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Global industry association SEMI has joined the ReSiLient project consortium to help fortify Europe’s semiconductor ecosystem and advance global supply chain resilience. Kicking off in 2026, the project aims to tackle Europe’s critical dependence on imported silicon (Si) and silicon carbide (SiC) raw materials...

Components required: Breadboard (optional) 1× LM324N 4× 1kΩ Resistors 1× 220kΩ Potentiometer (to adjust reference voltage) 4× LEDs (I'm using random colours because this is a prototype) 1× 220Ω Resistor 5V Supply Earphone Jack (as an input) Some cables and staplers (used by me) Audio Amplifier* wiring diagrams will be posted here, or visit the link in the comment section ^-^ *Connect the input of the VU meter to an audio amplifier with separate power supply submitted by /u/Curious_Deal5981 [link] [comments]

PIN photodiode collects, counts, and discriminates alpha energies to determine residences’ radon gas-caused cancer danger degrees.

Back in late July, when I was working on last month’s published piece on radon gas analysis, I longed to see what was inside the battery-operated sensing device I’d recently started using.

But I resisted the temptation to fire up the spudger and screwdriver set, because:

• I’d bought it myself, for $100+, and
• I intended to continue using it long-term, since radon gas concentrations vary over time.

Even if I trusted my ability to disassemble it and then put it back together again in still-full-functional form (which I don’t), I didn’t want to interrupt the data-logging cadence even briefly.

But Providence seemingly intervened on my behalf, as counterbalance to my reticence. Less than a week after my post appeared, a PR contact from Chinese company X-Sense, who swore she hadn’t even seen my coverage yet, reached out to see if I was interested in reviewing its latest consumer-tailored smart radon alarm, the just-introduced XR0A-iR. The device is so new that it only showed up on the company website a few days ago, as I write this on September 10, 2026.

Spooky, eh?

I accepted the invitation with the as-usual qualifiers in such situations: that the company would not see my coverage until it appeared in publicly published form on EDN’s website, and that X-Sense would have no ability to influence the content either in-advance or post-publication. The PR contact agreed.

I also asked for two units; one for hands-on testing (for which I planned to recruit my next-door neighbor, both because he didn’t have one yet and because I wanted to get a non-techie’s take on activation and ongoing use) and the other to satisfy my own teardown curiosity.

Smart equals pervasive data access

X-Sense agreed again. And late last month, two units showed up at my front door. My next-door neighbor successfully activated his yesterday; stay tuned for his hands-on observations to come in a future post. And that same (yester)day, I took the other one apart.

X-Sense is a smart home device manufacturer of which I wasn’t previously aware. The company’s products are analogous to those (for example) of TP-Link, whose Kasa and Tapo temperature, humidity and fluid leak sensors I’ve dissected in recent months. X-Sense already had two radon sensors in its product portfolio, the XR0A-SR and higher-end XR0B-SR, but they’re standalone-use units. The XR0A-iR is its first “connected” radon-related product.

I’ll as-usual start with some outer box shots, accompanied by a 0.75″ (19.1 mm) diameter U.S. penny for size comparison purposes. Top.

Front.

Left side.

Back.

Right side.

And bottom.

Packet secrets

The first thing you’ll see after removing the box lid is a comprehensive and consumer-comprehensible (those adjectives rarely get used together, in a positive sense, at least!) user guide.

Underneath it is our patient.

Surrounded by two mysterious baggies.

I jest; they’re not mysterious, because they’re labeled. One, containing silica gel, I commonly encounter to absorb humidity, thereby keeping the electronics dry. The other, marked as indicating that inside it was activated charcoal, was a bit more of an initial head-scratcher.

But then I recalled the mail-in radon lab test (mentioned in my prior writeup) that my wife and I ordered prior to purchasing our home a decade-plus ago, and which looked something like this.

I rattle sound-suspected at the time, and subsequent research has confirmed, that inside it was activated charcoal, used both for short-duration testing and (interestingly, at least to me) for filtering radon out of well water. That said, it’s not recommended for ongoing residential-air radon gas cleansing purposes. Here, I’m guessing, it absorbs ambient radon gas at warehouses and retailer shelves that would otherwise end up on the device’s sensor, adversely affecting subsequent initial-powerup measurement results in the process.

Onward. Here’s our patient, now freed from its previous cardboard captivity. Top (note the grille; hold that thought).

Front.

Left side (note the vents).

Back.

Right (ditto).

And bottom.

Before beginning the dissection, here’s an obligatory company-supplied conceptual image of the supposed “guts”, that I know you all love so much (me too).

The battery compartment often effectively does double-duty as the pathway inside the device. Let’s see if it pans out again.

Those four screw heads, one at each corner, look promising. The unit specs a 2-year (and user-replaceable) battery life claim, by the way. Not too shabby!

Before proceeding, though, let’s zoom in on the always-informative FCC ID (2AU4DDDM).

And now for those pesky screws.

(Non-)adhesive (non-)impediments

Ladies and gentlemen, we’ve hit the jackpot!

Those white glue deposits at both flex cable-to-connector junctions initially gave me pause. Was I not going to be able to keep this teardown non-destructive, always my preference?

Not so “gluey” after all, it turned out. Never mind. Keep calm and carry on.

Let’s focus our attention first on the top panel and interior of the upper enclosure.

Four more visible screw heads suggest a way to detach the former from the latter. Let’s see.

Bingo!

And now for another perspective, after flipping the enclosure over.

Setting the top panel aside for the moment, we now see that two more screws hold the display assembly in place.

You know what comes next.

And there she goes.

Removing four more screws, I’m betting, will give us a glimpse of the display backside.

I’m on a roll! It’s usually at about this time of inflated self-confidence, by the way, when I short out something, or cut myself and bleed all over everything. Consider yourself warned.

This is not the ventilation grill you’re looking for

Now for the top panel, and maybe the most baffling aspect of this design. Look back at the earlier top-side overview shot, and you’ll see what appears to be a grille. We already know from the box-bottom notations that this is a passive diffusion design; no (noisy and battery-draining) fans, only natural airflow through the device. Does it flow through the top?

The fact that the documentation only notates the earlier-seen enclosure side vents as “air intake areas” is head-scratching. And when you look at the grille from the inside, you see a black piece of plastic nearly completely covering it. So “nope” is apparently the answer to my question.

So, then, why is it here at all? The earlier-mentioned high-end standalone XR0B-SR model has a speaker up top and behind the grill, for audible-alert purposes.

But it’s also got buttons up top, versus in the front with this particular model, so it’s not like X-Sense can reuse any particular assemblage piece across multiple models.

My only other possible conclusion is that the company is striving to establish a common cosmetic “look” across all models. To wit, ironically, I suspect that the purpose of that black plastic piece is to prevent ambient airflow from going in and/or out the top, forcing it to instead route from one side to the other, presumably over the sensor in the process. Other reader ideas are welcomed in the comments!

Speaking of which, that varying black foam-and-shiny silver plastic circular region up top, held in place by an also-plastic brace, looks promising as a potential radon sensor location.

Let’s see what’s inside it, after first perusing other varying-location perspectives of the overall internal assemblage. Front.

Left side.

Back.

And right side.

Sensing insights

I’ve delayed entry, thereby building suspense, more than enough at this point. Here goes nothing.

This looks promising.

We’ve hit pay dirt (although a subsequent Google search on the “CD2026MAR6729” mark wasn’t, alas, even remotely fruitful)!

Upside-down temporary reinsertion into the cavity affords us a closer perspective.

Again, referencing the bottom packaging information, which described the unit’s measurement method as “continuous alpha spectrometry”, this is, I believe (readers?) a solid-state PIN photodiode, described along with other possible implementation approaches in a useful online reference that I came across during my research.

As the acronym suggests, the heavily doped p-type and n-type semiconductor regions, used (among other things) as ohmic contacts, are separated by an intermediary un-doped intrinsic semiconductor region.

The conceptual visual similarity with a multi-pixel image sensor is likely already obvious.

In this case, however, where (i.e. in a particular x:y pixel grid coordinate combination) an alpha particle has struck the semiconductor medium isn’t relevant; that one has struck is all that’s necessary to determine. The sensor normally points downward; the surrounding plastic is obviously no functional impediment. In the following photo, I put the assembly back together so you can see the routing of the seeming single-wire (surprisingly, at least to me) harness out of it.

PCB details

We still haven’t found the system’s intelligence and wireless connectivity, however. The prior internal assembly front view image suggests there’s a PCB underneath the sensor. Let’s see.

Here it is.

Let’s next see what’s underneath that shiny plastic cover.

A mess of passives (along with a few five-lead ICs, likely single-package dual-transistor devices) is admittedly not what I expected to find. Then again, as I’ve confessed plenty of times before, analog is admittedly not my area of particular expertise.

Two more screws to go.

And the comparatively boring PCB backside is now accessible for visual perusal.

Yawn…unless you’re into switches, test points and/or battery terminals, that is. Let’s give the PCB frontside one more now-standalone look.

The combo 2.4 GHz Wi-Fi plus Bluetooth LE module at left, with a common-frequency, combo-protocol antenna sticking out of it, is the Ai-WB2-32S kit from a previously-unknown-to-me company called AI-Thinker. Is there something explicitly AI-related to this particular product (and/or the manufacturer, more generally)? Or is it just one of those cases nowadays where anything sounds more important if you tack “AI” onto it? The under-Faraday-Cage photo published at the webpage is woefully low-res, but hey, there’s also a spec sheet.

And at center is the system’s processing nexus, the 32-bit Arm Cortex M4-based N32L406MBL7 microcontroller from another new-to-me supplier, Nations Technologies. It has onboard flash memory and SRAM, thereby explaining why I don’t see any discrete memories on the PCB.

Last, but not least, after carefully putting everything back together, the device fired right up.

It’s a miracle!

That’s a wrap for today, folks. As always, reader insights are welcomed in the comments!

—Brian Dipert is the associate editor, as well as a contributing editor, at EDN.

Related Content

• Radon: Level detection, risk determination, and as-needed mitigation
• Improve HVAC efficiency with accurate sensors
• My Geiger counter doesn’t count (sob sob)
• Design femtoampere circuits with low leakage, part 1 and part 2

The post Radon sensor embeds sizeable alpha particle detector appeared first on EDN.

India’s rapidly expanding network of electric-vehicle chargers still faces a host of technical and deployment challenges. According to one recent report, a significant gap remains between the infrastructure currently available and the charging stations that could be needed as EV adoption increases. The challenges with the charging infrastructure extend beyond simply increasing the number of chargers and include charger reliability, power capacity, grid connectivity and technical standardisation.

Non-Functional EV Chargers Highlight Reliability Challenge

Some common issues include non-operational chargers. EV chargers can be installed but become non-operational or unavailable due to communication issues, power failures, equipment failures, and poor maintenance. To maximise charger uptime, real-time monitoring, diagnostics, remote fault detection and maintenance are needed.

India Needs More Heavy-Duty and Highway Charging

The charging requirements of electric cars, buses and commercial vehicles all differ.​ Heavy-duty electric vehicles, in particular, will need high-power charging systems that can deliver a lot of energy in a short period of time, making high-powered chargers, grid connections, thermal management and power-electronics systems critical areas for research and development.

Standardisation Can Improve EV Charging Compatibility

Another important challenge is the technical inconsistency of the implementations of charge points on the market. Standardised communication protocols, connector types, charging profiles and interoperability requirements can enable chargers to work more harmoniously with different EVs and charge networks.

The charging ecosystem can be further optimised through the use of smart charging technologies. Load management, real-time load monitoring, dynamic power distribution and solar integration can enable chargers to make more efficient use of available grid capacity.

The post Why India Needs Smarter and More Standardised EV Charging Infrastructure appeared first on ELE Times.

India is exploring new electric-motor technologies that may help the electric vehicle (EV) industry reduce reliance on rare-earth permanent magnets. During the recent New Delhi deep-tech showcase, Indian innovators introduced a rare-earth-free electric powertrain, reflecting the country’s growing focus on developing alternative motor technologies free of rare-earth materials.

Chara Technologies, which is based in Bengaluru, was among the companies showcased. The company has built rare-earth-free synchronous reluctance motors and controllers for electric mobility. It uses materials that are indigenously sourceable materials and does not require rare-earth permanent magnets, which are commonly used in many high-performance electric motors. Chara’s motor platform covers 8 kW-30 kW, and the products are ARAI- and ICAT-certified.

Why Rare-Earth-Free Motors Matter for EVs

India currently imports all of its downstream sintered NdFeB rare-earth permanent magnet demand. These high-efficiency magnets are preferred in electric vehicle motors due to their high magnetic properties, which support compact and high-power density motor designs. Although India has some large deposits of rare-earth minerals, as with many other processing countries, India is not yet equipped with industrial-scale midstream facilities to convert rare-earth oxides into metals, alloys, and magnets and is therefore reliant on imports of sintered NdFeB magnets.

India’s Push for Alternative EV Motor Technology

India’s EV manufacturers could reduce reliance on imported rare-earth magnet supply chains by adopting rare-earth-free motors, which can enable greater use of locally sourceable materials and manufacturing capabilities. However, these motors will be commercially successful only if they offer comparable or better efficiency, power density, cost, thermal performance, reliability and scalability.

The post Rare-Earth-Free EV Motors: How India Could Reduce Dependence on Critical Magnet Materials appeared first on ELE Times.

India is moving toward higher domestic manufacturing of key electric-vehicle drivetrain components that deliver mechanical power from the electric motor to the driving wheels. The Ministry of Heavy Industries (MHI) has strengthened localisation requirements for EV buses and trucks under the PM Electric Drive Revolution in Innovation Vehicle Enhancement (PM E-DRIVE) initiative.

The new amendments under Phased Manufacturing Programme (PMP) for M2/M3 e-buses and N2/N3 e-trucks will ensure higher local manufacturing of traction, motor controllers and other powertrain-related components from September 1, 2026.

Localisation requirements will also extend to traction-motor controllers, including inverters, from April 1, 2027. The revised requirements include domestic assembly of electronic components, semiconductor devices and connectors directly on printed circuit boards, along with the fitment of high-voltage connectors, cables, heat sinks, enclosures, and software or firmware flashing.

India wants EV manufacturers to source more components locally. However, many traction motors use rare-earth magnets, for which India depends significantly on imports. Export restrictions have disrupted the supply of these magnets. Therefore, SIAM asked the government to extend the September 1, 2026, localisation deadline.

The post India Tightens EV Localisation Rules, Putting Traction Motor Technology in Focus appeared first on ELE Times.

To strengthen the security of military drones and identify hidden security such as hidden software threats and potential cyber vulnerabilities (specifically of Chinese origin), India Army has established a dedicated laboratory in New Delhi. Named AASHVAST (Assessment and Analysis of Electronic Systems Hardware for Vulnerabilities and Security Threats), the laboratory was inaugurated by the chief of Army Staff, General Dhiraj Seth at the Directorate General of Electronics and Mechanical Engineering (DG EME) premises in Delhi Cantonment on August 14, 2026.

The lab is designed to scan, analyse, and assess military drones to identify hidden security threats by examining both the hardware and software systems of military drones. The lab can help identify security risks that conventional physical inspections may not reveal. It can scan for hidden passwords, embedded encryption keys, remote-access tools, unauthorised command pathways and other vulnerabilities that could potentially be exploited to compromise unmanned aircraft.

An important aspect of AASHVAST is the air-gapped and read-only operating environment which enables the software and firmware to be examined without connecting the system to an external network or making any changes to the hardware under assessment. Technicians and authorised officers receive a consolidated view of the identified risk after vulnerabilities are ranked by severity and converted into a structured security assessment.

The post Indian Army Launches AASHVAST Lab to Detect Chinese Components and Cyber Threats appeared first on ELE Times.

AeroVironment announced that it received the first international order for its LOCUST High-Energy Laser Counter-Unmanned Aircraft Systems for over $50 million and that it will supply a number of systems with support, which, according to the company, is “an enabling milestone in the international adoption of directed-energy air defence”. LOCUST combines sensors, tracking and laser defeat against group 1-3 Unmanned Aircraft Systems and other airborne targets. It can be implemented in a fixed, palletized, or mobile configuration and integrated with a wide range of available external sensors and command-and control networks.

A single shot with a LOCUST engagement could cost AeroVironment under $10. That alone presents a huge advantage for laser against cheap, widely produced drones, since air-defence missiles could end up costing much more than the drone. Additionally, there are no traditional interceptor reload limitations on laser weapons-though their performance will still vary by availability of power, conditions, range, and visibility and the world order is adopting AeroVironment’s choice in a $464.8 million contract with the U.S. Army for high-energy laser production, and has ordered over $30 million in new investments in their Albuquerque campus facility, in an environment increasingly calling for layered counter-drone defences.

The post AeroVironment Receives First International Order for LOCUST Laser System appeared first on ELE Times.

US defence firm Covenant has unveiled its Anthem, a ground-launched cruise missile capable of carrying a heavy payload with low unit cost high volume manufacturing. The missile is designed to have over 200kg pay load, and the system is designed to complement established long-range weapons such as Tomahawk and JASSM-ER. Anthem utilizes a solid rocket booster during the boost phase, with a heavy fuel jet engine used during cruise. Covenant states the missile underwent more than 200 flights prior to the unveiling; The firm is aiming at a price of between mid- and high-six digits per missile when in full production.

Manufacturing capacity is the focus of the program, and Covenant has opened up a new 105,00-sqft facility in Dallas intended to build up to 5,000 missiles a year, and is planning an equivalently sized, equivalent-capacity facility in Germany along with an Israeli facility planned to build up to 2,000 units a year. It is estimated Covenant has about $150 million in orders and plans to increase production through 2027. The company has chosen a number of rocket-motor manufacturers and pre-signed thousand-unit long-term contracts for jet engines as a remedy for this bottleneck. Its example is indicative of a broader defence industry trend towards low-cost smart weapons built using scalable commercial manufacturing.

The post Covenant Introduces a Mass-Produced Cruise Missile Called Anthem appeared first on ELE Times.

India is developing its directed energy capability through the Defence Research and Development Organization (DRDO). By utilizing SHIELD and the S-band High-Power Microwave Integrated Evaluation System for Lethality and Damage, DRDO has invited Indian industry to build the platform through the Defence Technology Development Funds program. SHIELD is not a usable weapon system, but an evaluation system that should subject electronics to a controlled amount of high-powered microwave energy and determine the extent of disruption, impairment, or damage.

This capability is of obvious interest to countering UAV’s, as each can have its own controller, navigation device, communication link, sensors, processor, etc. Focusing electromagnetic energy could have a catastrophic impact on these, without actually needing to hit each UAV with a bullet or missile; although this can only really ever prove a cheaper, faster response at very large scale against a large, cheaply produced fleet of UAV’s.

The program can also allow engineers to design friendly equipment that is safe from electromagnetic attack. Test data can lead to the creation of hardened enclosures, shielded cables and connectors, and reliable electronics power sources and ground components. Working with start-up firms and small, medium, and large businesses, the SHIELD project can build a strong indigenous Indian base in high-power microwave technology, EM testing, and electronic warfare that provides an essential platform for both offensive anti-drone weapons and protective electronics.

The post The DRDO’s SHIELD Programme Focused on Microwave & Drone-Electronics Testing appeared first on ELE Times.

The DAC (Defence Acquisition Council) of India approved, to the tune of approx. 1.10 lakh crore across the Army, Navy, and Air Force for procurement under their category, where about 98% of the approval would be for the Indian sector to strengthen the Indian Defence Manufacturing sector in this area. All sorts of platforms and electronic devices are approved under the following purchase categories. Army requires CBRN reconnaissance vehicles, high-mobility vehicles, mechanical Mine layers, ALHs, trawl tanks, and the SARVTRA bridge systems.

The council approved Arudhra radars for the Navy; the indigenous marine gas turbine’s design, development, and subsequent procurement would reduce dependence on foreign vendors and give India greater powers in warship production and maintenance. As for the Air Force proposals, they include a Ground-Based Multi-Purpose Jammer which “will counter adversary radars”; the RFID-based Defence Forces Secure Access Card is another feature that “replaces several documents like identity card, permits. The Acceptance of Necessity can be thought of as an initial clearance to procurement and not a signed contract. Yet the entire package spells out a huge opportunity in terms of radar, electronic warfare, RFID, propulsion, aerospace, and special vehicles supply.

The post 1.10 Lakh Crore Indian Defence Technology Pipeline Approved appeared first on ELE Times.

India is now helping Sri Lanka set up an artificial intelligence laboratory for its Army, making cutting-edge digital technologies a key focus of defence ties. The plan was rolled out by Defence Minister Rajnath Sing during his Colombo visit, during which three other pacts related to defence were signed between the two sides. The laboratory’s functions haven’t been specified yet, but this could include analysis of military data, support for surveillance tasks, logistics and resource management, and quicker planning-all critical elements for operations, officials indicated. The move indicates a trend towards leveraging AI as it has become easier for armies to gain a better grasp of the situations and make effective use of intelligence, data collected through sensors or surveillance equipment.

The agreements also include modernization of the L-70 air-defence guns utilized by the Sri Lanka Air Force and cooperation between the National Cadets Corps and the National Defence Colleges of both countries. Furthermore, India also provided spares for the Mk-II radar, some naval parts, and inflatable targets for training purposes. It indicates the extension of India’s regional defence partnership from traditional hardware and training to AI, digital infrastructure, and know-how exchange. Also, it may offer some new space for India’s defence-electronics firms specializing in sensors, secure communication systems, analytic software, and command and control.

The post India Will Open AI Labs for Sri Lankan Army appeared first on ELE Times.

When enclosure size and airflow constraints limit traditional bass‑reflex designs, passive radiators offer a smarter path to deep, controlled low‑frequency performance.

Audio engineers face a persistent challenge—delivering deep bass extension in compact, space‑constrained enclosures without resorting to unwieldy ports that introduce turbulence and design compromises. 

To address this, many have shifted from traditional bass‑reflex systems toward passive radiator (drone cone) topologies, which replace long ports with diaphragm‑based tuning elements that achieve low‑frequency response more efficiently.

This post will explore the mechanics of passive radiators, weigh their trade‑offs, and outline how to select the right approach for your next build.

How passive radiators work

At the heart of any passive radiator system lies the active driver, the true motor of the enclosure, converting amplifier power into acoustic energy. Its displacement dictates how much air is moved inside the box, setting the stage for low‑frequency behaviour.

Opposite to it sits the passive radiator—the drone cone—which visually resembles a standard loudspeaker but omits the voice coil and magnet. Instead, it functions as a mass‑loaded resonator: the trapped air volume inside the enclosure acts like a spring, driving the radiator in sympathy with the active driver’s motion to extend bass response without the turbulence of long ports.

Passive radiator vs. ported designs

When engineers weigh passive radiators against traditional bass‑reflex ports, the trade‑offs become clear. Passive radiators enable more compact enclosures by eliminating the need for long, tuned ports, and they completely sidestep the issue of turbulent airflow and audible chuffing at high excursions.

Their response carries a perceptibly steeper roll-off below tuning due to the compliance notch at the radiator’s free-air resonance, demanding careful tuning and mass adjustment to achieve the desired performance. By contrast, ported designs typically require larger internal volume to accommodate the port and maintain smooth airflow, and while they risk turbulence at higher levels, their fourth‑order roll‑off often produces a more gradual, natural decay.

Ports are also simpler to implement, relying on standard tubing or slot dimensions, whereas passive radiators introduce greater design complexity but reward it with noise‑free operation and space efficiency. In practice, when a purpose‑built speaker is paired with a matching passive radiator, its low‑frequency performance can extend nearly an octave deeper—delivering exceptional bass response without the added space or turbulence of a tuned vent.

Figure 1 A comparison of bass roll‑off profiles shows the passive radiator dropping more sharply (~30 dB/octave) below tuning than the ported system (~24 dB/octave). It explain that the radiator’s steeper slope comes from the acoustic notch at free‑air resonance, while both remain 4th‑order high‑pass alignments in theory. Source: Author

Critical design considerations for builders

Designing with passive radiators demands careful attention to tuning and balance. The system’s tuning frequency can be adjusted by adding or subtracting weight from the radiator’s cone, a straightforward but crucial step in aligning low‑frequency response with the enclosure’s goals.

Many builders refine this further by attaching extra mass directly to the cone, a technique that shifts the resonance frequency with precision and allows deeper bass extension without altering cabinet dimensions—though care must be taken to avoid over‑loading the driver and reducing efficiency.

Figure 2 A passive radiator with an easily adjustable mass enables the design of extremely compact speaker systems capable of incredibly low-frequency output. Source: Dayton Audio

Equally important is the volume compliance ratio (δ), where the passive radiator’s displacement volume should be 1.5 to 2 times greater than that of the active driver, ensuring efficient energy transfer and preventing the radiator from bottoming out. Finally, builders often employ dual passive radiators mounted on opposing sides of the cabinet, a technique that cancels mechanical reaction forces and stabilizes the enclosure. This vibration‑cancellation approach has become especially popular in portable Bluetooth speakers, where compact form factors and mechanical stability are paramount.

Chamber considerations

Every passive radiator system relies on the enclosure chamber as the “spring” that drives the radiator. The trapped air volume inside the cabinet provides the restoring force, so the chamber size must be carefully matched to the driver and radiator parameters. Too small a chamber can raise the tuning frequency and limit bass extension, while too large a chamber can reduce control and efficiency.

In practice, builders balance chamber volume against radiator size and mass, ensuring the compliance of the air spring complements the driver’s displacement. This makes chamber design just as critical as cone mass or compliance ratio when aiming for clean, extended low‑frequency performance.

At its core, the passive radiator system is simply another expression of the Helmholtz resonator principle. In a ported design, the mass of air in the port oscillates against the compliance of the chamber air, producing resonance at the tuned frequency.

With a passive radiator, the cone itself replaces the air column, acting as the moving mass while the trapped air in the enclosure remains the spring. This substitution preserves the Helmholtz effect but eliminates turbulent airflow, enabling deeper bass extension in compact cabinets without the drawbacks of long ports (port tubes).

Figure 3 Large-diameter port tubes optimize bass response in the active resonator circuit but increase enclosure volume and introduce air-chuffing distortions that passive radiators inherently avoid. Source: Author

Additional considerations

Beyond the fundamentals, builders should also weigh practical details that shape real‑world performance. Passive radiators generally require greater displacement capacity than the active driver—typically 1.5 to 2 times more—to move sufficient air at low frequencies and avoid bottoming out under load. Excursion limits are equally critical, since radiators can lose control if driven beyond their mechanical capacity.

Designers also watch for unwanted resonance peaks in the mid‑band, often around 1–2 kHz, which can be tamed with damping materials or improved suspension structures. Unlike ports, radiators don’t provide airflow cooling for the driver, so thermal management becomes a factor in high‑power systems. Finally, measurement and simulation tools such as impedance sweeps or modelling software are invaluable for predicting system behavior and ensuring the radiator is properly matched to the enclosure.

Also, accurate parameter testing is vital when integrating passive radiators. What’s more, builders can rely on impedance sweeps, frequency response plots, and excursion measurements to confirm tuning and displacement margins. These tests not only verify that the radiator achieves its intended resonance without bottoming out, but they also expose mid‑band anomalies or thermal limitations. While simulation tools provide useful predictions, hands‑on measurement remains the most reliable way to validate radiator behavior in a real enclosure.

Figure 4 A datasheet snippet outlines the key technical specifications for the passive radiator. Source: PUIaudio

Material choices for passive radiators

The diaphragm material defines how a passive radiator behaves under load. Rubber and elastomer membranes dominate portable designs, offering flexibility, damping, and resistance to moisture. Polymer composites such as ABS or PET provide lightweight stiffness and cost‑effective molding, though they can fatigue under high SPL.

Metal plates—aluminum or steel—deliver precise mass and long‑term stability but add weight and require damping to avoid ringing. Hybrid laminates that combine rubber with metal or fiber composites balance compliance with rigidity, giving engineers a tuneable middle ground. Selecting the right material is ultimately a trade‑off between durability, acoustic control, and the enclosure’s performance goals.

Application matrix

Choosing between a passive radiator and a ported design depends on the priorities of the build. Passive radiators excel in ultra‑compact or battery‑powered Bluetooth speakers, where enclosure space is at a premium and port tubes would be impractically long. They are also favored in subwoofers that demand deep extension without sacrificing internal volume, and in applications where eliminating port turbulence or chuffing is critical.

Ported designs, on the other hand, remain the go‑to for high‑power, high‑SPL systems such as PA speakers, as well as budget‑focused projects where standardized tubing makes tuning straightforward. When enclosure size is not a limiting factor, ports offer a simple, effective solution with predictable performance.

Passive radiators and ported bass‑reflex designs each bring their own strengths to the table—radiators deliver compactness, vibration control, and noise‑free operation, while ports offer simplicity, predictable tuning, and gradual roll‑off at the expense of larger enclosures and potential turbulence. The decision ultimately rests on your design priorities: whether you value space efficiency and acoustic precision, or raw output and ease of implementation.

As you move forward with your projects, think about which trade‑offs align best with your goals. Are you crafting a portable Bluetooth speaker that demands stability and compactness, or a high‑SPL system where simplicity and sheer output dominate? Share your builds and design choices—I’d love to hear how you’re pushing bass performance beyond the port.

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.

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• Liquid cooling fundamentals for high-power electronics

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Heya everyone! I'm Berry a cutesy trans gal! and I created a simple galvanic electrolysis machine from scratch ✨ It runs on a 5V USB power supply (smartphone/power bank/usb brick) , steps up to 30V, and limits current to a safe range (0.13–1.13mA). The total cost of this final interation works out around to roughly less than ₹600 or under $7 Quick specs :3 • Power: 5V USB → XL6009 → 30V • Current range: 0.13–1.13mA (I usually use 0.4–0.6mA) • It uses an LM324 , two 2N2222 , a few resistors, capacitors and two pots! • if built on breadboard then no soldering required Made from really few electronic components ✨ You can check out the whole document about it with the link here https://drive.google.com/drive/folders/1Q0zdHmhQ3L9I2UA0SnqAUSbfd it includes , schematic, parts list, build guide and more!! I also diy-ed the probe holder , and ermm the needle! but that's another thing on itself and not something I would recommend but yeah! I do have a design for a diy probe holder for commercial needles though if anyone is interested in that! If anyone has any questions then feel free to ask them 🫶✨ Edit:- yes i've tried it on myself!! And treated 65+ follicles in my second time using the machine on myself \^\^ r/diyelectrolysis https://cdn.imgchest.com/files/597c77d60eee.jpg [Schematic](https://cdn.imgchest.com/files/3bd2baf37d40.jpg) submitted by /u/BlueberryCultural361 [link] [comments]

Олександр Чорний (05.12.1989 – 13.03.2022) kpi сб, 09/12/2026 - 21:04

💎 Набір до команди «Формула Студент КПІ» kpi сб, 09/12/2026 - 20:49

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