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What Is an Electronic Load?

An electronic load is a loading device that can provide a pseudo-resistance to a circuit. Conventionally, a load has been provided by incorporating a resistor.

However, this requires a huge resistor to apply a large load. Furthermore, to freely change the resistance value, another resistor with a different resistance must be reassembled.

The advantage of electronic loads is that the resistance can be changed arbitrarily. It is also possible to perform abrupt switching that cannot be done by hand. For this reason, electronic loads are also called resistive load devices.

Uses of Electronic Loads

Electronic loads are used to test the performance of batteries and power supplies. In addition to load performance tests of power supplies and charge/discharge tests of batteries, they are recently used to evaluate stack performance when fuel cells installed in fuel vehicles are connected in series.

Unlike the use of variable resistors to control load current, there is no need to manually move the sliding parts. Because computer-based control is possible, testing can be performed automatically while freely controlling the load current.

Types and Features of Electronic Loads

Setting an arbitrary resistance value using electronic loads is accomplished by using semiconductor elements instead of resistors as in the past. These semiconductor elements generate a pseudo-resistance by consuming or converting the input power as another form of energy.

Power Consumption/Conversion Method

There are two types of power consumption/conversion methods.

Thermal conversion type electronic load

The input power is converted into heat by semiconductor devices. This produces a voltage drop, which has the same effect as passing through a resistor. However, because of the heat generated, a heat removal system is required.

Power regenerative electronic load
The input power is converted into alternating current by an inverter. The converted current is returned to the power distribution network, so power consumption is small and there is no need to worry about exhaust heat.

However, since regenerated power energy is returned to the power grid, it is necessary to check in advance whether the environment is suitable for grid-connected operation.

Operation Mode

In electronic load devices, CC, CR, etc. indicate the operating mode of the electronic load. The following four modes of operation are available for electronic loads. During actual testing, use the correct mode with the correct setting value and test the device under test to avoid overloading the device under test.

Constant Current (CC) Mode

Operates to deliver a set current regardless of the input voltage, within the capability of the SUT (e.g., power supply) and electronic load. The electronic load adjusts the current flow so that it does not change even if the voltage of the device under test fluctuates. Therefore, in constant current (CC) mode, the load current is constant with respect to the input voltage.

Constant Resistance (CR) Mode

Within the capabilities of the device under test (e.g., power supply) and the electronic load, the electronic load maintains a constant set resistance value, like a fixed resistance. Passive loads are characterized by the fact that after a period of instability immediately after power-on, the balance between heat generation, resistance value, etc. is balanced and a certain resistance value is exhibited.

In constant resistance (CR) mode, the load current fluctuates proportionally to the input voltage, and is used for battery and battery capacity tests and start-up tests of electronic equipment.

Constant Voltage (CV) Mode

Within the capability of the device under test (e.g., power supply) and the electronic load, the electronic load works to maintain a set voltage. When the voltage drops, the resistance of the load is increased and the load is controlled in a direction to suppress the current.

In the low voltage (CV) mode, the load current fluctuates and the input voltage remains constant. Because the voltage is constant, the device is used for testing fuel cells, battery chargers, and other devices.

In battery charger testing, complex battery voltage behavior can be simulated with an electronic load.

Constant Power (CP) Mode

Within the capabilities of the device under test (e.g., power supply) and the electronic load, the electronic load works to draw power at a set power setting. First, the voltage of the device under test is measured, then the appropriate current is determined from the voltage and the set power value, and the current is drawn so that it flows.

How to Select an Electronic Load

An electronic load is an indispensable device in the development of power sources, such as power supplies and batteries, for testing them. Although it is possible to provide power with resistors, it is difficult to vary the load intentionally, and the heat generated makes it difficult to maintain stability, among many other inconveniences.

In such cases, programmable electronic loads can be used to create the load in the state required for the test. Since the state of the load is easy to control, it is possible to inspect the load from various angles. When selecting an electronic load device, the following points should be considered

Minimum Voltage at the Time of Measurement

The capacity of the electronic load device, but it is often not necessary up to the capacity of the power supply of the device under test. For example, when testing a 12V 50A power supply, it may seem that an electronic load of 600W or more is required because the capacity of the power supply is 600W, but in reality, it is often not intended to flow 50A at 12V.

For example, if 20A at 12V and 50A at 5V, then an electronic load of 240W or more would be sufficient.

Minimum Voltage that an Electronic Load Device Can Handle

Electronic loads are generally difficult to use at very small voltages. The minimum voltage that an electronic load device can handle is called the minimum operating voltage.

As can be seen in the maximum load curve of an electronic load device, the lower the voltage, the smaller the voltage, the smaller the current that can be drawn. In other words, when the voltage is low, there is a range in which the device is practically unusable.

Therefore, it should be noted that the equipment under test may not operate if the voltage is below this minimum operating voltage. When selecting an electronic load, it is important to check the minimum voltage at the time of measurement and the minimum voltage that the electronic load device can handle.

Ambient Temperature and Time

Some electronic loads have products that have a low ambient temperature at which the maximum load can be swept. Particular attention should be paid to resistive-consumption electronic loads, because the ambient temperature rises due to heat generation.

There may be a limit to the time that the maximum load can be maintained. Depending on the method of use, it may be necessary to check the catalog or spec sheet in advance.

What Is Resistance Welder?

Resistance Welder is a machine designed for welding metals.

The welding part is sandwiched between two electrodes, and pressure is applied to the metal while passing electrical current through it. Since Joule heat generated by the resistance of the metal to be welded is used, there are various types of welding machines, such as inverter, transistor, and capacitor types, depending on how the current is passed through the electrode. Welding machines are classified into direct spot, indirect spot, series spot, and twin spot, depending on the method of current flow.

Resistance Welders, due to their structure, are mainly used for welding flat objects such as metal plates and pipes. They can be used for a wide range of applications, such as body panels of automobiles and steel frames of buildings. Resistance Welders offer rapid and high-strength welding. However, Resistance Welders may not be suitable for certain materials.

For example, aluminum and stainless steel are difficult to weld efficiently due to their low resistance values. In addition, the heat generated during welding may cause distortion. Therefore, it is also important to note that accurate heating control is necessary.

Uses of Resistance Welders

Resistance Welders are mainly used in factory production lines where welding is required. For example, they are used to weld parts of automobile bodies and to join the chassis of home appliances. They are also used at construction sites to weld steel frames for construction.

Resistance Welders are characterized by their high welding speed and low consumable parts, making them ideal for automation in mass production. They are frequently used in mass production lines. In recent years, Resistance Welders that are compatible with automation have been developed, and are now in use in the manufacturing processes of automobiles and home appliances.

When selecting a Resistance Welder, it is necessary to consider cost factors such as electricity consumption, electricity and equipment costs, impact on other electrical equipment, the type and thickness of the metal to be welded, and welding quality. Resistance Welders must also be selected to suit the application, as the accuracy and speed of welding, as well as the range of welding that can be performed, vary depending on the installation method.

Principle of Resistance Welder

Resistance Welders consist of four elements: a power supply, a transformer, a pressure control device, and an electrode. The current supplied from the power source is converted to a high current by the transformer and flows to the electrode. The electrode is pressed against the metal by the pressure controller, and the current flowing through the metal generates Joule heat, enabling metal-to-metal welding.

There are three types of Resistance Welders: Single-Phase AC, Inverter, and Capacitor. The single-phase AC type is widely used for general purposes due to its simplicity and cost-effectiveness. The inverter type, on the other hand, uses an inverter to convert AC power into DC for welding, enabling high-quality welding and is used for welding aluminum and plated steel plates. The capacitor type stores electricity in a capacitor and releases it all at once, thus producing a large current. It is suitable for short-duration welding, but may not be ideal for continuous welding due to the time required for storing electricity.

Other Information on Resistance Welders

How to Use Resistance Welder

The metal to be welded is placed between the anode and cathode. Instantaneously, it undergoes intense heating and welding as a discharge of electricity occurs while pressure is applied between the electrodes. This discharge is typically initiated using a foot switch or push switch. The time of discharge needs to be adjusted in advance according to the type and thickness of the metal to be welded.

During test welding, the welding current and time are adjusted to the appropriate level for sufficient weld strength and to prevent excessive burning. Generally, copper and aluminum are difficult to weld with high current flow, so the current should be increased and the time should be set longer.

On the other hand, nichrome wire and steel plate are easy to weld due to their high resistance and can be welded in a short time.

What Is an Injection Molding Machine?

An injection molding machine is a machine that performs injection molding of plastic and other resins. The manufacturing process of injection molding begins by pouring heated, softened resin into a mold. The mold is then subjected to high pressure, and the cooled product is removed.

Injection molding is the most commonly used method of molding plastics and other resins. Many familiar products, such as stationery and cell phone parts, as well as automotive and home appliance parts, are produced by injection molding.

Uses of Injection Molding Machines

Injection molding machines are used to produce many household items. This is because injection molding machines specialize in the molding of resins. Injection molding machines can mold a wide range of resin materials, including thermosets, thermoplastics, and elastomers.

Products manufactured by injection molding machines include automotive interior and exterior parts. Most automotive interior and exterior parts are molded on injection molding machines. In addition, most exteriors of everyday products such as electric fans, microwave ovens, televisions, and washing machines are also produced by injection molding machines.

Injection molding machines are indispensable in the manufacture of familiar products, from small parts to large products.

Structure of Injection Molding Machines

The structure of an injection molding machine is divided into an “injection section,” which injects resin, and a “mold clamping section”, which molds the product. In the injection section, the resin is melted at a high temperature of approximately 200°C and poured into the mold. The flow is automated by simply setting the amount and temperature to be poured into the machine.

The mold is installed in the mold clamping section. The mold must be moistened with a mold release agent and warmed up to prevent resin from sticking to it. Resin is poured into the mold from the injection section, and the mold is clamped under high pressure for molding.

After molding, the resin is cooled to completion. The removed resin has burrs, which are removed and inspected before it is made into a product.

Types of Injection Molding Machines

Injection molding machine types are classified according to the materials to be molded and the structure of the injection molding machines. There are two main types of materials used by injection molding machines: thermoplastics and thermosetting plastics. 

• Thermoplastics deform when heat is applied.
• Thermosetting plastics harden when heat is applied.

The most common injection molding machines are for thermoplastics. There are also three types of injection equipment: plunger type, pre-plunger type, and screw type.

• Plunger Type
  Material is injected using a piston-type plunger. This method was common until the 1960s but is now used only for special applications.
• Pre-Plunger Type
  This method combines two cylinders. Since two cylinders are used, a high cycle time is possible.
• Screw Type
  A single screw is used to measure and inject material. Also called the screw-in-line method, this is the most common method used today.

In selecting an injection molding machine, it is necessary to have a good understanding of the type of material and structure used. This is because if the combination is not right, there is a possibility that the product will not be molded well.

In addition, care must be taken because failure to mold the product will further result in huge costs.

Other Information on Injection Molding Machines

Advantages and Disadvantages of Injection Molding Machines

The advantage of injection molding machines is their extremely high production efficiency. When manufacturing small parts, injection molding machines are designed to produce as many products as possible with a single mold to achieve high production efficiency.

Injection molding methods are simple, and injection molding machines are highly automated. The major advantage of injection molding machines is their extremely high productivity.

The disadvantage of injection molding machines is that they are costly. Injection molding machines must be strong enough to withstand the high pressure of the injection section. In addition, the mold clamping section requires the production of high-precision molds.

To meet the requirements of high strength of the injection section and high precision of the mold, development and processing costs are incurred. Since individual molds are manufactured for each desired product, a large initial cost is required.

What Is an Isolated Gate Driver?

An isolated gate driver is a circuit used to drive and control the gate terminals of a voltage-driven type of MOSFET or IGBT.

Currently, the most general-purpose isolated gate driver is a circuit that drives and controls the gate of a MOSFET, but there are analog circuit technologies that use resistors, diodes, bipolar, and other transistors. Recently, isolated gate driver peripheral circuit components themselves have also evolved.

Although there are many types and combinations of them, learning gate voltage drive control circuits using MOSFETs is the most practical.

Uses of Isolated Gate Drivers

Isolated gate drivers are used to drive power transistors with a simple drive circuit consisting only of MOSFETs and gate resistors.

The advantage of isolated gate drivers is the small number of components. The disadvantage is that switching speed and loss vary greatly depending on the resistance value, and it is difficult to set an appropriate resistance value. As a circuit that improves this problem of adjusting the resistance value, it is also used in circuits where the gate of a MOSFET is turned on and off separately driven by a diode.

The voltage for the diode remains, so it cannot be completely zero, but a circuit called a push-pull, in which the Pch and Nch of the MOSFET are connected up and down solves this problem. This is currently the most common use of isolated gate drivers.

Principle of Isolated Gate Drivers

Isolated gate drivers consist of a push-pull circuit of transistors.

A push-pull circuit is a circuit that performs switching or amplification by using two transistors to operate alternately. There are two types of push-pull circuits: “emitter follower type” and “emitter grounded type,” but the latter is used in most cases.

The isolated gate drivers consist of a circuit that acts as a middleman between the power element, which is the powerhouse that does the heavy lifting at the transistor site, and the microcontroller, which is the brain that commands the control policy and plays the role of president.

Power MOSFETs and IGBTs are examples of power elements that can carry large currents. The voltages and currents that directly drive these devices are in most cases insufficient for the currents and voltages that a normal microcontroller can output.

Therefore, isolated gate drivers are needed between the power devices and the microcontroller to drive them.

Other Information on Isolated Gate Drivers

1. Ultra-High-Speed Isolated Gate Drivers

Ultra-high-speed isolated gate drivers are isolated gate drivers that specialize in high-speed switching. The ultrahigh-speed category is generally defined as a device with a switching speed of several tens of ps (pico-seconds) or less.

Pico is 10 to the minus 12th power, so the switching speed is less than one trillionth of a second. This evolution can be said to have occurred due to recent technological innovations in semiconductor devices. 

2. Practical Application of Ultra High-Speed Gate Drivers

The following ultra-fast device isolated gate drivers are in practical use.

The first is a transistor using silicon, the most commonly used semiconductor. The bipolar type is fast, and capable of switching in tens of picoseconds, while the MOS type has delayed operation but is suitable for high-density circuit integration.

The second type is the compound semiconductor type transistor. These include the MESFET, a Schottky gate-type field-effect transistor, the HBT, a hetero-bipolar transistor, and the HEMT, a high-mobility field-effect transistor. The semiconductor used is a gallium arsenide compound. This device is capable of switching operations of a few picoseconds, making it the fastest semiconductor available today for ultrahigh speeds.

The third, although still in the research stage, is the Josephson device, which utilizes the tunneling effect between two types of superconductors; it has half the switching speed of the second device and uses metallic materials such as niobium. However, it requires cryogenic temperatures for operation, and there are still challenges to be overcome before it can be put into practical use.

3. SiC Isolated Gate Drivers

SiC isolated gate drivers are semiconductor devices that have been attracting attention in the recent power electronics world because of their superior breakdown voltage performance and improved switching speed. The isolated gate drivers are composed of a semiconductor called silicon carbide (commonly known as SiC), the use of which has become a trend in the industry.

In particular, MOSFETs using SiC have contributed to a significant improvement in switching performance, which has been an issue in high-power inverters and have improved heat dissipation while achieving high breakdown field strength and carrier drift speed.

However, SiC has the challenge of resolving voltage differences in various SiC composition configurations.

4. Current Mainstay Devices in Isolated Gate Drivers

Currently, the main devices that we want to operate with isolated gate drivers are voltage-driven devices called MOSFETs and IGBTs. Although isolated gate drivers do not require a constant flow of current, they do require a short pulse current during switching operations, so the rated current and voltage values as power devices must be carefully considered.

In particular, in the case of IGBTs, compared to MOSFETs, their characteristics are best demonstrated at high voltages of several 10 V. Therefore, it is safer to select bias characteristics for the isolated gate drivers that match the voltage range and application as much as possible.

5. Modularization and Future Trends

IGBTs are characterized by their tendency to operate at high voltages and to break down instantly when their maximum ratings are exceeded. For this reason, IGBT modules, which combine IGBTs with isolated gate drivers ICs and protection circuits, are easier to use than IGBTs alone (discrete) and are now widely accepted in the market.

Future trends in isolated gate drivers technology development will include not only more compact, high-performance, and easy-to-use products but also application-specific ICs such as Class-D amplifiers and motor drive ICs. These isolated gate drivers will be differentiated from the isolated gate drivers for SiC semiconductors and GaN devices mentioned earlier.

What Is a Brush Motor?

A brush motor is a motor with sliding contacts called brushes to conduct current to the rotating shaft. They are characterized by simple and inexpensive construction and easy torque control. However, brushes are worn by rotation and require periodic maintenance. The disadvantage of brush motors is that they are noisy when driven.

Although wound AC motors and other types of motors also use brushes, the term “brush motor” generally refers to DC brush motor.

Uses of Brush Motors

Brush motors are used in a wide range of applications, from consumer products to industrial applications. Typical examples are as follows

• Small office fans and PC cooling fans
• Industrial equipment such as boiler exhaust fans
• Running motors for commuter trains
• Elevator lifting motors

Because they are inexpensive among DC motors, they are used in cooling fans for DC office equipment. They have also long been used in moving equipment such as trains and elevators because of their easy torque and rotation speed control.

In recent years, inverter control, which requires no brushes and is easy to maintain, has become the mainstream for torque control in mobile equipment. Brushless motors are also becoming popular.

Principle of Brush Motors

Brush motors consist of a rotor, stator, and commutator. The stator may use a coil or a permanent magnet.  

The stator generates a magnetic field at all times, and the current flowing in the coil wound around the rotor, and the stator’s magnetic field generates electromagnetic force to rotate the motor. It is important that the brushes are in contact with the commutator and that the direction of the coil current is in one direction.

Torque and speed can be controlled by changing the magnitude of the current.

Other Information on Brush Motors

1. Brush Motors Life

The brush life of brush motors is generally several hundred to several thousand hours. On the other hand, the life of the brush motors itself is determined by the life of the bearings and is generally tens of thousands to hundreds of thousands of hours.

Brush motors rotate by switching between repelling and attracting forces between the stator and rotor. For the rotor to rotate, the polarity of the magnetic force must be switched according to the angle of rotation, and the commutator plays this role.

While the drive is simple and easy to use by simply applying DC voltage, the brushes are mechanical contacts that wear out due to rotation, so if the brushes cannot be replaced, the life of the motor depends on the life of the brushes.

2. Difference from Brushless Motors

Brush motors are also called DC motors because they can be easily driven by a DC power supply. Brushless motors, on the other hand, are also called permanent magnet synchronous motors. Brush motors are easier to drive and less expensive than brushless motors, making them suitable for a wide range of applications.

Brush motors are used in many applications, but their short life span due to brush wear is a drawback. Brush replacement is necessary for long-term use. Brush motors can be controlled not only by DC voltage but also by PWM pulses.

Brushless motors, on the other hand, eliminate the commutator and brushes and use permanent magnets in the rotor. The absence of brushes gives brushless motors a longer life, and bearing life is the life of a brushless motor.

The brushless motor drive is classified into “square wave drive” (a method of driving with square wave voltage) and “sine wave drive” (driving with sine wave voltage). While square wave drive has a relatively simple drive circuit, it generates noise and vibration during rotation. Sine wave drive, on the other hand, has a more complex drive circuit but features lower noise and vibration during rotation.

What Is a Slide Potentiometer?

A slide potentiometer is a type of variable resistor with a knob that slides horizontally to move the contactor.

It is one of the variable resistors whose resistance value is changed by physically moving the contactor. Variable resistors also include rotary types called rotary volumes and potentiometers. The main difference is that the slide potentiometer moves horizontally in one direction, whereas these move the contactor in the rotational direction.

Slide potentiometers can also be structurally designed to handle more power than rotary ones.

Uses of Slide Potentiometers

Typical applications for slide potentiometers include audio mixers and graphic equalizers in PA (public address) equipment, and dimmers to control room lighting. Whether a slide potentiometer or a rotary type, the function as a variable resistor is the same, but the appearance and the user’s sense of operation are very different.

Therefore, they are selected according to the usage and outfit (design) envisioned when developing devices and products. In particular, by adding a memory next to the slide pick, the amount of setting can be visually grasped, so it is often utilized for applications such as adjusting volume or light intensity.

Principle of Slide Potentiometers

When the position of the slide potentiometer pick is moved, the resistance value between the terminal connected to one end of the resistive element and the terminal connected to the conductor connected by the contactor changes according to the distance from the end of the resistive element to the contactor. This allows the resistance value to be changed according to the position of the plucking.

Structure of Slide Potentiometers

A slide potentiometer has a resistive element of a certain length, covered by a body case, with terminals at both ends of the resistive element for connection. There is a slit in the body case where a plucking tool can slide, and a plucking tool with a contactor attached is placed there.

In parallel with the resistive element, there is a conductor in the case, and the contactor is in contact with both the resistive element and the conductor. The conductor is also equipped with terminals, and together with the terminals on both ends of the resistor, it has a structure with three terminals.

Other Information on Slide Potentiometers 

1. Characteristics of Slide Potentiometer

A slide potentiometer changes its resistance according to the position of the pick, and the degree of change in resistance relative to that distance can be expressed as one of the three curves shown in ABC. When a voltage is applied to both ends of the resistive element and the position of the contactor is varied, a voltage appears between the terminal on one side of the resistive element and the terminal connected to the conductor connected by the contactor.

• In the Case of Curve A
  The above voltage varies logarithmically with the distance of the pick.
• In the Case of  Curve B
  The above voltage varies proportionally to the distance of the pick.
• In the Case of Curve C
  The above voltage varies inversely logarithmically with the distance of the pick.

Therefore, it is important to decide in advance at the design stage which characteristic to use. 

2. Resistance of Slide Potentiometer

Among slide potentiometers, those used for small signals often have carbon or metal film resistive elements and are not suitable for high power applications. Rotating resistors, in particular, are structurally disadvantageous for using large resistive elements because the length of the resistive element is limited by its diameter.

Slide potentiometers, however, are less restricted in terms of resistive element length. Some product groups use enameled resistors for resistive elements or wire-wound resistors with resistive wires wound on rods, and these are available in power ratings from tens to hundreds of watts.

What Is a Laser Marker?

A laser marker is a device that marks or processes objects by irradiating them with a laser beam. This technology allows for high-precision printing and produces marks that are more resistant to fading than those made by inkjet printers and other printing methods. Laser markers can print on a variety of materials, including metals, resins, glass, and wood.

Uses of Laser Markers

Laser markers are employed across various industries, such as automotive, food, and semiconductor fields, for tasks like:

• Printing 2D codes for tracking the manufacturing history of automotive parts
• Applying lot numbers on electronic components
• Marking serial numbers and expiration dates on beverage cans
• Microfabrication of metal parts

With their capability for precision processing, laser markers are increasingly preferred over traditional engraving methods like drilling.

Principle of Laser Markers

Laser markers operate primarily through two methods: masking and scanning.

Masking Laser Marker

This method involves irradiating a laser beam through a patterned mask to print. While it allows for detailed marking, it requires a unique mask for each pattern, making it time-consuming and costly.

Scanning Laser Marker

Here, a laser beam is scanned over the material according to the desired pattern using a galvanometer mirror. This technique allows for precise control and is adaptable for curved surfaces. The scanning method is widely used due to its efficiency and flexibility.

Types of Laser Markers

The choice of laser for a marker depends on the material and the specific processing requirements. Common types include:

YAG Laser

Utilizing YAG crystal, these lasers are versatile, suitable for marking on aluminum cans and plastic surfaces without damaging the materials.

Fiber Lasers

Fiber lasers, using optical fiber as the medium, provide high output power for deep marking into metals.

CO2 Laser

CO2 lasers, ideal for processing transparent materials, are commonly used for marking and processing glass.

Other Information on Laser Markers

Laser Markers for Home Use

Home-use laser markers are available for personal projects, like engraving names on wood or resin plates, and include safety covers to prevent dust scattering and accidental laser exposure.

Handheld Laser Markers

Compact laser markers, similar in size to a digital camera, offer portability for on-the-go marking, though they require a stable platform like a tripod for precise work.

Price of Laser Markers

Prices range widely from affordable options for hobbyists, costing about 50,000 yen, to industrial models priced between 1,000,000 yen and 5,000,000 yen, with high-power versions for metal processing reaching around 10,000,000 yen.

What Are Check Terminals?

Check terminals are terminal components processed to facilitate temporary wiring connections.

They are used for checking the operation of electronic components in circuit design or to check electrical characteristics in manufacturing processes. Probe-type terminals are commonly used for measuring instruments, such as oscilloscopes.

Since it is difficult to always hold a probe in one’s hand while conducting inspections, measurements are made by connecting it to a check terminal. Check terminals are also available in many shapes that are easy to apply probes to, reducing errors caused by human restraint.

They are sometimes referred to as checker chips or test terminals. In recent years, many RoHS-compliant products have also been sold.

Uses of Check Terminals

Check terminals are used to check board operation and electrical characteristics. The following is an example of where check terminals are used.

• Mounting on evaluation boards
• Signal extraction from logic circuits

Check terminals are used as a mounting base for direct connection to the board and are often mounted on the finished product.

Principle of Check Terminals

Check terminals are components that are placed in a circuit to expand the conduction area and facilitate measurement. Stainless steel or brass is used as the material, and the outside is plated with gold or brass over nickel. Operating temperatures range from -40°C to 150°C.

In many cases, colored beads are attached so that the color of the beads can be distinguished. The beads are made of glass or resin.

Types of Check Terminals

There is a wide range of types of check terminals, depending on the application. Shapes include the type that the probe is pressed against, the type that is hooked onto a loop, and the type that is fastened with an alligator clip.

Check terminals for logic circuits, which are suitable for logic circuits, can be attached to through-hole lands for top and bottom continuity. Check terminals for panels and signal checks are also available.

How to Select Check Terminals

Check terminals are sold by manufacturers specializing in peripheral accessories required when checking board operation, such as Mac-Eight. Check terminals are available for board mounting or surface mounting, and it is important to select the right one for your application.

Also, since there is a wide lineup of sizes and shapes, check terminals are selected according to the board space and the shape of the probe. Products that are not plated on the inside can be used for flow soldering, and the color of the beads can be differentiated for each signal line.

Other Information on Check Terminals

1. Check Terminal Blocks

Check Terminal Blocks are products with check terminals on the board as terminal blocks. Common parts, such as ground terminals and power supply terminals, are replaced with short bars, thus saving space and cost.

If check terminal blocks are not used, it takes time and effort to arrange multiple check terminals in a row, etc. Multiple tester terminals and alligator clips must also be used. By using check terminal blocks, work during inspections such as continuity and withstand voltage tests can be reduced.

Time can also be saved by using check terminal blocks during breakdowns and maintenance. It drastically reduces labour-hours spent on fabrication of electrical inspection jigs and inspection work.

2. How to Use a Check Terminal

Use a check terminal at the point where you want to check the voltage, etc., with a tester or oscilloscope. The check terminal should be soldered directly to the circuit, and a probe can be used to measure the voltage directly.

Generally, the check terminals are installed in the shortest distance from the point where you want to measure and in a position where they will not be affected by other circuits. Decide on the location of the check terminal at the time of circuit design. It is a good idea to avoid placing tall electronic components around check terminals, taking into account that probes may be applied to them.

Incorrect selection or placement of check terminals may have adverse effects such as increased wiring capacitance and influence of wiring impedance due to increased wiring length and wiring area. Reflected noise due to unnecessary radiation noise, etc., can result in erroneous measurements due to so-called wiring impedance matching or unbalanced shielding lines.

What Is an Arbitrary Waveform Generator?

An arbitrary waveform generator is a signal generator that can generate signals with arbitrary frequencies and waveforms.

Function generators of the past could only output signals with a fixed pattern.

In contrast, waveform generators have increased functionality and are characterized by the ability to generate arbitrary signals that can be set by the user, even when complex waveforms are required. The most common method of generating arbitrary waveforms is to store digital waveforms in semiconductor memory and output them by D/A conversion.

Uses of Waveform Generators

Waveform generators are often used in the development and testing of electronic equipment. Systems and individual components are repeatedly tested using waveform generators for design, testing, and manufacturing.

For example, they are used in wireless communication applications involving intermediate frequency (IF) and radio frequency (RF) signals, as well as testing in physics fields such as quantum computing and spintronics.

Some waveform generators can generate waveforms at high speed, while others allow the user to freely define and output sequence, modulated, or pulse waveforms.

Principle of Waveform Generators

The most mainstream waveform generator used in the past was called a function generator (FG). In addition to sine and pulse waves, these waveform generators can also generate triangle, ramp, and noise waves. Although function generators can also generate simple arbitrary waveforms, they cannot sufficiently generate complex waveforms.

Waveform generators generally consist of a large waveform memory, a clock signal source, and a D/A converter. This allows the sample frequency in the clock signal source to be set arbitrarily so that all waveform data recorded in the waveform scale can be output without interruption.

Specifically, by replacing the waveform ROM portion with rewritable RAM in the digital direct synthesizer DDS method oscillator, the user can freely write waveforms. The DDS method consists of an accumulator with an adder and a latch, and accumulates the frequency setting value N in synchronization with the clock to obtain digital data in the form of sawtooth waveforms.

Other Information on Waveform Generators

1. Functions of Waveform Generators

Arbitrary waveforms include sine, square, triangular, and sawtooth waveforms, as well as waveforms with a time component such as continuous, single-shot, and intermittent waves.

Frequency is not only constant, but also has a function called sweep, which continuously changes the frequency. In addition, the amplitude can be generated arbitrarily from 10 mVp-p to 30 Vp-p.

2. How to Use Waveform Generators

Waveform generators have multiple output terminals, which are BNC terminals, making them resistant to noise and minimizing signal transmission loss.

The output impedance is 50 Ω, so care must be taken to attenuate the signal if the input impedance of the circuit to which it is connected is low. Each output terminal can output waveforms as desired.

They are also used for driving signals for various test equipment, such as changing the rotation speed of a motor or arbitrarily changing the vibration frequency of a vibration tester.

3. Waveform Generators With USB Connections

Recently, an increasing number of arbitrary waveform generators have USB ports. Waveform generators can be controlled via USB by setting arbitrary waveforms with a PC application.

USB is also used as a communication port for ON/OFF or frequency sweep by an automatic control program. Extensive control is possible, such as switching between sine, square, sawtooth, and burst waveforms, changing amplitude and duty, and frequency sweeping.

What Is a Drop Tester?

A drop tester is a device that allows a test object to be dropped spontaneously while repeatedly maintaining a specified height and other conditions in order to determine the impact and effects of dropping the object.

In particular, easily portable and compact smartphones and mobile devices require countermeasures against the impact caused by drops in their operating environment. In order to improve the shock resistance of equipment due to drops, which are relatively easy to occur in the operating environment, it is very important to conduct highly reproducible drop tests.

Drop testers are also used to test the impact resistance of heavy cargo and packaging materials.

Uses of Drop Testers

Drop testers are used in the development of a wide variety of products. The main application is for industrial products. Drop tests are conducted under two main conditions: one assuming the logistics process and the other assuming the product’s usage environment.

1. Drop Test Assuming Logistics Process

Drop tests are mainly used for the development of products that are to be placed in a specific location. Examples are large home appliances such as televisions and refrigerators. These products are very unlikely to be dropped in our daily lives.

Large home appliances may accidentally fall during shipping, distribution, and transfer to stores or purchaser’s installation location. 

2. Drop Test Assuming the Product’s Usage Environment

Products that may be dropped depending on the environment in which they are used include mobile devices. Small electronic devices such as smartphones and digital cameras are carried around and used, so it is not uncommon for them to experience drops. Drop test are used to verify the durability and reliability of products subjected to such drops.

Principle of Drop Tester

The principle of drop tester can be divided into the following types: Holding-Fall Type, Rotating Drum Type, Rotating Arm Type, and Electromagnetic Hook Type.

1. Holding-Fall Type

The holding-fall type has a simple structure. The object is clamped and secured horizontally using a pneumatic pen cylinder. When the object is dropped naturally from a set height, the cylinder separates from the object in the middle of the fall, allowing only the object to fall. This method is effective when you want to drop the object at the same angle.

2. Rotating Drum Type

In the rotating drum type, the object is placed in the drum and the drum rotates at a constant speed. The object can be repeatedly dropped in the drum at random.

3. Rotating Arm Type

The rotating arm type has a drop test mechanism using an air-driven cylinder and a spring. After the table on which the object is placed is moved at high speed by the air cylinder, the table is rotated by the tension of a strong spring and the object is dropped vertically in a natural manner.

4. Electromagnetic Hook Type

The electromagnetic hook type is a device in which cargo suspended by electromagnetic hooks falls naturally when the hooks are released.

In either case, the height at which the cargo is dropped can be set freely. In addition, the drop operation can be set either by remote control or by a control panel. In addition, some of them are equipped with a high-speed camera and can analyze the state of falling.

Other Information on Drop Testers

Drop Test Applications

In drop impact testing, tests are conducted assuming a situation in which a fall actually occurs. If the product to be used is a medium or large-sized household appliance, it is assumed to be used in a stationary position, but for a cell phone, it is desirable to test for a drop from a position half the height of the user.

If the product is expected to be used in a stationary position, a drop test from the height of a truck when loading cargo is conducted to examine the possibility of dropping the product during the distribution process. In addition, the test should not be limited to simple height, but should also include loading by hand, using a forklift, or using a crane to hang the truck if the load is too heavy to be loaded under special conditions.

For example, it is necessary to drop the load while turning. For example, a cell phone can be assumed to be accelerated, not just dropped, so an impact test is also conducted to physically apply velocity to the object.