micro method), PF (ie μμF, pico method). 1F=1000000μF 1μF=1000000PF The characteristics of a capacitor in a circuit are non-linear. The impedance to current is called capacitive reactance. The capacitive reactance is inversely proportional to the capacitance and the frequency of the signal. 3, inductance Inductors, like capacitors, are also energy storage components. The inductor is generally made of a coil. When an alternating voltage is applied across the coil, an induced electromotive force is generated in the coil, hindering the change in current through the coil. This hindrance is called inductive resistance. The inductive reactance is proportional to the amount of inductance and the frequency of the signal. It does not hinder DC power (regardless of the DC resistance of the coil). Therefore, the role of the inductor in the electronic circuit is: choke, voltage transformation, coupling and cooperation with the capacitor for tuning, filtering, frequency selection, frequency division, and the like. The code of the inductor in the circuit is L. The unit of inductance is Henry (denoted as H), commonly used are millihenry (mH), microhenry (μH). 1H=1000mH 1mH=1000μH Inductors are typical components of electromagnetic induction and electromagnetic conversion. The most common application is transformers. Active device Active components are the core of electronic circuits, and all oscillation, amplification, modulation, demodulation, and current conversion are inseparable from active components. Electronic tube The electron tube is also known as a vacuum tube, so it is also called an electric vacuum device. The electron tube has an anode and a cathode regardless of its polarity or multipole. The cathode emits electrons to the anode under the action of an external power source. The external power supply can be applied directly to the cathode or to another heating filament. It is because of the existence of this external power supply, and is collectively referred to as an active device. The electron tube is the earliest active electronic component, divided into diode, triode and multipole tube. With the development of electronic technology, the electron tube has given way to transistors and integrated circuits because of its large size, heavy weight, and large power consumption. However, in many cases, the tube continues to function. A device that can independently exhibit its external characteristics without relying on the presence of an external power source (DC or AC) is a passive device. Beyond the active devices. The so-called "external characteristic" is a measure of the relationship of the device, although the relationship between voltage or current, electric field or magnetic field pressure or velocity is used to describe the relationship. The external characteristics of passive components have nothing to do with whether they exist as a source of motivation. The concept of passive and active is not only found in electrical components, but also in the fields of mechanics, fluids, thermodynamics, acoustics, etc. Transparent Led Film Screen P20 Since its establishment, it has been focusing on the application field of LED transparent flexible film screen. 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