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 […]
FAQ
Measuring efficiency in solar photovoltaic cells
Single-junction solar cells have a maximum theoretical efficiency of 33.16%, the Shockley-Queisser limit. But there are work-arounds that permit solar array designers to surpass that limit on a square-foot basis. The maximum solar conversion efficiency of around 33.7% happens at a 1.34 eV band gap and is subject to several assumptions. By way of review, […]
Up close and personal with magnetrons
Today most people’s experience with a magnetron is as a source of microwaves in residential microwave ovens. The microwave radiation is conveyed to the oven section via a waveguide. Microwave ovens are also a favorite target of scavengers and experimenters who like to take things apart. The magnetron is one frequently scavenged component. You can […]
The back and forth of interferometer technology
Conceptually, the interferometer is a relatively simple instrument that compares two distances typically differing only by a slight amount. Two waves, often coherent light waves, reflect from standard mirrors mounted at the object under investigation. The light from one mirror passes through a half-silvered mirror while the light from the other reflects from the back […]
Difference between measuring resistance and conductivity
Generally, an electrical conductor is a long solid rod, often insulated. It may be rectangular, like the electrician’s bus bar, irregular in cross section, or it may be merely a conductive path through the atmosphere, created by a process of ionization. Most electronics professionals have measured the resistance of conductors typically using a volt-ohm meter. […]
Working with oscilloscope probes, part two
The oscilloscope can be viewed as essentially a voltmeter that incorporates a dynamic display. But the oscilloscope can also make use of a current probe to convert current information into corresponding voltage potentials displayed in units of Amperes. The current-to-voltage conversion takes place within the current probe which operates like the electrician’s clamp-on ammeter. The […]
A fractional Fourier Transform? Yes, there is such a thing.
The Fourier Transform, outlined by French mathematician and physicist Joseph Fourier (1768-1830) in The Analytic Theory of Heat (1822), asserted that any function of a variable, whether continuous or discontinuous, can be expanded in a series of sines of multiples of the variable. His focus at the time was the propagation of heat in an […]
The difference between measuring magnetic flux and magnetic fields
Simply stated, a magnetic field is analogous to electrical voltage, while magnetic flux is analogous to electrical current. A magnetic circuit is analogous to an electrical circuit with important differences. Electromotive force in an electrical circuit corresponds to magnetomotive force. Resistance and its reciprocal, conductance, in an electrical circuit corresponds to reluctance and its reciprocal, […]
Practical measurement of feedback loops and their stability
Feedback is relevant not only to electronic circuits but also to all kinds of natural and human-based phenomena ranging from mechanical engineering to economics and finance. Feedback emerges when one or more system outputs are connected back to system inputs. If polarity is inverted, it is an instance of negative feedback, which in electrical circuits […]
Basics of CMOS and measuring CMOS logic parameters
Complementary metal-oxide semiconductor (CMOS) fabrication uses p-type and n-type complementary and symmetrical pairs to implement logic functions. The fundamental building block of the CMOS circuit is the MOSFET semiconductor, which enables it to operate at far lower current levels than bipolar transistors. This current reduction comes via pairs of p-type and n-type MOSFETs connected gate-to-gate […]