Electrical power moves through a conductor when opposing dc or ac voltages are applied at opposite ends. Charge carriers — free electrons or electron holes in semiconductors, ions in electrolytes – migrate toward the opposite poles. Metals, with abundant free electrons, have high conductivity. All conductors are partial insulators and all insulators are, to some […]
Digital caliper, Pt 1: Background and predecessors
Use of electronics and capacitive-based position sensing have transformed the caliper, a fundamental and essential instrument of precision linear-dimension measurement. Making precise measurements across small distances of up to several inches or tens of centimeters is an obvious and fundamental requirement of modern metrology, research, and mass production. But how can that be done accurately, […]
Cathode ray tube vs. flat screen displays in oscilloscopes
Prior to the digital revolution in electronic instrumentation, oscilloscopes displayed waveforms on cathode ray tube screens. Modern digital oscilloscopes universally have flat screens. The flat screen is light, thin, consumes far less energy, and is less expensive to manufacture. All agree that it is a great improvement. The one advantage of CRT technology is that […]
The difference between metal conductors and waveguides
Manufacturers of instrumentation are striving to satisfy the demands of modern electronics which continuously require greater bandwidth. There has been a growing tendency to incorporate waveguides, ranging from extremely small units soldered into printed circuits, to larger devices mounted in enclosures. The natural question that arises is how waveguides differ from ordinary wiring, and why […]
Difference between synchronous and asynchronous (induction) motors
All rotary electric motors, ac and dc, operate because of the interaction of two magnetic fields. One is stationary and is (usually) associated with the motor’s outer enclosure. The other rotates and is associated with the motor’s spinning armature (also called its rotor). Rotation is caused by the interaction between the two fields. In a […]
Analog and digital modulation and modulation measurements
In amplitude modulation (AM), the amplitude of a carrier wave whose frequency remains constant changes in response to the modulating signal. In frequency modulation (FM), it is the frequency of the carrier that varies with the amplitude of the modulating signal. The carrier frequency deviates more when the modulating signal amplitude is higher. There are […]
Three-phase testing basics – Mitigating harmonic current
An electrical conductor warms up when it conveys current. If the heat is high enough the conductor can be damaged, so it is beneficial to limit current flow. Three-phase electrical distribution systems are highly effective in limiting current flow without reducing the amount of power delivered to the load. They do this by separating phases […]
Safety guidelines for hipot testing and setting up a safe testing area
A few simple steps ensure testing takes place safely when potentially lethal voltages and currents are involved in the testing process. Kevin Clark, Vitrek Inc. Hipot testing has long been a standard procedure for assuring the electrical safety compliance of electronic equipment. Early commercial hipot testers were actually not much more than a variac-driven step-up […]
Understanding and testing asynchronous logic
Traditionally, computer and instrumentation engineers work with synchronous logic, where a global clock circuit imposes a timing structure to which all circuits down to the components level adhere. In synchronous logic, an autonomous oscillator outputs a square wave that never varies in frequency or amplitude. At the rising edge (sometimes falling edge) a potentially vast […]
The difference between MDO and MSO displays with time domain and Fast Fourier Transforms
Mixed-domain oscilloscopes and mixed-signal oscilloscopes differ significantly in how they display waveforms. Both are useful because they permit users to simultaneously view different electrical aspects of equipment under investigation. The MDO displays a single signal simultaneously in the time and frequency domains, demonstrating how they change together. The MSO displays two different signals in the […]
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