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Atlantic Alumina Company LLC (ATALCO), the only operating alumina refinery in the USA, has announced a partnership with the United States Department of War (DOW) and Concord Resources Holdings Ltd, in conjunction with Concord’s majority shareholder (a fund managed by commodities investment firm Pinnacle Asset Management L.P.), to sustain and increase domestic alumina production and establish the USA’s first large-scale primary gallium production circuit in Gramercy, Louisiana...

Enphase Energy Inc of Fremont, CA, USA (which supplies microinverter-based solar and battery systems) has begun production shipments of its IQ9N-3P Commercial Microinverter across the USA in late December. The product is manufactured in the USA to support domestic content requirements and Foreign Entity of Concern (FEOC) compliance for eligible commercial solar projects. This is Enphase’s first microinverter powered by gallium nitride (GaN) technology and designed for three-phase 480Y/277 V (wye) grid configurations, without using external transformers...

Accelerometers turn motion into measurable signals. From tilt and vibration to g-forces, they underpin countless designs. In this “Fun with Fundamentals” entry, we demystify their operation and take a quick look at the practical side of moving from datasheet to design.

From free fall to felt force: Accelerometer basics

Accelerometer is a device that measures the acceleration of an object relative to an observer in free fall. What it records is proper acceleration—the acceleration actually experienced—rather than coordinate acceleration, which is defined with respect to a chosen coordinate system that may itself be accelerating. Put simply, an accelerometer captures the acceleration felt by people and objects, the deviation from free fall that makes gravity and motion perceptible.

An accelerometer—also referred to as accelerometer sensor or acceleration sensor—operates by sensing changes in motion through the displacement of an internal proof mass. At its core, it’s an electromechanical device that measures acceleration forces. These forces can be static, like the constant pull of gravity, or dynamic, caused by movement or vibrations.

When the device experiences acceleration, this mass shifts relative to its housing, and the movement is converted into electrical signals. These signals are measured along one, two, or three axes, enabling detection of direction, vibration, and orientation. Gravity also acts on the proof mass, allowing the sensor to register tilt and position.

The electrical output is then amplified, filtered, and processed by internal circuitry before reaching a control system or processor. Once conditioned, the signal provides electronic systems with accurate data to monitor motion, detect vibration, and respond to variations in speed or direction across real-world applications.

In a nutshell, a typical accelerometer uses an electromechanical sensor to detect acceleration by tracking the displacement of an internal proof mass. When the device experiences either static acceleration—such as the constant pull of gravity—or dynamic acceleration—such as vibration, shock, or sudden impact—the proof mass shifts relative to its housing.

This movement alters the sensor’s electrical characteristics, producing a signal that is then amplified, filtered, and processed. The conditioned output allows electronic systems to quantify motion, distinguish between steady forces and abrupt changes, and respond accurately to variations in speed, orientation, or vibration.

Figure 1 Pencil rendering illustrates the suspended proof mass—the core sensing element—inside an accelerometer. Source: Author

The provided illustration hopefully serves as a useful conceptual model for an inertial accelerometer. It demonstrates the fundamental principle of inertial sensing, specifically showing how a suspended proof mass shifts in response to gravitational vectors and external acceleration. This mechanical displacement is the foundation for the capacitive or piezoresistive sensing used in modern MEMS devices to calculate precise changes in motion and orientation.

Accelerometer families and sensing principles

Moving to the common types of accelerometers, designs range from piezoelectric units that generate charge under mechanical stress—ideal for vibration and shock sensing but unable to register static acceleration—to piezoresistive devices that vary resistance with strain, enabling both static and low-frequency measurements.

Capacitive sensors detect proof-mass displacement through changing capacitance, a method that balances sensitivity with low power consumption and supports tilt and orientation detection. Triaxial versions extend these principles across three orthogonal axes, delivering full spatial motion data for navigation and vibration analysis.

MEMS accelerometers, meanwhile, miniaturize these mechanisms into silicon-based structures, integrating low-power circuitry with high precision, and now dominate both consumer electronics and industrial monitoring.

It’s worth noting that some advanced accelerometers depart from the classic proof-mass model, adopting optical or thermal sensing techniques instead. In thermal designs, a heated bubble of gas shifts within the sensor cavity under acceleration, and its displacement is tracked to infer orientation.

A representative example is the Memsic 2125 dual-axis accelerometer, which applies this thermal principle to deliver compact, low-power motion data. According to its datasheet, Memsic 2125 is a low-cost device capable of measuring tilt, collision, static and dynamic acceleration, rotation, and vibration, with a ±3 g range across two axes.

In practice, the core device—formally designated MXD2125 in Memsic datasheets and often referred to as Memsic 2125 in educational kits—employs a sealed gas chamber with a central heating element and four temperature sensors arranged around its perimeter. When the device is level, the heated gas pocket stabilizes at the chamber’s center, producing equal readings across all sensors.

Tilting or accelerating the device shifts the gas bubble toward specific sensors, creating measurable temperature differences. By comparing these values, the sensor resolves both static acceleration (gravity and tilt) and dynamic acceleration (motion such as vehicle travel). MXD2125 then translates the differential temperature data into pulse-duration signals, a format readily handled by microcontrollers for orientation and motion analysis.

Figure 2 Memsic 2125 module hosts the 2125 chip on a breakout PCB, exposing all I/O pins. Source: Parallax Inc.

A side note: the Memsic 2125 dual-axis thermal accelerometer is now obsolete, yet it remains a valuable reference point. Its distinctive thermal bubble principle—tracking the displacement of heated gas rather than a suspended proof mass—illustrates an alternative sensing approach that broadened the taxonomy of accelerometer designs.

The device’s simple pulse-duration output made it accessible in educational kits and embedded projects, ensuring its continued presence in documentation and hobbyist literature. I include it here because it underscores the historical branching of accelerometer technology prior to MEMS capacitive adoption.

Turning to the true mechanical force-balance accelerometer, recall that the classic mechanical accelerometer—often called a G-meter—embodies the elegance of direct inertial transduction. These instruments convert acceleration into deflection through mass-spring dynamics, a principle that long predates MEMS yet remains instructive.

The force-balance variant advances this idea by applying active servo feedback to restore the proof mass to equilibrium, delivering improved linearity, bandwidth, and stability across wide operating ranges. From cockpit gauges to rugged industrial monitors, such designs underscore that precision can be achieved through mechanical transduction refined by servo electronics—rather than relying solely on silicon MEMS.

Figure 3 The LTFB-160 true mechanical force-balance accelerometer achieves high dynamic range and stability by restoring its proof mass with servo feedback. Source: Lunitek

From sensitivity to power: Key specs in accelerometer selection

When selecting an accelerometer, makers and engineers must weigh a spectrum of performance parameters. Sensitivity and measurement range balance fine motion detection against tolerance for shock or dynamic loads. Output type (analog vs. digital) shapes interface and signal conditioning requirements, while resolution defines the smallest detectable change in acceleration.

Frequency response governs usable bandwidth, ensuring capture of low-frequency tilt or high-frequency vibration. Equally important are power demands, which dictate suitability for battery-operated devices versus mains-powered systems; low-power sensors extend portable lifetimes, while higher-draw devices may be justified in precision or high-speed contexts.

Supporting specifications—such as noise density, linearity, cross-axis sensitivity, and temperature stability—further determine fidelity in real-world environments. Taken together, these criteria guide selection, ensuring the chosen accelerometer aligns with both design intent and operational constraints.

Accelerometers in action: Translating fundamentals into real-world life

Although hiding significant complexities, accelerometers are not too distant from the hands of hobbyists and makers. Prewired and easily available accelerometer modules like ADXL345, MPU6050, or LIS3DH ease up breadboard experiments and enable quick thru-hole prototypes, while high-precision analog sensors like ADXL1002 enable a leap into advanced industrial vibration analysis.

Now it’s your turn—move your next step from fundamentals to practical applications, starting from handhelds and wearables to vehicles and machines, and extending further into robotics, drones, and predictive maintenance systems. Beyond engineering labs, accelerometers are already shaping households, medical devices, agriculture practices, security systems, and even structural monitoring, quietly embedding motion awareness into the fabric of everyday life.

So, pick up a module, wire it to your breadboard, and let motion sensing spark your next prototype—because accelerometers are waiting to translate your ideas into action.

T. K. Hareendran is a self-taught electronics enthusiast with a strong passion for innovative circuit design and hands-on technology. He develops both experimental and practical electronic projects, documenting and sharing his work to support fellow tinkerers and learners. Beyond the workbench, he dedicates time to technical writing and hardware evaluations to contribute meaningfully to the maker community.

Related Content

• A Guide to Accelerometer Specifications
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• Optimizing high precision tilt/angle sensing: Accelerometer fundamentals
• One accelerometer interrupt pin for both wakeup and non-motion detection

The post Fundamentals in motion: Accelerometers demystified appeared first on EDN.

How do single-pole wall switches work, and how can they fail? Read on for all the details.

Speaking of misbehaving power toggles, a few weeks back (as I’m writing this in mid-December), the kitchen wall switch that controls power going to our garbage disposal started flaking out. Flipping it to the “on” position sometimes still worked, as had reliably been the case previously, but other times didn’t.

Over only a few days’ time, the percentage of garbage disposal power-on failures increased to near-100%, although I found I could still coax it to fire up if I then pressed down firmly on the center of the switch. Clearly, it was time to visit the local Home Depot and buy-then-install a replacement. And then, because I’d never taken a wall switch apart before, it was teardown education time for me, using the original failed unit as my dissection candidate!

Diagnosing in the dark

As background, our home was originally built in the mid-1980s. We’re the third owners; we’ve never tried to track down the folks who originally built it, and who may or may not still be alive, but the second owner is definitely deceased. So, there’s really nobody we can turn to for answers to any residential electrical, plumbing, or other questions we have; we’re on our own.

Some of the wall switches scattered throughout the house are the traditional “toggle” style:

But many of them are the more modern decorator “rocker” design:

For example, here’s a Leviton Decora (which the company started selling way back in 1973, I learned while researching this piece) dual single-pole switch cluster in one of the bathrooms:

It looks just like the two-switch cluster originally in the kitchen, although you’ll have to take my word on this as I didn’t think to snap a photo until after replacing the misbehaving switch there.

In the cabinet underneath the sink is a dual AC outlet set. The bottom outlet is always “hot” and powers the dishwasher to the left of the sink. The top outlet (the one we particularly care about today) connects to the garbage disposal’s power cord and is controlled by the aforementioned wall switch. I also learned when visiting the circuit breaker box prior to doing the switch swap that the garbage disposal has its own dedicated breaker and electricity feed (which, it turns out, is a recommended and common approach).

A beefier successor

Even prior to removing the wall plate and extracting the failed switch, I had a sneaking suspicion it was a standard ~15A model like the one next to it, which controls the light above the sink. I theorized that this power handling spec shortcoming might explain its eventual failure, so I selected a heavier-duty 20A successor. Here’s the new switch’s packaging, beginning with the front panel (as usual, and as with successive photos, accompanied by a 0.75″/19.1 mm diameter U.S. penny for size comparison purposes). Note the claimed “Light Almond” color, which would seemingly match the two-switch cluster color you saw earlier. Hold that thought:

And here are the remainder of the box sides:

Installation instructions were printed on the inside of the box.

The only slight (and surprising) complication was that (as with the original) while the line and load connections were both still on one side, with ground on the other, the connection sides were swapped versus the original switch. After a bit of colorful language, I managed. Voila:

The remaining original switch on the left, again controlling the above-sink light, is “Light Almond” (or at least something close to that tint). The new one on the right, however, is not “Light Almond” as claimed (and no, I didn’t think to take a full set of photos before installing it, either; this is all I’ve got). And yes, I twitch inside every time I notice the disparity. Eventually, I’ll yank it back out of the wall and return it for a correct-color replacement. But for now, it works, and I’d like to take a break from further colorful language (or worse), so I just grin and bear it.

Analyzing an antique

As for the original, now-malfunctioning right-side switch, on the other hand…plenty of photos of that. Let’s start with some overview shots:

As I’d suspected, this was a conventional 15A-spec’d switch (at first, I’d thought it said 5A but the leading “1” is there, just faintly stamped):

Backside next:

Those two screws originally mounted the switch to the box that surrounded it. The replacement switch came with a brand-new set that I used for re-installation purposes instead:

Another set of marking closeups:

And now for the right side:

I have no clue what the brown goo is that’s deposited at the top, nor do I either want to know what it is or take any responsibility for it. Did I mention that we’re the third owners, and that this switch dated from the original construction 40+ years and two owners ago?

I’m guessing maybe this is what happens when you turn on the garbage disposal with hands still wet and sudsy from hand-washing dishes (or maybe those are food remnants)? Regardless, the goop didn’t seemingly seep down to the switch contacts, so although I originally suspected otherwise, I eventually concluded that it likely ended up not being the failure root cause.

The bottom’s thankfully more pristine:

Those upper and lower metal tabs, it turns out, are our pathway inside. Bend ‘em out:

And the rear black plastic piece pulls away straightaway:

Here’s a basic wall switch functional primer, as I’ve gathered from research on conceptually similar (albeit differing-implementation) Leviton Decora units dissected by others:

along with my own potentially flawed hypothesizing; reader feedback is as always welcomed in the comments!).

The front spring-augmented assembly, with the spring there to hold it in place in one of two possible positions, fits into the grooves of the larger of the two metal pieces in the rear assembly. Line current routes from the screw attached to the larger lower rear-assembly piece and to the front assembly through that same spring-assisted metal-to-metal press-together. And when the switch is in the “on” position, the current then further passes on to the smaller rear-assembly piece, and from there onward to the load via the other attached screw.

Snap, crackle, and pop

However, you’ve undoubtedly already noticed the significant degradation of the contact at the end of the front assembly, which you’ll see more clearly shortly. And if you peer inside the rear assembly, there’s similar degradation at the smaller “load” metal piece’s contact, too:

Let’s take a closer look; the two metal pieces pull right out of the black plastic surroundings:

Now for a couple of closeups of the smaller, degraded-contact piece (yes, that’s a piece of single-sided transparent adhesive tape holding the penny upright and in place!):

Zap

Next, let’s look at what it originally mated with when the toggle was in the “on” position:

Jeepers:

Another black plastic plate also thankfully detached absent any drama:

And where did all the scorched metal that got burned off both contacts end up? Coating the remainder of the assembly, that’s where, most of it toward the bottom (gravity, don’cha know):

Including all over the back of the switch plate itself, along with the surrounding frame:

Our garbage disposal is a 3/4 HP InSinkErator Badger 5XP, with a specified current draw of 9.5A. Note, however, that this is also documented as an “average load” rating; the surge current on motor turn-on, for example, is likely much higher, as well as not managed by any start capacitors inside the appliance, which would be first-time charging up in parallel in such a scenario (in contrast, by the way, the dishwasher next to it, a Kenmore 66513409N410, specs 8.1A of “total current”, again presumably average, and 1.2A of which is pulled by the motor). So, given that this was only a 15A switch, I’m surprised it lasted as long as it did. Agree or disagree, readers? Share your thoughts on this and anything else that caught your attention in the comments!

—Brian Dipert is the Principal at Sierra Media and a former technical editor at EDN Magazine, where he still regularly contributes as a freelancer.

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The post A failed switch in a wall plate = A garbage disposal that no longer masticates appeared first on EDN.

In a trading update for full-year 2025, epiwafer and substrate maker IQE plc of Cardiff, Wales, UK says it saw strong trading momentum in second-half 2025 due to faster-than- expected funding releases for some US military and defence programs, previously anticipated for 2026...