Experimenters beware! If you think it might be instructive to dismantle a microwave oven and power up the magnetron to make a space gun, don’t do it. A microwave gun (called a magnetron) in a state other than as manufactured has numerous potential hazards. (Nevertheless, you can find a lot of YouTube videos describing exactly […]
The difference between scanning electron microscopes and tunneling scanning electron microscopes
Compared to an optical microscope, the electron microscope achieves far greater resolution and magnification by taking advantage of the wave aspect of electrons. An electron’s wavelength is typically 1/100,000 that of visible light. Resolutions of 50 pm and 10 million-X magnification have been achieved, far better than the 200-mm resolution and 2,000X magnification of a […]
The difference between CCD and CMOS image sensing
Charge-coupled devices (CCDs) and complementary metal-oxide-semiconductor (CMOS) technology have been in fierce yet friendly competition. Fierce because valuable market share is contested, friendly because the rival digital camera technologies have much in common. It is ironic that the more-costly CCD sensor is used in the most advanced astrophotography instruments and also in low-end point-and-shoot cameras, […]
Testing PV inverters
A photovoltaic, or PV, inverter converts the dc output of a solar cell or array into ac that can feed directly into the electrical grid (Grid Tie) or be used by a local electrical grid (Off-Grid). Solar PV inverters have special functions adapted for use with photovoltaic arrays, including maximum power point tracking (MPPT) and […]
Tools for optimizing circuit bias
If a semiconductor or vacuum tube is to accurately reproduce or amplify signals on its input, it must have on its input a non-time-varying dc voltage, i.e. dc bias, the purpose of which is to keep the device in its linear operating range. Otherwise, the input signal to be reproduced may drive the device beyond […]
Difference between Cat 5e and Cat 6a cable
Cat 5e (enhanced) and 6a (augmented) are the most frequently-used media in residential and commercial Ethernet networks. Cat 6a has higher bandwidth and is faster, but the less expensive Cat 5e is often chosen when adequate for the application. It performs well up to 100 MHz. In contrast to coaxial cable, used in the first […]
User review: Tektronix AFG31000 arbitrary function generator
If you see the word “arbitrary” in conjunction with a function generator, it signifies the instrument’s capability to customize waveforms at the user’s discretion. The new Tektronix AFG31000 Series arbitrary function generator incorporates this technology on top of its traditional library of a dozen basic waveforms: sine, square, ramp, pulse, noise, sin (x)/x, dc, Gaussian, […]
Batteries, battery analyzers and battery testers
The Leyden jar, invented by the Dutch physicist Pieter van Musschenbroek in 1746, preceded what we today call the battery. Originally, “battery” denoted several units connected in series or parallel. Thus, there could be a battery of Leyden jars. Actually, the Leyden jar works on a principle completely different from that of a battery. It […]
What you need to know about information theory
A lot of the testing and verification activities of EEs today centers on concepts having a theoretical basis in Claude Shannon’s (of Nyquist-Shannon renown) article titled, A Mathematical Theory of Communication, which appeared in 1948 in the Bell System Technical Journal. Shannon’s full treatise gets to be quite mathematical. Fortunately, some of the fundamental concepts […]
Understanding total harmonic distortion measurements
Most electronics engineers and technicians have a good understanding of total harmonic distortion (THD). But there are a few elusive details that come into play during THD measurements. THD is the ratio of the sum of the powers of all harmonic components to the power of the fundamental frequency. Properly speaking, the fundamental frequency is […]
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