Astronomical telescopes (optical, not radio) are divided broadly into two categories, refractors and reflectors. A refractor consists of a relatively long tube with a lens called the objective lens semi-permanently mounted at the far end and an eyepiece mounted at the end nearest the observer. The telescope will work if the eyepiece, like the objective, […]
New Articles
The basics of regenerative braking
Regenerative braking is an inherently good idea, particularly in a world that still relies heavily on fossil fuels and is threatened by the inevitable planet-warming effects that are the result. A moving vehicle, to take one example, possesses a certain amount of kinetic energy. If it is to be stopped or, while descending a grade, […]
A quick review: The inexpensive Rigol DS2102A oscilloscope
Oscilloscopes are indispensable in the laboratory, advanced repair shop and educational setting. Because the higher-end models cost thousands of dollars, engineers on limited budgets must seek less expensive alternatives. One of these is the Oscium, which takes advantage of the computing power and display capability of Mac products such as iPhone, iPads or iPods. If […]
Basics of battery banks for wind and solar installations
More and more wind and solar installations are incorporating battery banks as a means of letting the wind or solar generators maintain a level output to the grid in the event of temporary interruptions such as passing clouds or a sudden lull in the wind. Unfortunately, today’s best batteries still have a finite life expectancy. […]
Communication systems and the NEC
Many people believe the National Electrical Code (NEC) has jurisdiction over electrical systems operating at a voltage only over a specified level. This is not at all true. The NEC covers all non-utility electrical installations regardless of voltage or available energy level. The purpose is to mitigate hazards to persons or property resulting from the […]
Bonding and grounding differences
Where the National Electrical Code (NEC) has been enacted into a jurisdiction’s body of law, it mandates every aspect of electrical installations from the point of view of safety. A lot of attention is focused on grounding and bonding. These related concepts are covered in detail in NEC Article 250. Grounding and bonding as electrical […]
Basics of induction
Building on the work of others, particularly Humphry Davy, Hans Christian Ørsted and Alessandro Volta, English researcher Michael Faraday formulated his Law of Electromagnetic Induction. This most basic of all laws governing electromagnetism quantifies the interaction of a magnetic field and an electric circuit, producing electromotive force (EMF) or in the language of technicians and […]
USB-based real-time spectrum analyzers hit
7.5 GHz with 40 MHz capture bandwidth
USB-based real-time spectrum analyzers target design, spectrum management and wireless transmitter installation and maintenance applications. The new RSA500 and RSA600 series of analyzers from Tektronix offer frequency coverage from 9 kHz up to 7.5 GHz with 40 MHz acquisition bandwidth, a measurement dynamic range from -161 dBm/Hz Displayed Average Noise Level, and up to +30 […]
The Doppler effect in EM and cellular phones
Prior to 1800 the Doppler Effect was unknown because there weren’t speeding railroad trains or motorized fire trucks with blaring sirens, so the phenomenon was outside of human experience. The first person to take note of the Doppler Effect and after whom it was named was an Austrian, Christian Doppler. He had poor health and […]
Basics of setting up electrical service in buildings
Any building or electrical installation must have an electrical service unless it has an onsite power supply or connects via feeder to some other installation that itself has a service. Requirements and definitions reside in National Electrical Code (NEC) article 230, Services. It defines an electrical service as the part of the installation from the […]