What is a circuit? Circuits are paths through which current flows, or electronic circuits, and are made up of electrical equipment and components (appliances) that are connected in a certain way. Such as resistors, capacitors, inductors, diodes, transistors, power supplies and switches, etc., constitute the network. I believe that for those who have the need for this, they must be very interested in knowing about electric circuits. Don't worry, in order to help you further understand what is a circuit and other related knowledge, the following I will be around the circuit to explain to you one by one.
What is a circuit
The actual circuit is the totality of certain electrical devices, components, switches, wires, etc. connected in a certain way to provide a path for the flow of current. The concept is somewhat abstract, and three typical circuits are described below.
(1) Simple Lighting Circuit
When a light bulb is connected to the two electrodes of a battery through a switch, wire, the bulb glows, which indicates that there is a flow of current in the circuit.
(2) Circuit for supplying power to an electrical system
Coal is burned in the boiler of a power plant, so that the water gains heat energy and turns into high-pressure steam. The high pressure steam drives the turbine to rotate, converting the energy it has into mechanical energy. The turbine drives a generator that converts the mechanical energy into electrical energy. Electrical energy through the transmission lines and transformers to the power sector into various forms of energy, this energy transfer and conversion process is completed through the circuit.
(3) computer circuits
You must be familiar with the computer! It has a lot of functions, the powerful, no need to introduce, you will cite a variety. For example, it can put the information on the CD-ROM, through the monitor and speakers into the image and sound signals, so that you can watch movies through the computer, the function of this processing information is also realized through the circuit.
Circuit Composition
A circuit consists of four main parts: the power supply, the switch, the connecting wires, and the appliances. The actual application of the circuit are more complex, therefore, in order to facilitate the analysis of the essence of the circuit, usually using symbols to indicate the composition of the circuit of the actual original and its connecting lines, that is, drawn into the so-called circuit diagram. Which wires and auxiliary equipment collectively known as the intermediate link.
A power supply is a device that provides electrical energy. The function of a power supply is to convert non-electrical energy into electrical energy. For example, the battery is to convert chemical energy into electrical energy; generator is to convert mechanical energy into electrical energy. Since there are many types of non-electrical energy, there are many ways to convert it into electrical energy. The power supply is divided into two kinds of voltage and current sources, only the same size of the voltage source is allowed to be connected in parallel, and the same is only allowed to be connected in series with the same size of the current source, the voltage source can not be short-circuited, the current source can not be disconnected.
The various devices that use electrical energy in the circuit are collectively called loads. The function of the load is to transform electrical energy into other forms of energy. For example, the furnace to transform electrical energy into thermal energy; electric motor to transform electrical energy into mechanical energy, and so on. Usually used lighting, household appliances, machine tools, etc. can be called load.
The connecting wire is used to connect the power supply, load and other auxiliary equipment into a closed loop, playing a role in the transmission of electrical energy.
Auxiliary equipment
Auxiliary equipment is used to realize the control of the circuit, distribution, protection and measurement. Auxiliary equipment includes various switches, fuses, ammeters, voltmeters and measuring instruments.
The role of the circuit
The circuit is designed to achieve a certain purpose, it has a variety of forms, but in terms of its role, can be categorized into two categories:
(1) the realization of the transmission of electrical energy, distribution and conversion.
(2) the realization of the transmission and processing of electrical signals.
Methods to improve the anti-interference ability of electronic circuits
First, reduce the noise from the power supply
The power supply provides energy to the system at the same time, but also its noise added to the power supply supplied. Circuits in the microcontroller reset line, interrupt line, as well as some other control lines are most susceptible to external noise interference.
Strong interference from the power grid enters the circuit through the power supply. Even in battery-powered systems, the battery itself has high-frequency noise. Analog signals in analog circuits are more resistant to interference from the power supply. Therefore, the design of the power supply to take certain anti-interference measures: (such as input power and power equipment power lines separate; the use of isolation transformers; the use of low-pass filters; the use of independent function block separate power supply, etc.).
Second, to reduce the distortion in the signal transmission
Microcontrollers are mainly manufactured using high-speed CMOS technology. Signal input static input current in 1mA or so, input capacitance of 10pF or so, the input impedance is quite high. High-speed CMOS circuit outputs have considerable load capacity, that is, a large output value, the output of a gate through a very long line to the input impedance of the input is quite high, the reflection problem is very serious. It causes signal distortion and increases system noise. When Tpd>Tr, it becomes a transmission line problem, and signal reflection, impedance matching, etc. must be considered.
The delay time of the signal on the printed circuit board is related to the characteristic impedance of the leads, i.e. to the dielectric constant of the printed circuit board material. It can be roughly assumed that the transmission speed of the signal on the printed circuit board leads is about between 1/3 and 1/2 the speed of light. The Tr (standard delay time) of logic electronics commonly used in systems composed of microcontrollers is between 3 and 18 ns.
On a printed wiring board, where the signal passes through a 7W resistor and a 25cm long piece of lead, the delay time on the wire is roughly between 4 and 20ns. In other words, the signal on the printed circuit of the shorter the better, the longest should not exceed 25cm, and the number of holes should be as small as possible, preferably no more than two.
When the rise time of the signal is faster than the signal delay time, according to the fast electronics processing. At this time to consider the impedance matching of the transmission line, for a printed circuit board on the integrated block between the signal transmission, to avoid the situation of Td>Trd, the larger the printed circuit board the system speed can not be too fast.
Printed wiring board design rules
Signal transmission on the printed circuit board, the delay time should not be greater than the nominal delay time of the device used.
Power supply circuits: generate the required power supply for various electronic circuits.
Electronic circuit: also known as electrical circuit.
Base frequency circuit, fundamental frequency, low frequency, using base frequency components.
High-frequency circuit, high-frequency, high-frequency, using high-frequency components.
Base-frequency, high-frequency hybrid circuits
Passive components: such as resistors, capacitors, inductors, diodes ... and so on, there are divided into base-frequency passive components, high-frequency passive components.
Active components: such as transistors, microprocessors ... and so on, there are base frequency active components, high frequency active components.
Microprocessor circuits: Also known as microcontroller circuits, they form the basis for computers, game consoles, (player video and audio), various home appliances, mice, keyboards, touch controls, and so on.
Computer circuits: Microprocessor circuits are advanced circuits that form desktop computers, notebook computers, handheld computers, industrial computers, various computers, and so on.
Communication circuits: Formation of telephones, cell phones, wired networks, wired transmission, wireless networks, wireless transmission, optical communications, infrared, fiber optic, microwave communications, satellite communications, etc.
Display: The display can be used to display a wide range of digital signals, such as video, audio, and video.
Display circuits: Formation of various types of displays such as screens, TVs, meters, and so on.
Optical circuits: such as solar circuits.
Motor circuits: Often used in large power supply devices, such as electric power equipment, transportation equipment, medical equipment, industrial equipment...etc.
Series circuits: the same current through all the connected devices of the connection
Parallel circuits: the same voltage applied to all the connected devices of the connection
Editor's summary: The above is what is the circuit to improve the ability of electronic circuits to improve the anti-jamming of the knowledge of the relevant methods of introduction, I hope to be able to help to the demand for friends in this area! For more information, please continue to pay attention to our website, the follow-up will present more exciting content.