Here’s a quick review of some basic instrumentation common to most engineering work benches. Ammeter The ammeter is the basis for many other electrical measuring instruments. Whether you are measuring volts or ohms, essentially inside the instrument you are measuring current. Measurement of current in a circuit is somewhat problematic because all the electrical energy […]
Another Covid causality: The James Webb telescope
NASA has announced it will pause work on the James Webb Space Telescope because of the ongoing COVID-19 pandemic. The launch is still currently on the books for 2021, but there are questions about whether that date will hold. The James Webb Space Telescope, successor to the Hubble and Spitzer instruments, was originally scheduled to […]
The difference between instrumentation and differential amps
Many of the test instruments used in industry today have inputs based on instrumentation amplifiers. This kind of amplifier, sometimes abbreviated as InAmp, is itself based on a more fundamental amplifier setup, the differential amplifier. It can be helpful to understand how these two devices differ. A differential amplifier ideally amplifies the difference two input […]
The difference between SWR and TDR meters
In setting up transmission lines, it is often desirable to measure the amount of signal reflection. The relevant metric is the standing wave ratio (SWR). SWR is defined as the ratio between the amplitude of a partial standing wave at antinodes [max] to the amplitude of the adjacent mode [min]. Thus a ratio of 1.5:1 […]
Do you really need a VNA when a scalar network analyzer might do?
Network analyzers measure network parameters of electrical networks, such as two-port amplifiers and filters. The instruments characteristically operate at 5 Hz to 1.05 THz, mostly at the higher end, though some models are sensitive down to 1 Hz. These instruments are available in two varieties: scalar network analyzers, which measure only the amplitude of the […]
The therapeutic uses of RF energy
Discussions of the upcoming 5G technology sometimes focus on whether or not the millimeter-wave frequencies involved can damage human life. What gets less press is that radio frequency energy in other bands can be therapeutic. It can be useful to review a few of these uses to understand the beneficial role RF energy can play. […]
Testing transistors with a voltmeter
A bad transistor can sometimes be detected by its partly burned or distorted appearance, but more often there is no visible indication. One approach to troubleshooting is to substitute a known good component, but that is a costly way to go. Also, it is not reliable because an outside defective component can instantly destroy the […]
Will 5G make earth-bound radio telescopes impractical?
Though 5G is a promising technology, astronomers and Earth scientists are worried that 5G frequencies could interfere with the scientific use of previously quiet parts of the electromagnetic spectrum. The Federal Communications Commission recently came out with rules allowing experimental devices to use frequency bands between 95 GHz and 3 THz. Scientists see several problems […]
Signal acquisition in the Tektronix MDO3000 series oscilloscope
Most modern digital storage oscilloscopes have either two or four analog channels. One or two channels suffice for most work, but it is just good to know you have four, notwithstanding the substantial cost differential. As for the digital channel count, it is typically 16, handy when working on a parallel bus. All these digital […]
Measuring and abating jitter
Electronic noise results in spurious signals (spurs) or distortion in amplitude, frequency or both. Jitter refers to unwanted variation in frequency, particularly in digital pulses and typically in the clock signal. Timing disruptions negatively impact system performance, particularly in ADCs, where sampling occurs, and in DACs. We’ll discuss causes of jitter, its detection and measurement […]
