Functionally, servomotors and steppers overlap. Both can rotate their shaft a portion of a turn and hold that position for any length of time as determined by an external controller. A step motor is one of several specific positioning motor constructions whereas servocontrol refers to a type of control that involves feeding back information about […]
Basics of stepper motors
There are several varieties of stepper motors, having somewhat different types of commutation and operating characteristics, but they all have in common the ability to spin continuously in either direction or to turn a part rotation and then stop, with or without holding torque. In this, they resemble the servomotor. But the servo typically operates […]
Explained: The earth’s magnetic field
Since ancient times, terrestrial explorers and mariners at sea have known that a magnetized needle would point north. This beneficial effect of the earth’s magnetic field helps make life on earth possible. The earth’s magnetic field keeps the solar wind at bay. Without it, this stream of plasma released by the sun would strip off […]
Understanding skin effect
Ohm’s law states that E = I X R — volts (electromagnetic force) is equal to amps (intensity) times ohms (resistance). When the equation is used together with the power law — volts times amps equal watts — it is possible to derive several formulas, solving for various unknowns. All of this is conveniently organized […]
The standard model of particle physics
Isaac Newton’s classical view of light (consisting of very small material bodies) appeared to lose validity following Thomas Young’s double-slit experiments. These convincing demonstrations in the first decade of the nineteenth century showed that light must propagate like ocean waves, but transverse rather than normal to the direction of travel. Then, once again, uncertainty reigned […]
Thomas Young and the double-slit experiment
Isaac Newton propounded in his great work Opticks (1704) that light consists of a flow of particles. Generations of students and researchers have accepted this idea. Light was believed to be composed of large numbers of billiard-ball type material bodies, visualized as spherical objects that traveled through vacuum and non-opaque regions with no luminiferous medium […]
Basics of light polarization
Black body radiation, originally described by Gustav Kirchhoff in 1860, consists of light and other electromagnetic radiation that is emitted by a material object that is not reflective. The frequency and intensity of the radiation depends upon the temperature of the body. As anyone who has heated metal with an oxy-acetylene torch is aware, the […]
Basics of molecular-scale electronics
In the race to achieve higher speed computation, conventional lithography-based Very Large-Scale Integration (VLSI) is bumping up against a brick wall that threatens to disrupt Moore’s Law which states that the number of transistors in a dense IC doubles about every two years. That formulation is more of an observation of past performance than an […]
Basics of multiplexing
Multiplexing should be understood not as a specific operation but rather as an end product that may be achieved with different methods, sometimes in combination. The rationale is to economize on limited resources, particularly cabling or wireless bandwidth. The archetypal format would be to use a single pair of telegraph or telephone wires to simultaneously […]
Basics of LEDs
Every solid-state diode is a light-emitting diode (LED). The difference is that conventional solid-state diodes are not configured to produce sufficient light of the proper frequency, directed properly so it is useful as a source of visible light. A solid-state diode is composed of two semiconducting layers, frequently made of crystalline silicon, that have been […]