The testing equipments that are used for detecting faults in the operation of electronic devices by creating stimulus signals and capture responses from electronic devices under test (DUT) are known as electronic test equipments. If any faults are detected, then the identified faults can be traced and rectified by using electronic testing equipments. Most often all electrical and electronic circuits are tested and troubleshooted to detect faults or abnormal functioning if any.
Therefore, these testing equipments are necessary to find and analyze circuit conditions and maintenance in various industries. Many industries utilize different types of electronic test equipments ranging from the very simple and inexpensive to complex and sophisticated ones.
Types of Electronic Testing Equipments
The Basic Electronics Testing Equipments Under this Category Include the Following:
Voltmeter:
A voltmeter is a basic electronic device or instrument that is used for measuring voltage or electrical potential differences between two points in an electric circuit. There are two types of voltmeters: analog and digital. An analog voltmeter moves a pointer across a scale in proportional to the voltage of the electrical circuit. A digital voltmeter measures an unknown input voltage by converting the voltage to a digital value by using a converter and then displays the voltage in numeric form.
A voltmeter in a circuit diagram is represented by the letter V in a circle.
Ohmmeter:
An electrical instrument that measures electrical resistance is known as an ohmmeter. This instrument is used to measure small values of resistance are micro-ohmmeters. Similarly meg-ohmmeters is used to make large resistance measurements. Resistance values are measured in ohms (Ω). Originally, ohmmeter is designed with a small battery to apply a voltage to a resistance.
It uses a galvanometer to measure the electric current through the resistance. The scale of the galvanometer is marked in ohms (Ω), because the fixed voltage from the battery assures that the resistance decreases and the current through the meter increases.
Ammeter:
An Ampere meter called as an Ammeter is a measuring instrument used to measure the current in a circuit. Electric currents are measured in amperes (A). Instruments used to measure smaller currents, in the milliampere or microampere range, are designated as milliammeters or microammeters. Early ammeters were laboratory instruments which relied on the Earth’s magnetic field for operation. By the late 19th century, improved instruments were designed which could be mounted in any position and allowed accurate measurements in electric power systems. It is generally represented by the letter ‘A’ in a circuit.There are different types of ammeters such as moving-coil, moving magnet and moving-iron, etc.
Multimeter:
A multimeter also known as a VOM (volt-ohm-milliammeter), is an electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter can measure voltage, current, and resistance. Analog multimeters use a microammeter with a moving pointer to display readings. Digital multimeters (DMM, DVOM) have a numeric display, and may also show a graphical bar representing the measured value. Digital multimeters are now far more common due to their lower cost, greater precision having obsoleted analog multimeters.
A multimeter can be a hand-held device useful for basic fault finding and field service work, or a bench instrument which can measure to a very high degree of accuracy.
The Following are used for Testing Stimulus Signals of the Circuit Under Test:
Power Supplies:
A power supply is an electronic instrument that supplies electrical energy to an electric load. The primary function of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As a result, power supplies are sometimes referred to as electric power converters. Regulated power supplies refers to a power supply which supplies a variety of output voltages used for bench testing of electronic circuits, with the variation of output voltages or some preset voltages. Almost all the electronic circuits make use of a DC source of power for operation. A regulated power supply consists of various blocks such as an ordinary power supply and a voltage regulating device. The output generated from ordinary power supply is fed to the voltage regulating device that provides the final output. The main function of a power supply is to convert one form of electrical energy into another.
Signal Generator:
A signal generator also named as pitch generator, function generator or frequency generator is an electronic device used for generating electronic signals either in the analog or digital domains (repeating or non-repeating signals). Signal generators are used in testing, designing and repairing electronic devices.
In general no electronic device is suitable for all applications. There are various types of signal generators with different applications and purposes. During the development in technology, compared to signal generators there are flexible and programmable software tone generators with embedded hardware units are made available in the market.
Pulse Generator:
A pulse generator is either an electronic circuit or a piece of electronic test equipment used to generate electrical pulses in different shapes: mostly used for tests at analog or electrical level. Pulse generators are used to control the width, frequency,delay based on the low and high voltage levels of the pulses and with respect to an internal and external triggering. There are three types of pulse generators namely optical pulse generators, bench pulse generators and microwave pulsers.
The Following Equipments Analyze the Response of the Circuit Under Test:
Oscilloscope:
The oscilloscope is an electronic test instrument that constantly obverses varying voltage signals as a two dimensional plot of one or more signals as a function of time. The other names for oscilloscope are oscillograph, cathode ray oscilloscope or digital storage oscilloscope. It is also used for converting non electrical signals such as vibration or sound into voltages and then displays the result.
Oscilloscopes are used to observe the change of an electrical signal based on time such that voltage and time describe a shape of the signals and graphed continuously compared with a calibrated scale.The obtained waveforms can be considered for following properties such as frequency, amplitude, time interval, rise time and others. Modern digital instruments may calculate these properties directly and display them.
Frequency counter:
Digital frequency counter is an electrical test equipment used for measuring the frequency of repetitive signals and elapsed time between events. Digital frequency counters are also used to measure the radio frequency where it is important to measure the precise frequency of a particular signal.
There is a slight difference between the timers and frequency counters in the electronic industry. It is often possible to use both timers and frequency counters to perform the both functions: to measure the time and frequency. Frequency counters are mostly used as general purpose laboratory test equipment to measure higher frequencies.
Advanced or Less Commonly used Testing Equipment:
LCR Meter:
LCR Meter name itself indicates that it is used to measure the inductance, capacitance and resistance of electronics components. The inductance, capacitance and resistance are denoted by the letters L, C, and R so it is named as LCR Meter. A variety of meters are made available in the market, but simple versions of LCR meters indicate impedance only for converting the values to capacitance or inductance.
More designs are available and used to measure the capacitance or inductance, and also the equivalent series resistance of capacitors and the Q factor of inductive components. These conditions make the LCR meters valuable for measuring the quality and overall performance of the component.
