月: 2022年9月

What Is a Fast Recovery Diode?

A fast recovery diode (FRD) is a PN junction diode designed for rapid switching, with capabilities far exceeding those of standard rectifier diodes in high-frequency applications ranging from a few kHz to 100 kHz. Unlike general rectifier diodes optimized for frequencies below 500 Hz, FRDs have significantly shorter reverse recovery times (t_rr), transitioning from the on state to the off state in just 50 to 100ns, compared to 5 to 10us for standard rectifiers.

Uses of Fast Recovery Diodes

Fast recovery diodes are integral in power factor correction (PFC) circuits within switching power supplies, aiming to minimize high-frequency current interference. These circuits, comprising a diode, inductor, and MOSFET, rely on FRDs to mitigate recovery current and switching noise during continuous operation. FRDs are also employed in AC/DC converters and inverter circuits for their efficiency in high-speed switching.

Structure of Fast Recovery Diodes

FRDs share the basic PN junction structure with rectifier diodes, where the anode connects to the P layer and the cathode to the N layer, allowing current to flow only in the forward direction. Innovations in FRD design, such as carrier traps near the PN junction through electron beam irradiation or noble metal diffusion, expedite hole movement across the N layer, effectively reducing t_rr.

Principle of Fast Recovery Diodes

The principle behind FRDs involves managing the movement of holes and electrons upon sudden reverse-bias application. This movement creates a recovery current flowing opposite to the forward current, which ceases once a depletion layer forms, halting the recovery current. The design of FRDs aims not only to shorten t_rr but also to ensure a gradual recovery of the current to avoid noise due to sudden convergence or ringing.

How to Choose Fast Recovery Diodes

When selecting diodes, it’s essential to differentiate among the four main types: fast recovery, general-purpose, switching, and Schottky barrier diodes, each offering unique characteristics suited to different applications:

1. Fast Recovery Diodes

Characterized by their low t_rr and high withstand voltages, typically around 800 V, with a standard forward voltage (VF) drop of approximately 2 V, though newer models feature lower VF.

2. General-Purpose Type

Used in diode bridges for rectification and overcurrent protection, these diodes have a standard VF of about 1 V and are designed for rectifying mains electricity (50/60 Hz).

3. Switching Type

Suitable for switching power supplies, offering similar VF to general-purpose types but with faster t_rr, though not as rapid as FRDs or Schottky diodes.

4. Schottky Barrier Diode

Known for swift switching and low VF, around 0.8V at high currents (10A) and 0.5V at several amperes. However, their significant reverse leakage current may lead to thermal runaway.

What Is a Pushbutton Switch?

A pushbutton switch is a switch that is turned on and off by a pushing motion with a human finger.

They are also called push-button switches. Pushbutton switches are used as human input devices for various controls. In many cases, their role is to directly turn on or off the electric current that operates the device.

There are a wide variety of shapes and sizes of actuators and mounting points. There is also a wide variety of colors when issued, with or without a light emission to indicate on/off.

Uses of Pushbutton Switches

Pushbutton switches are used in a variety of situations. Specifically, they are used as switches for operating control equipment and inputting setting conditions because they are input devices that are operated by human fingers.

Pushbutton switches are also used as input devices on operation panels of industrial machines to provide operation and stop instructions and input settings for various operating conditions. In addition, they are also useful for devices that generally use human operation as input for operation settings and turning on/off of operations, such as power on/off operations for household electrical appliances.

Principle of Pushbutton Switches

The typical construction of a pushbutton switch is one in which the connecting terminal of the switch is connected to a pushbutton and the contacts make contact when the button is pressed. Conversely, there is another type in which the connecting terminal is pressed against a spring and the contact is separated when the button is pressed.

Some switches have a mechanical locking mechanism inside the switch that keeps it in operation when pressed once. When it is time to put it back on, there are various types, such as push again, pull back, and twist types.

One of the features of pushbutton switches is that many types of illuminated switches use light to indicate whether the switch is on or off. Illuminated switches have a light source such as LED inside.

Types of Pushbutton Switches

1. Momentary Type and Alternate Type

Pushbutton switches are divided into two types in terms of contact state switching: momentary type and alternate type.

The momentary type, as the name “momentary” implies, has an “instantaneous (temporary)” mode of operation. It turns on only while the switch is pressed.

The alternate type, meaning “alternating,” switches on when the switch is pressed and remains on when the finger is released. Then, when the switch is pressed again, it switches off and remains off when the finger is removed. Each time the switch is pressed, the operation alternates between on and off.

2. Latch Type and Unlatch Type

There are two types of push switches with different mechanical actions: latch type and unlatch type.

In the latch type, the switch is held in the depressed position once it is turned on by pressing it with a finger. Then, when the switch is pressed again, it returns to its original position and is turned off.

In contrast, the unlatch type returns to its original position once the switch is pressed, whether on or off.

How to Select Pushbutton Switches

1. Illuminated/Non-illuminated Type

Pushbutton switches are devices with high ergonomic requirements because they are pressed by human fingers. The illuminated type is useful for important actuators because it provides feedback to the operator on whether the switch has been turned on or off.

2. Surface Shape

The surface shape of a switch is considered to be concave for better operability. On the other hand, flat type is easier to indicate letters and symbols.

3. Method of Operation

Select a method of operation (momentary/alternating, latching/unlatching) that is suitable for the intended use. It is also desirable to check that the force required for operation is not too large or too small and that the latch has an appropriate feel.

4. Environmental Resistance

Consideration should be given to dustproofness and waterproofness according to the environment of use. The IEC (International Electrotechnical Commission) has established an IP code as a standard for dustproof and waterproof switches.

The first number indicates dustproofness, and the second number indicates waterproofness. The higher the number, the higher the performance. Some products have a rubber “waterproof cap” covering the important parts of the product to simplify dustproof and waterproof performance.

5. Rated Current/Voltage

Since most pushbutton switches are used to open and close an electric current, it is important to know how much current and voltage they can be used up to. The guideline for this is the “rating,” which is indicated in terms of DC or AC, rated voltage, and rated current. Select a switch with a sufficient margin for the actual operating conditions.

What Is Photo IC?

Photo IC is a device that incorporates a light-receiving element that receives light and an IC that processes the signals in a single package and is a component with functions that meet the needs of the application.

Photo ICs are classified into monosilic and hybrid types according to their structure. The monosilic type, in which the light-receiving element and the signal-processing circuit are formed on the same chip, does not require wiring between the light-receiving element and the signal-processing and is highly resistant to noise.

The hybrid type consists of a light-receiving element and a signal-processing circuit on independent chips, and they are contained in a single package. Since each chip is connected by wires, the advantage is that the shape of the photosensitive element and spectral response characteristics can be optimized according to the application.

Uses of Photo IC

Photo ICs are used to detect light, and a wide variety of devices exist for different purposes. The main applications of photo ICs are as follows:

• Illuminance meters to measure the brightness of lighting and camera exposure meters
• Receivers for communication using optical fiber
• Encoder modules for detecting movement and rotation angles
• Color sensors that break down into RGB to detect color
• Photo interrupter photodetectors for object detection by light
• Distance measuring device to measure the distance to an object by means of a triangular distance measuring system

Principle of Photo IC

A photo IC consists of a photodiode, phototransistor, or PSD (Position Sensitive Detector) that receives light and generates a current, a circuit that amplifies the output current, and a signal processing circuit that uses the amplified output to process signals. The light-receiving circuit is used to amplify the output current and process the amplified output signal. A wide variety of products combining various photosensors and processing circuits are available depending on the intended use.

There are also photo ICs whose output can be obtained in frequency, although they are special devices. These consist of a photo IC and a current-to-frequency conversion circuit and feature a wide dynamic range.

Photodetectors have different spectral response characteristics depending on the device, but none of them match human visual sensitivity characteristics. The commonly used silicon photodiode has a peak sensitivity in the range of 900 nm to 1,000 nm, but the human visual sensitivity characteristic is in the range of 400 nm to 700 nm, and the peak sensitivity is around 550 nm, so the brightness signal detected by the photodiode and the brightness perceived by humans The brightness signal detected by a photodiode is different from the brightness perceived by humans.

Therefore, for applications that need to match human sensitivity, such as illuminance meters, it is necessary to correct the spectral response characteristics of photodiodes through a visual sensitivity correction filter.

Types of Photo IC

Photo ICs are available with a variety of functions and features. The main types are as follows:

1. Distance-Measuring Photo IC

Photo ICs are used to measure the distance to an object, and PSDs and photosensor arrays are used as light-receiving elements. Combined with a light emitter such as a near-infrared LED, the distance to an object is calculated based on the position of the spotlight projected from the light emitter that is reflected by the object and reaches the photosensor, using the principle of triangular ranging.

2. RGB Color Sensor

This photo IC analyzes the color of incident light by comparing the output of three photo sensors, each of which has an optical filter on its surface that allows only red (R) light to pass through, blue (B) light to pass through, and green (G) light to pass through. The output of each sensor breaks down the incident light into its RGB components, and the main application is in measuring instruments such as color illuminance meters.

3. Illuminance Sensor

These sensors are used to measure the brightness of illumination light, etc. They are photo ICs equipped with light-receiving elements that approximate human spectral response characteristics by using visual sensitivity compensation filters, etc. The main applications are illuminance meters and photographic equipment. It is mainly used in illuminance meters and exposure meters for photographic equipment.

4. Photo Sensor for Optical Communication

This is a device for receiving optical communications using optical fiber. Installed on the end face of an optical fiber, it receives transmitted optical signals and converts them into electrical signals. There are devices with a convex lens in front of the photosensor to improve light collection characteristics.

5. Photoelectric Switch

A photo IC is used to configure a photoelectric switch in combination with a light-emitting device such as an LED. Photo interrupters and photoreceivers of photo reflectors are also included in this category.

6. Photo IC for Encoder

Generally, this photo IC has a 4-channel photodiode array. It is configured to detect the direction and amount of rotation and provides 2-phase digital outputs according to the state of light input to the photodiode array. Combined with a light-emitting element, a photointerrupter with an encoder function can be easily configured.

7. Remote Control Light Receiving IC

This is a receiver IC for remote control using infrared rays and is used in remote control systems widely employed in TVs, recording devices, air conditioners, etc. It is characterized by being covered with resin having visible light cutoff characteristics and having a steep bandpass filter corresponding to the blinking frequency of the transmitter (30kHz to 40kHz). It receives the transmitter’s command signal and outputs it to the processing circuitry of the device itself.

What Is a Protocol Analyzer?

A protocol analyzer is a measuring instrument used for testing and troubleshooting during system development between devices with digital communication functions, such as PCs, or for network maintenance.

There are various places to verify and analyze digital communication lines, indoors and outdoors. For this reason, protocol analyzers are available in battery-powered types that can be used outdoors as equipment, types that are connected to a PC, and application types that are installed on a PC, allowing them to be used at different levels and in different environments.

Usage of Protocol Analyzers

Protocol analyzers are used to analyze and solve problems such as data anomalies or communication failures in data communication between computers.

Even if a communication failure does not occur, periodic network maintenance is necessary to ensure that network line speeds are safe and normal. In this way, it is also effective for periodic network maintenance.

It is also used to verify communications during the development of network equipment or to check and verify communications when new communications equipment is installed or modified.

Thus, protocol analyzers are necessary to check and verify that the data transmitted and received over digital communication lines conform to communication protocols.

Principles of Protocol Analyzers

A protocol analyzer is a device or software that analyzes communication standards (communication protocols).
Basically, it is a device that monitors communication packets flowing through a data line. However, if it is a high-performance protocol analyzer, it can monitor data down to the bit level, and certain models also incorporate the functionality of a logic analyzer.

However, when analyzing the waveforms of signals flowing over digital communication lines, such as with an oscilloscope, it is necessary to select a special, high-performance model.

Today, there are a great many different types of communication protocols. We have not found any protocol analyzers that can handle all of them.

Therefore, as a choice of equipment, a model with general-purpose functions, such as a multi-protocol analyzer, can be used for all commonly used communication protocols, making it versatile.
Also, depending on the contents to be analyzed, the analysis time of a protocol analyzer is limited by the implemented memory. For this reason, selecting a model with sufficient memory for long-term analysis is necessary.

For simple analysis that monitors communication data, application-type protocol analyzers are available. Some of these products are available at low cost or free of charge.

Dedicated protocol analyzers are available for video and wireless protocol analysis. These protocol analyzers specialize in the corresponding protocol analysis and can even perform compliance testing, but they are costly.

What Is a Foot Switch?

A foot switch is a switch operated with the foot.

The foot action can be used to turn power or electrical signals on or off, or to switch electrical circuits. By operating switches with the feet, the work being done by hand can be continued without interruption, leading to improved work efficiency.

It may also be used to share the operation between the hands and feet. It is also useful in places where switches cannot be handled by hand for hygienic reasons (operating rooms in hospitals, and food processing plants).

Uses of Foot Switches

Foot switches are used in a variety of fields, including measuring instruments, medical equipment, amusement equipment including music players, nursing care and welfare equipment, industrial machineries such as machine tools and presses, and digital equipment input.

Typical functions are switches that are turned on and off by foot movement, but there are many different types of switches in terms of shape and function depending on the industry in which they are used and the specifications required. For example, in applications where signals are input as external input devices for digital equipment, specific keys on a keyboard may be assigned to footswitches using dedicated software.

The purpose of this is to improve the efficiency of input operations by sharing the input operations using the hands by performing certain key operations that are pressed frequently with footsteps.

Principle of Foot Switches

The typical construction of a foot switch is a microswitch built into an enclosure that supports a foot pedal. The microswitch is pressed by stepping on the pedal.

The pedal and housing are made of aluminum alloy or ABS resin. Since the pedal is stepped on with the foot, it must be strong.

There are also foot switches that do not use a pedal, but have a structure in which a foot presses a pushbutton switch large enough that the foot can be stepped on without error.

Types of Foot Switches

1. Momentary Type and Alternate Type

The momentary type and the alternate type are classified according to the difference in the change of the electrical connection state due to the stepping motion.

Momentary Type
As the name implies, it means “momentary. It operates by turning on only while the switch is stepped on.

Alternate Type
As the name implies, it means “alternating. When you step on the switch, it switches on and remains on even when you take your foot off.

Then, when you step on the switch again, it switches off and remains off when you take your foot off. Each time you step on the switch, it alternates between on and off.

2. Latch Type and Unlatch Type

There are type and unlatch-type footswitches with different mechanical actions.

Latch Type
When the switch is turned on by stepping on it, it is held in the depressed position. Then, when you step on it again, the switch returns to its original position and turns off.

Unlatch Type
The switch returns to its original position once you step on it, whether it is turned on or off.

How to Select Foot Switches

1. Conditions and Environment of Use

First, as an electrical component, it is necessary to confirm that the voltage (AC or DC) and current ratings to be operated conform to the conditions of use.

Also, select a type that matches the operating environment, such as a type with a dust-proof cover or a rain-proof type.

2. Shape

The pedal type is the most common, but there are also round types that can be stepped on from either side in 360°, which should be selected according to the application.

3. Method of Operation

Select the type of operation (momentary/alternating, latching/unlatching) that best suits the intended use. However, there are some applications where virtually only one way of operation exists.

For example, a pedal switch for music performance that controls the extension of the sound while playing an electronic piano. It is advisable to check that the pedal force required for the operation is not too large or too small and that the latch has an appropriate feel.

4. Polarity

Electric switches that switch the signal current have polarity (which side of the signal wire plug is + and which side is -), and it is necessary to check that the polarity is in the intended direction.

For example, footswitches for musical performance may have different polarity depending on the manufacturer of the instrument. If a footswitch with opposite polarity is used, the operation of the switch will be reversed.

What Is a Microphone?

A microphone is a device that converts sound into an electrical signal.

It is also commonly referred to as a microphone for short. By converting sound vibrations into electrical signals, microphones are mainly used for communication, recording, and voice amplification.

Whether digital or analog, microphones are generally referred to as audio input devices. While a microphone is an audio input device, a device that converts electrical signals into audio and outputs them is called a speaker.

Uses of Microphones

Microphones are used as audio input devices and are used in various forms for different purposes, such as broadcasting, music recording, and noise level meter measurements. They are also built into many electronic devices such as smartphones, PCs, IC recorders, and cameras for voice input and voice recognition.

They are also useful as loudspeakers for delivering voices to a large audience at concerts, live performances, lectures, and events. They are widely used in familiar places such as karaoke, sports events, and school events.

Principle of Microphones

Microphones convert acoustic vibrations into electrical signals, and there are various methods of this conversion. Specifically, there are dynamic types, condenser types, etc.

1. Dynamic Type

The dynamic type has a simple structure, with a coil attached to a diaphragm that converts sound into an electrical signal. The diaphragm called a diaphragm, voice coil, and magnet are used, and the magnetic flux is changed by the sound vibration and converted into an electrical signal.

The dynamic type is robust, easy to handle, and produces powerful sound, so it is often used for performances, live music, lectures, etc.

2. Capacitor Type

The capacitor type has a complex structure. The diaphragm serves as the electrode for the capacitor, which converts sound into an electrical signal. The diaphragm, which is charged with electricity, and the back plate, which is called the back plate, are combined to form an electrical capacitor. The distance between the diaphragm and the back plate changes the electric field in the capacitor due to changes in vibration. This change is used as the electrical input. It is characterized by higher sensitivity than the dynamic type.

Condenser microphones are more complex in construction, require internal electronic circuits, and are more expensive than dynamic microphones.

Types of Microphones 

1. Moving Coil Type

Moving coil-type microphones convert sound = air vibrations into electrical signals when a coil attached to a diaphragm, which is a diaphragm, moves in a magnetic field. This structure is similar to the magnetic pickup microphones used for guitars and basses, where the vibration of the strings generates an electrical signal.

2. Ribbon Type

A ribbon-type microphone uses a thin metal foil ribbon hanging between slits sandwiched by magnetic poles as a vibrating system, and the sound vibration generates an electrical signal at both ends of the ribbon. The lightweight structure of the vibrating system allows the microphone to pick up sound in a wide range of frequencies from high to low, and the frequency response is less peculiar and more natural sounding.

3. Carbon Microphone

Carbon microphones are microphones that utilize the change in contact resistance of carbon powder to obtain audio signals. It is constructed by placing carbon powder between two plate-shaped electrodes.

When a direct current is applied between the electrodes with one fixed electrode and the other movable electrode, the movable electrode vibrates due to voice, and the contact resistance between the electrode and the carbon powder changes to obtain a voice signal. Carbon microphones are robust and have very high sensitivity, but since they use the change in contact resistance of the carbon powder, they have the weakness of easily distorting the sound.

4. Piezoelectric Microphone

Piezoelectric microphones use piezoelectric elements to obtain sound signals by vibrating electrodes caused by voice. The sensitivity is high, but the output power is low.

They are mainly used in situations where bandwidth is limited. Wireless communication and concrete microphones are typical examples.

5. Laser Microphone

A laser microphone is a type of microphone that uses a laser beam to detect and demodulate light fluctuations caused by voice vibration using a light-receiving element. It is intended for use in environments and situations where conventional microphones are difficult to use, and several forms exist, including those based on the Doppler effect and interferometry.

Microphones called ion microphones or plasma microphones, which generate plasma without a diaphragm and apply sound waves to it to extract modulated sound waves, are also being studied.

What Is a Lithium Ion Battery?

A lithium-ion battery is a rechargeable battery that charges and discharges as lithium ions move between the positive and negative electrodes.

They are used in electric vehicles, industrial storage batteries, smartphones, and laptop computers. Compared to lead-acid batteries, the voltage is higher, and the ratio of active materials that can store energy in the battery is smaller, which has the advantage of making the battery smaller in size compared to batteries with the same amount of energy.

Batteries are products that deteriorate as they are repeatedly charged and discharged and eventually reach the end of their useful life. Lithium-ion batteries are no exception, but they have been confirmed to have a longer life than other batteries in an endurance test called a cycle test.

Applications of Lithium-Ion Batteries

Typical applications for lithium-ion batteries include IT, automotive, and energy.

Lithium-ion batteries have a high energy density, making it possible to produce small, thin, and high-capacity batteries. Applications such as cell phones and notebook PCs require smaller and lighter batteries, and lithium-ion batteries are widely used to meet these demands, with lithium-ion batteries being used in almost all products.

They are also used as a medium and large-sized batteries for electric vehicles (EVs) and energy storage systems, taking advantage of their high electric capacity.

Structure of a Lithium Ion Battery

A lithium-ion battery is similar to a typical storage battery, consisting of a cathode, an anode, and an electrolyte in which they are immersed.

The cathode and anode are separated by a membrane called a separator that allows lithium ions to pass through but not electrons, and the gap between them is filled with electrolytes. The lithium ions in the electrolyte move from the positive electrode to the negative electrode during charging, generating a potential difference (voltage) between the negative and positive electrodes, which can be connected to the desired circuit to generate a current (discharge).

In charging, lithium ions are transferred from the positive electrode active material to the negative electrode active material by applying an external voltage. After charging, lithium ions can move again in the direction of discharge, so the battery can be used repeatedly for charging and discharging.

Other Information on Lithium Ion Batteries

1. Electrode Materials

Cathode-active materials are mainly lithium-based oxides, such as lithium cobalt oxide (LCO). The type of cathode active material greatly affects the performance of lithium-ion batteries.

Carbon-based materials such as artificial graphite, natural graphite, and hard carbon are the main active materials for the negative electrode. Less commonly used materials include silicon (Si) and tin (Sn) alloys and lithium oxides such as titanium (Ti) and niobium (Nb).

2. Reaction Equation of Discharge in Lithium-Ion Battery

The reaction equation for discharge in a lithium-ion battery varies depending on the type of metal oxide and other factors, but an example is shown below. When charging, the reaction occurs in the opposite direction of when discharging, i.e., from the right side to the left side.

• Reaction on the cathode side: Li(1-x)MO2 + xLi^(+) + xe^(-) → LiMO2
  *M is a metallic element
• Reaction on the anode side: LixC → C + xLi^(+) + xe^(-)
• Reaction of the whole system: Li(1-x)MO2 + LixC → LiMO2 + C

3. Safety of Lithium-Ion Batteries

Abnormal Heat Generation in Lithium-Ion Batteries
The electrolyte used in lithium-ion batteries is a carbonate-based organic solvent that is highly flammable. Therefore, if a lithium-ion battery malfunctions and the temperature rises excessively, it may cause a fire or explosion.

Most abnormal heat generation is caused by a short circuit (short circuit) between electrodes. Short circuits between electrodes can be caused by various factors, such as strong external shocks and lithium metal precipitation (lithium dendrites) in the electrodes. Accidents involving the ignition of lithium-ion batteries can occur not only by mishandling but also during normal use.

How to Prevent Lithium-Ion Battery Ignition Accidents

The majority of lithium-ion battery-related ignition accidents are caused by misuse. Therefore, it is necessary to understand the proper handling of lithium-ion batteries in order to prevent ignition accidents. Specific precautions are as follows.

• Always use the charger specified by the manufacturer when charging.
• If you notice anything unusual during charging, stop using the battery immediately and consult the manufacturer or seller.
• If the lithium-ion battery swells or smells strange, stop using it and replace it with a new one. It is also essential not to disassemble or replace the lithium-ion battery forcibly, as it is difficult to replace it in some products and is not recommended.

It is also essential to select products with guaranteed safety. Products that have passed the safety standards set by the government are marked with the PSE mark, which indicates safety.

What Is a Rotary Coded Switch?

A rotary coded switch is an electric switch that can be switched by operating a lever or a button.

The main body has an operating shaft and a number of terminals to switch contact points.

Depending on the manufacturer, they are called by various names, such as rotary coded switches, rotary cord switches, and DIP cord switches.

The shape of the actuator of a rotary coded switch varies from flat to shaft-shaped. Some are small and require a screwdriver for switching operations.

Uses of Rotary Coded Switches

Rotary coded switches are often used to adjust the volume of audio equipment, but they are also used in a variety of other applications.

They are also used to set electrical values for microwave ovens, knobs on electric fans and other electronic devices, switch settings for pilots operating aircraft, switch settings for medical equipment, switch settings for construction and agricultural equipment, and stepwise control settings for AC/DC drives, among many other applications.

They are used in a variety of locations as switches that allow settings to be changed on human-operated inputs.

Principle of Rotary Coded Switches

A rotary coded switch has a step mechanism, COM contacts, contacts, etc., on the bottom of the rotary actuator and a number of terminals (contacts) around the bottom of the rotary coded switch.

As the actuator of the rotary coded switch rotates, the step mechanism moves the contacts at a predetermined angle, causing each contact to conduct with the COM contact.

Rotary coded switches are classified into two types, shorting type and non-shorting type, depending on the state of electrical connection between the contacts as they move during switching. The shorting type moves to the next switching point by shorting the two points when moving between the two contacts. Unlike the shorting type, the non-shorting type moves to the next switching point by opening once when moving between the two contacts.

When designing a circuit, care should be taken when selecting components since the design may vary depending on whether the two points are shorted or open.

What Is a Tube Fuse?

Tube fuses are safety devices used to protect electrical circuits by interrupting current flow when it exceeds safe levels. They contain a fusible metal wire within a glass or ceramic tube that melts (blows) under excessive current, thereby breaking the circuit.

Applications of Tube Fuses

Widely used in consumer electronics, automotive circuits, industrial machinery, and more, tube fuses safeguard against electrical faults. They are particularly valuable in systems where frequent current fluctuations occur, offering protection without the need for constant replacement.

Principle of Tube Fuses

The operation of tube fuses is based on the melting of a fuse element made from materials like lead, tin, or silver, whose composition determines the fuse’s melting point. This feature allows tube fuses to cater to a broad spectrum of rated currents, from low-power applications to those requiring currents of 30A or more.

Types of Tube Fuses

• Normal Fusing Type: Standard fuse for household electronics.
• Fast-Acting Fusing Type: Designed for quick response, suitable for semiconductor protection.
• Time Lag Fusing Type: Delays blowing for applications like motors, accommodating initial power surges.
• Glass Tube Fuse: Offers a visual indication of fuse status through a transparent glass body.
• Ceramic Tube Fuse: Provides higher breaking capacity and additional safety features like arc suppression.

How to Choose a Tube Fuse

Selection involves ensuring the fuse’s rated current exceeds the normal operational current of the circuit but responds appropriately under fault conditions. Factors such as material type, fusing speed, and application-specific requirements guide the choice of the appropriate tube fuse.

What Is a Surveillance Camera?

Surveillance cameras serve as electronic eyes, providing continuous monitoring in locations where constant human supervision is impractical. These cameras capture video footage for security and monitoring purposes, often utilizing digital storage to record events over time.

Applications of Surveillance Cameras

Surveillance cameras are essential across various settings, from retail stores and museums to power plants and control rooms in process factories. Their primary function is to enhance security, monitor operations, and ensure safety in both public and private spaces.

Principle of Surveillance Cameras

Modern surveillance systems comprise three main components: the camera itself, transmission wiring for signal relay, and a recording device for data storage. Transitioning from analog film to digital data storage has significantly improved efficiency, allowing for broader application and easier management of recorded footage.

How to Choose a Surveillance Camera

• Monitoring Range and Viewing Angle: Select based on the surveillance area, opting for wide-angle or zoom-capable cameras as needed.
• Resolution: Choose a resolution that meets your detail requirements, from 720p HD to 4K Ultra HD, depending on the need for clarity.
• Day/Night Capability: For 24/7 monitoring, ensure the camera performs well under varying lighting conditions, considering IR cameras for low-light environments.
• Security Features: Advanced features like motion detection and facial recognition enhance monitoring effectiveness and crime prevention.
• Reliability and Durability: Durability is critical for long-term operation, so look for cameras with environmental resistance and a solid warranty.
• Compatibility and Extensibility: Ensure the camera integrates well with existing systems and offers the flexibility to expand your surveillance network.