Consider the task of performing a capacitance test using an LCR meter or a good multimeter such as the Fluke 287 True RMS Multimeter. If the capacitor under test is an electrolytic or film-based device, the main measurement concern is often just ensuring the capacitor is not under power or doesn’t have a stored charge–electrolytics […]
FAQ
Selecting and applying programmable power supplies
A system-level view of testing is helpful when specifying power requirements. Jeff Brakley • Ametek Programmable Power Inc. There are numerous options available for programmable dc power supplies. Users can select from a wide range of voltage, current, and power ratings. Other specifications include input voltage, output voltage regulation, output ripple and noise, and transient […]
Why won’t it work? A look at antiresonance
A clock generator generally consists of a resonant circuit and an amplifier. Resonance occurs in an electrical circuit when XL = XC. At this juncture, the imaginary component of the transfer function is zero. A resonant circuit oscillates at a specific frequency. Like certain other electrical phenomena, it is capable of generating higher voltages or […]
The basics of Kelvin connections
It is difficult to obtain highly accurate readings of current and voltage in small resistances. The difficulty exists both in analog as well as digital meters. Part of the reason is that their sensor wires and fine probe points add unknown amounts of resistance to the measurement, potentially more than that of the device under […]
Things to know about multimeters
For years, ohmmeters have been integrated into the electrician’s multimeter. This is convenient, because ohms and volt are the most-performed measurements. Also, only a single instrument must be purchased and maintained. Multimeters are further subdivided into ac, bench-type multimeters and hand-held, battery-powered multimeters. The hand-held instruments are more convenient. Most often just grab your handheld […]
What’s all this Helmholtz coil stuff?
The Helmholtz coil was not devised to create a magnetic field, but to cancel it. The Helmholtz coil actually consists of two identical circular air-core coils, large enough to contain the work under study. The coils are situated along a common axis that extends through the experimental area. The distance between the coils is equal […]
Sorting out balanced cables and differential signaling
Lines carrying symmetric signals, i.e. those with opposite polarities but with equal amplitudes on each line are commonly called balanced. But the correct term is differential signaling. While balanced lines and differential signaling may be used together, they are actually quite different. The key point that distinguished balanced lines from single-ended lines is that both […]
Analyzing jitter with an oscilloscope
Jitter–basically the deviation between true and measured periodicity–is harmful beyond a certain level. In measuring jitter, we are calculating RMS, peak-to-peak deviation or spectral density. Jitter at frequencies below 10 Hz is known as wander. High-frequency signals are more prone to jitter than low-frequency signals. The deviation in periodicity that constitutes jitter may be in […]
The difference between solar cells and LEDs
Perhaps thanks to YouTube, more people understand that light emitting diodes (LEDs) and solar cells may be thought of as mirror images of one another because the conversion of energy in each involves similar interactions of charge carriers. It’s easy to find YouTubers who have either created solar arrays from LEDs or rigged solar cells […]
The difference between impedance analyzers and network analyzers
At first glance, impedance analyzers and network analyzers seem to do the same thing: Describe the impedance of whatever is connected to their inputs. This statement is true as far as it goes, but as you might expect, there are significant differences between the two types of instruments. Here’s a review of the basics. There […]
