Hysteresis might be defined as something that happens when the physical state depends upon its history. The classic example of hysteresis in action is the residential thermostat. It has built-in hysteresis to prevent rapid cycling. It’s low cut-in and high cut-out levels are designed to prevent the heating/cooling system from rapid switching, which would quickly […]
The hot and cold of thermocouples
The common temperature probe contains a thermocouple consisting of two dissimilar metals welded together to form an electrical junction. A voltage that varies with temperature is generated. Slightly less accurate than resistance temperature detectors (RTDs), thermocouples cover a wide temperature range and respond quickly. Combinations of different metals create different voltage responses. All dissimilar […]
Lasers and how to measure their output
Laser is an acronym for light amplification by stimulated emission of radiation. Lasers, of course, started out as comprised of discrete components. The most basic laser consists of a cylinder containing the lasing medium, a material that emits light when exposed to an outside source of energy. The gain medium can be gas, liquid, solid […]
Understanding electro-optic modulation
The electro-optic modulator is used to modulate a beam of light. Laser-controlled modulators are capable of operating in the gigahertz range, and modulation may be imposed on the amplitude, phase, or polarization of the beam. The component that makes this possible incorporates an element that exhibits an electro-optic effect, a change in its optical properties […]
Understanding and measuring optoelectronic oscillators
The problem with even a high-end electronic oscillator–such as a quartz crystal oscillator, dielectric resonator, sapphire resonator or air dielectric resonator–is that as the output frequency rises, excessive phase noise also rises. Optoelectronic oscillators are not subject to this and other dysfunctional high-frequency characteristics, and consequently they are suitable in certain exacting 21st century applications […]
Working with scope-based spectrum analyzers
The spectrum analyzer is a member of the oscilloscope family. An electrical signal is fed, by means of a BNC cable or probe, into an input port on the front panel, and its graphic image appears on the LCD screen. But rather than the oscilloscope’s familiar time domain graph, in which amplitude in volts is […]
Basics of voltage doubler circuits
Voltage can be doubled (and therefore multiplied by any power of two using cascading devices) through purely electronic means without resorting to a transformer. Voltage-current ratios apply, so doubling is not a question of getting free electrical energy that did not previously exist. Doubling the voltage and thus reducing the current available at the output […]
Basics of troubleshooting power supplies
When a piece of equipment turns up completely dead, one of the first things to look at is the power supply. If using an oscilloscope for this sort of troubleshooting, it should be a hand-held, battery-powered instrument isolated from ground, at least at the outset. The reason is there may be internal voltages that are […]
COVID-19 and climate change
A single coronavirus particle mutated and survived the transition from animal carrier to human victim, and so far with verified U.S. cases exceeding one million, there is no known therapy or protective vaccine. An unexpected consequence of mediation efforts is that for the first time in generations, Los Angeles and other urban areas have blue […]
Difference between phase distortion, phase modulation, and frequency modulation
The concepts of signal phase modulation and signal frequency modulation, and the difference between them, are often a source of confusion. Ditto for the related idea of phase distortion. Here, we’ll try to clarify things. To understand phase distortion, recall that any waveform can be considered to be a sum of sine waves of different […]
