A digital signal can be derived from the original time-varying, continuous analog signal by creating a sampled sequence of quantized values. It is intuitively evident that the fidelity and resolution of this quantized signal is based upon the number of samples taken per unit of time. Harry Nyquist published an early version, later further formalized […]
Measuring and using static electricity
Many moons ago, a future member of our editorial staff was playing with his very first multimeter. He was a farm kid. One of his first experiments was to put the negative lead of the meter on a ground rod and the positive lead on one of the metal bands used to reinforce the interlocking […]
Coaxial cable myths and misunderstandings
In this age of misinformation, you can add coaxial cable to the list of items for which it is easy to get steered wrong based on internet searches. Much of the bogus online commentary about coax relates to cable loss, cable impedance, and standing waves. Here are a few basics that may help sort the […]
Can something consume energy without emitting a field?
The editorial offices of Testandmeasurementtips.com recently received a letter from an individual who headed up a group of investigators of paranormal phenomenon. It was a serious letter. To summarize, the group had concluded there was no legitimate method to record the activity of an alleged haunting. But the writer did have a question for us, […]
How big is the band gap? A heated discussion
There’s a trick with a soldering iron can be used to determine whether an unidentified semiconductor is n-type or p-type. In essence, it determines whether the majority carriers are holes (p-type) or electrons (n-type). Just as heat makes a gas expand (PV=nRT), the hot tip of a soldering iron makes carriers expand away from the […]
The difference between signal under-sampling, aliasing, and folding
Most engineers today are sensitive to problems that arise when digital measurement instruments try to capture signals containing frequencies that are too high for the sampling circuitry to handle–undergrad EE programs typically cover Nyquist’s sampling theorem. Nevertheless, there are terms associated with sampling problems that sometimes get confused. Probably the three concepts most likely to […]
Difference between a waveguide and transmission line
As electronics migrates to higher and higher frequencies, the media routing electronic signals to their intended destinations grow increasingly exotic. This is particularly true as communication technology moves to 5G frequencies which are characterized by millimeter wave transmissions. In this frequency range, engineers are more likely to encounter waveguides and transmission lines rather than ordinary […]
The difference between the Faraday effect and Faraday’s law of induction
Michael Faraday is probably best known for his law of induction. But he also discovered the Faraday Effect in 1845 which states that light and electromagnetism are related phenomena. Faraday asserted that, in fact, light is a form of electromagnetism, anticipating James Clerk Maxwell by nearly two decades. Faraday stated that when a solid or […]
Does Kirchhoff’s Voltage Law really fail?
Gustav Kirchhoff (1824-1887) was an accomplished Prussian physicist and instrument maker, and best known for his current and voltage circuit laws. Kirchhoff’s first circuit law, known as his current law, states that the algebraic sum of currents in a network of conductors meeting at a point is zero. Kirchhoff’s second circuit law, known as his […]
What is Fourier transform IR spectroscopy?
Most EEs probably think of a Fourier transform in terms of an operation that converts time-based waveforms on a scope into their component frequencies. But Fourier transforms also play a role in infrared spectroscopy. It might be easiest to explain Fourier transform infrared spectroscopy by contrasting it with conventional spectroscopy. Also called “dispersive spectroscopy,” the […]
