A central concept in magnetism is the domain, discovered in 1906 by Pierre-Ernest Weiss. He theorized that in any magnetically permeable material, a large number of mostly microscopic regions existed as separate walled-off entities. In each of these entities, called domains, the atomic moments align in parallel when magnetized. But the alignment of individual domains […]
Basics of Fourier transforms
Joseph Fourier (1768-1830), in his principal work, “On the Propagation of Heat in Solid Bodies” (1807), laid the groundwork for what is now known as the Fourier Transform. In years to follow it was modified by others to make it more generally applicable. Today the basic insight is central to our understanding of a broad […]
Differences between stand-alone and scope-based spectrum analyzers
Most oscilloscope manufacturers also offer an extensive line of spectrum analyzers. There are similarities as well as differences between these two distinct instruments. The oscilloscope is optimized to display signals in the time domain, its default mode. Additionally, pressing Math>FFT, the same signal appears in the frequency domain. In the Tektronix MDO (mixed domain oscilloscope), […]
The ups and downs of oscillators in test equipment
Examine the low-frequency signal source in many kinds of test equipment and you are likely to find a harmonic oscillator. A harmonic oscillator typically consists of an amplifier that gets its input from its own output. A part of the output feeds back to input while the rest is an output signal. To support oscillations, […]
Checking power line quality with test instruments
The average homeowner probably doesn’t think about the quality of the electrical power coming out of household wall sockets. But that’s not the case for large industrial facilities where capacitive, inductive, and non-linear electrical loads can be large enough to distort the ac waveform. In those cases, electrical power quality becomes an important measurement. Electric […]
Understanding instrumentation for measuring total harmonic distortion
When discussing total harmonic distortion (THD), the fundamental of the wave in question is known as the first harmonic. Quantifying THD, therefore, begins with the second harmonic. Theoretically, the number of harmonics is limited only by some maximum frequency based on minimum quantum wavelength. In reality, however, we are interested in a relatively small number […]
Morse code, the first serial communication protocol
Today we tend to take for granted the fact that even PC-based oscilloscopes can automatically record and decode packets or frames sent via serial protocols such as 1-Wire, RS-232, and Ethernet. But back in olden times, the decoding of serial protocols was a job for humans. We are speaking, of course, of what was probably […]
The super-cold measurement science of superconductivity
Ordinary conductors such as copper and silver exhibit less resistance as the temperature drops. But even near absolute zero they still have some resistance. With true superconductivity, the resistance of certain materials drops to precisely zero when they hit a certain critical cold temperature. This type of superconductivity is a quantum mechanical process that involves […]
Basic instrumentation for the electronics workbench
Engineers and technicians doing design, development, and testing have a wide range of instrumentation available for use on the test bench. So it might be useful to consider which instruments are considered the “basics” for the general case. Here are a few nominations along with the device properties that are generally considered “must-haves.” The unassuming […]
Difference between linear amplitude and decibel amplitude
In the time domain, amplitude, the dependent variable, is shown in volts relative to the Y-axis. In an oscilloscope display, for example, we may see branch circuit voltage as 325 V peak-to-peak, but the meaningful figure is 115 to 120 V, depending on your distance from the transformer, wire size and loading. One hundred and […]
