How to Pick a Power Supply for the Test Bench
Power is an essential ingredient for testing any active device under test (DUT), although electronic DUTs vary widely as do their power-supply requirements. Finding the right power supply for the laboratory or the production line starts with a budget and it ends hopefully; with finding a power source that meets all the test needs for present and future DUTs. Whether it is an AC power source or a DC power supply, or a single unit that can provide both types of power, a practical power supply will provide controlled current and voltage to enable testing a DUT under all the different operating conditions it is likely to see in actual use.
Performance requirements for a power supply start with the DUT. For example, a DUT may be a ...
Amplifiers are widely used in electronic circuits and systems. They raise signal amplitudes as needed, whether to drive low-impedance audio amplifiers or higher-impedance RF/microwave circuits. They are characterized by various sets of measurements, with some for audio amplifiers and some for higher-frequency amplifiers. Evaluating the performance of an amplifier calls for the right tools, and finding the right test equipment is a matter of understanding which measurements must be performed.
Amplifier measurements differ by frequency, with some measurements for audio amplifiers, and different measurements for higher-frequency amplifiers. Audio amplifiers, which are typically specified from 20 Hz to 20 kHz, are typically tested from at least 20 Hz to 50 kHz to account for any harmo...
Amplifiers are often needed as part of an RF/microwave test setup, to boost test signal power. Commercial test signal generators may provide +10 dBm or less output power, especially at the upper-frequency portion of their bandwidth. This is not nearly enough power to characterize passive components, such as attenuators and filters, under realistic conditions or stress them under maximum power conditions. It is also not enough test input power to drive many active components, such as amplifiers, to their compression points, such as 1-dB compression or 3-dB compression. For that reason, when testing an amplifier, often an additional amplifier is needed to add gain to the test signals. The choice of test amplifier will be determined by the bandwidth and power requirements of a particular test...
Batteries provide the power for portability, from the miniature rechargeable batteries of cellular phones to the larger battery packs of electric vehicles (EVs) and hybrid electric vehicles (HEVs). Ideally, rechargeable/regenerative batteries provide long operating lifetimes; with long discharge cycles and short recharge times. To determine performance levels, rechargeable secondary batteries must be tested for a number of meaningful parameters with the appropriate measurement equipment. Testing can tell such details as how well a battery can hold its charge in terms of voltage, current, and power, how efficient it is, and how effectively it can be recharged.
Rechargeable batteries of different chemistries, such as lead-acid, nickel-cadmium (Ni-Cd), and lithium-ion (Li-ion) types, are use...
Clean energy is vital to an evolving world and its increasing use of electronic devices, and a distributed power grid provides the means to provide that power. In a distributed power grid, the energy comes from many different sources and technologies, including solar power inverters, hydroelectric power, and wind power generators. Distributed energy resources (DERs) that are sometimes part of a power grid are switched on and off as needed according to user requirements. Efficient management of a distributed power grid requires such capabilities as remote control of the microgrids or different portions of the grid, so that they can be switched in and out as power is needed and, especially, regular measurement and maintenance of the performance of the different parts of a distributed grid.
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Phase noise describes a signal source’s short-term variations in frequency or phase as a function of time. That is how it is known in the frequency domain; it is also known as clock jitter in the time domain. A signal source, such as an oscillator or frequency synthesizer, without phase noise, would be capable of generating pure sine waves that would never vary from a tuned frequency: all of the source’s energy would be concentrated in the carrier frequency, with no frequency deviations to cause lower and upper noise sidebands at frequencies below and above the carrier, respectively.
However, real-world signal sources suffer short-term variations in frequency and phase noise. The amount of phase noise is a barometer for the amount of frequency stability possible from a...
Measurements of DC power can reveal a great deal about a system or its components. Power consumption is a global concern, and DC measurements, depending upon the choice of test equipment, can provide important details about the components that handle DC power within an electronic system, such as AC-to-DC converters, DC-to-DC converters, DC to AC converter, DC loads, inverters, and power supplies. The levels of DC power that often must be measured can range from milliwatts in portable electronic devices to thousands of watts produced by DC power generators and power supplies. While it is possible to determine power by measuring DC current and voltage with a voltmeter, modern test tools can make the task much easier by automatically measuring DC current and voltage over multiple channels and...
One of the more recent developments in power electronics are wide bandgap (WBG) semiconductor devices. According to the U.S. Department of Energy, WBG semiconductor devices will:
Operate up to 300 degrees C
Operate at voltage up to ten times the operating voltage of conventional semiconductors
Eliminate up to 90% of the power losses in electricity transfer compared to current semiconductor technology
They also switch faster and have a higher frequency response than current semiconductor devices.
WBG semiconductor devices are made from silicon carbide (SiC) and gallium nitride (GaN) semiconductors. You can currently purchase SiC MOSFETS, BJTs, and Schottky diodes and GaN FETs and Schottky diodes. Applications for these devices include electric vehicles, power conversion for wind an...
What is EMC/EMI?
The letters EMC stand for electro-magnetic compatibility and likewise EMI stands for electro-magnetic interference. There are standards that are used to determine whether or not a test article is susceptible to, or emits, an unacceptable level of interference. It can be either radiated or conducted in form. The standards are defined by regulatory agencies worldwide and are specific to particular scenarios. There are literally hundreds of different standards that various types of equipment must meet depending on their application and country of origin.
Electronic devices cannot be sold unless they pass the standards specified for the type of device it is, and the location or environment it is being used in. This is a safety and compatibility requirement. This makes testin...
What Is An Environmental Chamber?
An environmental chamber is used to test various types of equipment under controlled environmental conditions. These conditions include temperature, the most common variable, and sometimes, humidity. More advanced types can run programs to cycle the variables over extensive ranges and are used to validate the performance of various types of equipment when subjected to extremes of temperature, and humidity. Also needing to be considered is the number and type of connections available for connecting to the unit under test. Power, temperature probes, thermocouples, and communication busses are passed through ports that can be on either side, both sides, and even the front door. Some specialized types of chambers are used for EMI testing and will not be cover...
What Is An RF Amplifier?
An RF amplifier is similar to an audio amplifier, but applied at much higher frequencies. The frequency boundary where an amplifier is considered to be an RF type is typically vague. Applications requiring a frequency over 100 kHz often defines this boundary. We will address this in the amplifier types and frequency response section. Being an amplifier we will be concerned with power output, or wattage, frequency response, noise figure, efficiency, gain, and distortion / linearity.
Amplifier technologies come in several types. Each type will have a different frequency response characteristic. The major technologies of RF power amps include: vacuum tube, TWT, and solid state. The solid-state types can be further classified as bipolar junction o...
The Spectrum Analyzer
The spectrum analyzer, also referred to as a “spec an”, is an essential piece of test equipment for the engineer’s bench. The spectrum analyzer displays frequency vs. amplitude as opposed to time vs. amplitude as with an oscilloscope. Since spectrum analyzers display frequency vs. amplitude they are essentially an AC input device. This means that they cannot display DC values like an oscilloscope can. However, slowly varying DC is a perfectly valid input signal. The use of a spectrum analyzer allows the visualization of the harmonic content of any signal. An absolutely pure sine wave will have no harmonics (multiples of the fundamental frequency). Since this is impossible in the real world a spectrum analyzer will display the entire harmonic content...
The Network Analyzer
Essential in the development of RF circuits and systems, the network analyzer is a very specialized piece of test equipment. Combining a precise signal source and sensitive receivers, the network analyzer displays the amount of energy that is transmitted or reflected by a network. The term “network” refers to any linear circuit or system that signals travel through. This can include antenna arrays of all types also. Just because there is not a physical connection between the source and receiver doesn’t mean it is not a system! Network analyzers are useful for electrical engineering, electronics engineering, and communication systems design, and especially for microwave engineering. They are also known as a VNA, or vector network analyzer. It should a...
The oscilloscope, referred to as a “scope” going forward, is without a doubt the most versatile piece of test equipment on the engineer’s bench. No R&D or test bench is complete without one. In its most basic form, an oscilloscope displays voltage versus time with a calibrated display. The display takes the form of an XY graticule with calibrated vertical and horizontal divisions, known as a CRT. The feature that made the scope useful is the ability to trigger, or start a trace sweep, at precisely the same point in a repetitive waveform. This makes the trace stable and flicker free and easy to view. The primary characteristic of analog types is that there is a direct DC path from the input all the way to the deflection plates on the CRT displ...
Alternating-current (AC) power sources and loads can bring tremendous versatility to test systems and measurement applications, helping to precisely control the energy required for testing. Of course, selecting an AC power supply for different types of applications can be challenging. But the task can be made easier by better understanding key performance parameters that differentiate AC power supplies and loads, and matching AC source and load capabilities to meet current and future measurement requirements.
In a typical test environment, an AC power source will supply a repeatable, precisely controlled, low-distortion sinusoidal voltage to a device under test (DUT). The AC source must be capable of providing the amount of power required by the DUT. The power source should be acc...
Why Such High Costs for Test Equipment?
by Jack Browne in Measuring Progress
Most of us have waited on line at the workplace for a signal generator, or a spectrum analyzer, or even a digital multimeter. We may have even sneaked the use of a piece of test equipment from a coworker during their lunch break, to try to get some test results on a particular project. At any engineering facility worth its salt, test equipment will usually be in demand, and there is always the “engineering complaint” of there not being enough test equipment “in the house.” Many of us have asked, “Why doesn’t the company simply invest in more test gear so that the engineering staff can work more efficiently and effectively?” And most of us have received official corporate...
Featuring our Keithley 2420 High Current Sourcemeter
The Keithley 2420 High Voltage SourceMeter is a 60W instrument designed to source and measure voltage from ±5µV (source) and ±1µV (measure) to ±60V and current from ±100pA to ±3A.
Production test applications for the 2420 include resistors and resistor network devices that must be tested at higher current levels, thermistors, solar cells, batteries, and high current or medium power diodes, including switching and Schottky diodes.
The Keithley 2420 is also suitable for IDDQ testing of CMOS integrated circuits and monitoring the current consumption of battery-powered medical devices such as pacemakers.
View photo’s, specs and price information on the unit click here. ...
Axiom Test Equipment, a premier provider of electronic test and measurement equipment rentals and sales, announces the launch of a new, redesigned version of its website, www.axiomtest.com.
Key features of the site include a simplified, more contemporary design, an improved user experience with enhanced search functionality and navigation menus, and the ability to improve the site for future enhancements.
The redesigned website provides customers with a simplified and more user-friendly experience. It allows consumers to better interact with the site in order to find the equipment they’re looking for. Important additions to the website include a repair page where users can submit their repair requests online and receive a free evaluation from our in-house repair lab.
When most companies think about acquiring test equipment, they think about purchasing it. Before you sign that purchase order, however, you should consider renting the equipment instead. Here are nine reasons why it might be better to rent test equipment than buying it:
Renting equipment allows you to get equipment without having a capital budget. Capital budgets are generally approved only once a year, so what do you do if, all of a sudden, you need some test equipment in the middle of the year? You rent it, of course!
Rentals are paid for with expense dollars, not capital dollars. Because equipment rentals come out of your expense budget instead of your capital budget, there may be some tax advantages for your company. The expense of an equipment rental can be deducted i...
Where do you turn when it’s time to buy? What do you do when you need it now? Who can you trust?
When engineers need something, they need it fast. They want tested, functional equipment that is ready to hit their bench straight out of the box. Nobody likes the surprise of getting something that needs a tinkering and sometimes there’s no time to wait for your purchasing department to get its paperwork together. eBay just might be the solution.
eBay has come a long way since its initial growth in 1997. Long gone are the days of hobbyist trading their Star Wars collections via online auctions and weekend warriors taking their garage sales digital. Instead, eBay has emerged as a leading online retailer and premier e-commerce site where buyers can safely p...
I’ve dealt with a lot of different types of test equipment over the years, but I’m still amazed sometimes at what lands on my bench. The only way to explain this is it’s just plain odd. As if dealing with all the sophisticated circuitry in modern test equipment isn’t tough enough, I’ve had to deal with odd modifications, strange setups, and confusing control panels.
I cringe when I open up equipment and find odd modifications. Sometimes there are components missing from boards, circuit board traces that have been cut, or wires soldered to components on the board and or control knobs. Many times these modifications are not documented on the schematics that I have.
Manufacturers tell me that these are just engineerin...
Save time by analyzing broken equipment with nothing but your senses!
When confronted with a piece of equipment that’s not working, lots of things will be running through your mind. Modern test equipment is, after all, very complex, and lots of things can go wrong with it. Oh, the dreaded equipment that needs repair, where to start?
You may already have some information. The repair ticket might say, “Won’t turn on” or “Display not working.” That’s a good start, but I would suggest that before you open the toolbox or break out the schematics, you gather some troubleshooting information using your senses. Your senses--sight, hearing, touch, and even smell--can tell you a lot about what’s wrong with the gear and get ...
OK, I admit it. I’ve made mistakes that have led to blown power supplies and blown inputs and outputs on some of the equipment that I’ve worked on. You don’t have to make those same mistakes, though, if you follow these simple tips. Don’t blow it!
Check the voltage AND polarity of a replacement power adapter. Many instruments these days are using external power adapters, or “wall warts,” to provide power. Using a replacement adapter sounds easy enough, but not so fast. Not only do you have to ensure that the replacement adapter has the appropriate output voltage, but also that the output connector is wired properly. For some adapters, the center pin is positive and the outer conductor negative. For others, it’s the exact opposite, and I...
Six Preventive Maintenance Tips That Will Help Your Test Equipment Last Longer
I don’t have to tell you that test equipment is expensive. It’s expensive to buy, and it’s expensive to fix. That being the case, doesn’t it make sense to take some simple steps to keep your equipment from failing?
Here are six preventive maintenance tips that will:
• extend life of your test equipment
• reduce equipment downtime
• ensure that your test equipment meets specs
#1. Keep it clean.
Heat kills, and the biggest culprit when it comes to overheating is dirt. Dirty fan filters and clogged ventilation holes impede the flow of air through your test equipment, meaning that the components inside are not being cooled properl...