Utsource-Electronic

  In maintenance, design and experiment or trial production, the replacement of transistors is often encountered. If the principle of replacement (substitution) of transistors is mastered, the work will be effective at the beginning. Its replacement (substitution) principles can be divided into three types: the same type, similar characteristics, and similar appearance. One, the same type 1. The materials are the same. That is, the germanium tube is replaced by a germanium tube, and the silicon tube is replaced by a silicon tube. 2. The polarity is the same. That is, NPN type pipe is replaced by NPN type pipe, and PNP type pipe is replaced by PNP type pipe. 3. The actual model is the same, but the labeling method is different, such as: D1555 is the same as 2SD1555; R1201 is the same as GR1201; 3DG9014 is the same as 9014; the patch tube uses the code to represent the original model, etc. However, it does not rule out that the parameters of the same model vary greatly due to differe...

Gas sensors  are mainly used to detect a specific gas and measure whether the gas exists near the sensor, or the content in the air near the sensor. Therefore, gas sensors are often indispensable in safety systems. These sensors can provide security systems with information on flammable, flammable and toxic gases, as well as the consumption of oxygen in the area, the ratio of carbon dioxide. Common gas sensors include electrochemical gas sensors, catalytic combustion gas sensors, semiconductor gas sensors, infrared gas sensors, etc. Different types of sensors have different performances, usage methods, applicable gases and applicable occasions due to different principles and structures. Today, Instrument Control Jun will list the common types of gas sensors for everyone, hoping to be helpful to everyone. Electrochemical gas sensor A considerable part of flammable, toxic and harmful gases, such as hydrogen sulfide, nitrogen monoxide, nitrogen dioxide, sulfur dioxide, carbon monoxide...

In electronic circuits, capacitors  are used to block DC through AC, and are also used to store and release charges to act as filters to smooth output pulsating signals. Small-capacity capacitors commonly used in high-frequency circuits such as radios, transmitters, and oscillators. Large-capacity capacitors are often used for filtering and storing charges. And there is another feature. Generally, capacitors above 1μF are electrolytic capacitors, while capacitors below 1μF are mostly ceramic capacitors. Of course, there are others, such as monolithic capacitors, polyester capacitors, and small-capacity mica capacitors. Electrolytic capacitors have an aluminum shell, which is filled with electrolyte, and leads out two electrodes as positive (+) and negative (-) poles. Unlike other capacitors, their polarity in the circuit cannot be wrong, while other capacitors are No polarity. Connect the two electrodes of the capacitor to the positive and negative poles of the power supply. After ...

 Introduction to impedance Impedance and resistance have the same unit, both are Ω. Resistance has an obstructive effect on current, and similarly, impedance has an obstructive effect on current. Impedance can be any combination of resistance, capacitance, and inductance that hinders the current. Since the impedance of the capacitor to the direct current is infinite, and the impedance of the inductance to the direct current is zero, the impedance is more used to describe the obstructive effect of the current in the AC circuit. High impedance refers to a large impedance value, and low impedance refers to a small impedance value. What is a horn The trumpet is divided into several different musical instruments, a kind of wind instrument, with thin upper part and thick lower part, mostly made of copper. The other is a modern electro-acoustic component, whose function is to convert electrical signals into sound, which is also called a speaker. It can also be used to describe someone wh...

TDA7294 contains a variety of functions such as pre-op amplifier, final power amplifier, temperature protection, short circuit protection, and mute control. The power amplifier circuit composed of TDA7294 has simple peripheral circuits, easy to manufacture, high input impedance (20K Ω ), input sensitivity 750mV, voltage gain 32dB, power supply voltage range ± 25~40V, quiescent current 50mA. When the load impedance is 8 Ω , the output power can reach 100W. In actual production, a large enough heat sink and a power supply with sufficient power should be ensured. If you need to increase the voltage gain of the overall circuit, you can change the ratio of R3 to R2. Voltage gain: A=20lg (R3/R2) dB. Don ’ t pursue too high voltage gain, so as not to cause uncontrollable self-oscillation. To have a high voltage gain, you need to add a pre-amplifier. As shown in the figure below, it is an easy-to-make 100-watt power amplifier circuit composed of TDA7294.

pc817 is a type of optocoupler. The optocoupler (opTIcalcoupler, abbreviated as OC in English) is also known as opto-isolator or optocoupler, abbreviated as optocoupler. It is a device that transmits electrical signals through light.   The working principle of pc817: PC817 is a device that encapsulates infrared light emitting devices, infrared light receiving devices and signal processing circuits in the same socket. When the input electrical signal is applied to the input light emitting device LED, the LED emits light, the light receiving device receives the light signal and converts it into an electrical signal, and then directly outputs the electrical signal, or amplifies and processes the electrical signal to a standard digital level output. The conversion and transmission of "electricity-optical-electricity" are realized. Light is the transmission medium, so the input end and the output end are electrically insulated, which is also called electrical isolation.   The dete...

TL431 is a precise voltage regulator integrated device. Because TL431 has high control voltage accuracy and relatively small temperature coefficient, it can provide accurate reference voltage. This device can also be seen in switching circuits such as battery car chargers and induction cooker circuits. This kind of precision voltage reference integrated circuit is widely used. Now I would like to give my friends a brief introduction to this integrated circuit commonly known as a voltage regulator.   Introduction to TL431 This kind of integrated circuit has three forms, one is like a plastic-encapsulated triode, and its package form is T0-92A. It has three pins, with the plane facing itself, the first pin from the far left is represented by R, which is the voltage sampling pin; the second pin is represented by A, called the anode; the rightmost lead The foot is denoted by K, which is the control terminal. The second type is in the form of integrated patch, and its package is SOJ-8 t...