Often a transmission line is buried, concealed behind finish surfaces, or otherwise not readily accessible. So it is difficult to locate faults by means of visual inspection. It is, however, feasible to locate such discontinuities via a test instrument known as the time domain reflectometer (TDR). The TDR is sometimes compared to a radar installation, […]
FAQ
ARB waveform generators and measuring amplifier gain
When it comes to amplification, the principal parameters are gain and fidelity of the output relative to the input. Gain, denoted by β (Greek letter beta), is the ratio of output voltage, current or power to input. An amplifier by definition has a power gain greater than one. Measurements that characterize amplifier gain serve as […]
The difference between testing thyristors and triacs
The thyristor is a two- or three-pin device comprised of four alternating P- and N- layers. It is also known as a silicon-controlled rectifier and is often used in light dimmer switches, speed controllers for electric motors, and switch gear for high-voltage dc power transmission systems. The thyristor does not function as an amplifier–its output […]
What is a load coil and how do you measure it?
The textbook description of an inductor often involves a coil of wire. Of course, any material other than a perfect ideal insulator has theoretical inductance. All the windings do is multiply the effect by creating overlapping fields. It’s good to keep in mind that inductance is measurable in many non-coils, such as power transmission lines, […]
Is it possible to image an electron?
The electron has close to zero mass, a negative charge, and revolves in an orbit around its atomic nucleus or, alternately, moves through space or through a conductor, in which it is a charge-carrying free electron. An electron is also a fermion, which means it follows the Pauli exclusion principle: No two electrons can occupy […]
Understanding decibels and decibel measurements
Decibels, (derived from bels, old units which, like unwieldy farads, are rarely used) are convenient and user-friendly terms for expressing the ratio between two amounts of power on a logarithmic scale or the amount of change, amplification or attenuation, over time of a single amount of power. In power and sound ratios, the factor is […]
Measuring and specifying microphones
One aspect of the work-at-home/stay-at-home environment of the past year has been an increased emphasis on podcasts, online meetings, and online video events. That’s why there’s more interest in microphone technology among those interested in producing a higher-quality experience. Here’s a short run-down on microphones and how they are typically measured and quantified. A microphone […]
Thanks, Pythagoras, for the basic science behind the theodolite
Pythagoras was a larger than life pre-Socratic philosopher, born on the island of Samos. The Pythagorean Theorem relates the lengths of the three sides of a right triangle. Undoubtedly the most familiar theorem in mathematics, it had been known previously in Mesopotamian, Indian and Chinese cultures, but it was elaborated, made part of the over-all […]
Antennas and antenna measurements
Most antenna designs operate via the resonance principle, which is based on the fact that electrons moving through a conductor reflect back toward the power source when encountering a discontinuity. When current, caused by a radio signal’s induced voltage, reaches the end of the antenna element, it is reflected, travels in the reverse direction, and […]
Don’t get zapped — Using test instruments safely
Most engineers think they’ve minimized the chance of nasty surprises around the test bench when they’ve grounded their instruments and perhaps kept one hand in their pocket when working around high voltages. That said, there remain electrical hazards that are less obvious. They involve the electrical wiring and the environment around the lab. To begin, […]