In electrolytes, traveling ions are the charge carriers, playing the role of electrons in a metal conductor. Ionic solutions, which are electrolytes, vary in resistivity depending on small changes in concentration. Ohmmeter probes dipped in a glass of distilled water produce a high-ohm reading, while adding a pinch of salt greatly increases the conductivity. Electrolytes […]
Basics of QAM reception and its measurement
A conventional AM broadcast generally begins in the studio as a music or voice audio signal. The audio signal modulates the amplitude of a radio-frequency electrical signal. This AM signal–also referred to as double-sideband amplitude modulation to distinguish it from single-sideband modulation–produces equal frequency sidebands on either side of the center frequency. In single-sideband modulation […]
Measuring the Hall effect
The Hall effect, first described by Edwin Hall in 1879, results in an electrical output when a thin metal plate is immersed in a magnetic field of sufficient strength. The magnetic field must be perpendicular to an electrical current conducted through the plate. The Hall effect voltage potential depends upon the strength of the magnetic […]
When RMS amplitude is important and when it isn’t
There are a variety of ways to specify the amplitude of a waveform. Here are a few of the most common forms and a primer on when specific types are most appropriate. In physics. amplitude is the absolute value of the maximum displacement from zero during one period of an oscillation. In electrical waveforms, amplitude […]
Detecting gravitational waves
Gravitational waves were first proposed by Henri Poincaré in 1905 and further described in Albert Einstein’s 1916 General Theory of Relativity. Gravitational Waves are powerful perturbations of the space-time continuum. However, the sources of gravitational waves we know about are enormously distant and therefore faint by the time they reach earth–like EM radiation, their intensity […]
Testing vulnerabilities in programmable logic controllers
Had you examined the controls handling automotive assembly lines before the mid 1970s you would have found cabinets full of relays, cam timers, drum sequencers and hardwired controllers. All these controls had to be swapped out or modified to handle line retooling during a model-year change. To reduce the cost of such changeovers, General Motors […]
The difference between noise and jitter
Electronic noise and jitter are closely related phenomena, but they are not the same. While noise typically manifests as amplitude distortion, jitter pertains to timing of digital signals. Either of them may be caused by outside interference or internal sources. Noise can be seen in an oscilloscope time domain display as a noticeable thickening of […]
Basics of spectrometers and spectroscopy
The spectroscope is an instrument that separates white or near-white light into constituent colored bands as in a rainbow. The spectra can be projected onto a screen, viewed through a lens assembly, or photographed. The most elementary spectroscopes consisted of a single prism as used by Isaac Newton, described in an early treatise. He caused […]
Product review: Pico VNA 108 8.5-GHz vector network analyzer
The vector network analyzer (VNA) is an advanced member of the oscilloscope family of electronic instruments. The DUT may be as simple as a single resistor or conductor. The VNA can also operate as a time domain reflectometer, measuring the distance to and nature of a fault, impedance anomaly, complete break or short in a […]
Basics of measuring fuel cells
A fuel cell converts oxygen or another oxidizing agent and hydrogen or some other fuel into electricity and heat. A third byproduct, depending on the fuel used, is methane or another non-earth-friendly substance. But the most basic fuel cell combines hydrogen and oxygen to produce pure water. This simple, long-lasting device with no moving parts […]
