LED’s and photovoltaic cells play increasingly prominent roles in our world. Both are semiconductor diodes. The LED or light-emitting diode emits light while the photovoltaic cell converts light to electricity. The LED is a diode that emits light only when forward-biased. Under a forward voltage bias, electrons cross from the n-region and recombine with the […]
Bit errors and ADC testing
Most engineers are introduced to the basic performance parameters of analog/digital converters in school. So specifications such as SNR, SINAD (Signal-to-noise and distortion ratio), ENOB (Effective Number of Bits), and THDA (total harmonic distortion analysis) are all familiar ADC terms found in ADC data sheets. Ditto for an INL error, described as the deviation, in […]
Review: Using the Fluke 438-II motor analyzer
Fluke has come out with another superb electrical measuring instrument. It is the Fluke 438-II Motor Analyzer. Owners of the previous Fluke 435-II Power Quality Analyzer can download an upgrade that will add Motor Analyzer functions to their existing equipment. Full documentation including specifications and owner’s manuals for both of these members of the oscilloscope […]
The difference between an electrometer and a Geiger counter
In 1895 William Roentgen observed X-rays although he could not explain their mechanism. The following year Henri Becquerel demonstrated that certain compounds of uranium emitted radiation that resembled X-rays. He showed this activity differed from the phenomenon of phosphorescence. The radiation seemed to be emitted continuously from the uranium. Did this violate the well-known principle […]
The difference between TDR instruments and scope-based TDR measurements
Often a transmission line is buried, concealed behind finish surfaces, or otherwise not readily accessible. So it is difficult to locate faults by means of visual inspection. It is, however, feasible to locate such discontinuities via a test instrument known as the time domain reflectometer (TDR). The TDR is sometimes compared to a radar installation, […]
ARB waveform generators and measuring amplifier gain
When it comes to amplification, the principal parameters are gain and fidelity of the output relative to the input. Gain, denoted by β (Greek letter beta), is the ratio of output voltage, current or power to input. An amplifier by definition has a power gain greater than one. Measurements that characterize amplifier gain serve as […]
Does a planet have a capacitance?
The self-capacitance of Earth is approximately 710 μF, assuming the free-space dielectric to be a vacuum. The capacitance of Mars is 378 μF. At first glance, it may not be clear where these figures comes from or how a planet can have a capacitance. And if a planet has a capacitance, might it also have […]
Is it possible to image an electron?
The electron has close to zero mass, a negative charge, and revolves in an orbit around its atomic nucleus or, alternately, moves through space or through a conductor, in which it is a charge-carrying free electron. An electron is also a fermion, which means it follows the Pauli exclusion principle: No two electrons can occupy […]
Understanding decibels and decibel measurements
Decibels, (derived from bels, old units which, like unwieldy farads, are rarely used) are convenient and user-friendly terms for expressing the ratio between two amounts of power on a logarithmic scale or the amount of change, amplification or attenuation, over time of a single amount of power. In power and sound ratios, the factor is […]
Measuring and specifying microphones
One aspect of the work-at-home/stay-at-home environment of the past year has been an increased emphasis on podcasts, online meetings, and online video events. That’s why there’s more interest in microphone technology among those interested in producing a higher-quality experience. Here’s a short run-down on microphones and how they are typically measured and quantified. A microphone […]
