Tag: Electronics

Exploring the Evolution of Inflight Entertainment: The Forgotten eXport Connector | September 14 2025, 13:24

We’re taking off. I’m wondering what kind of connector this is. Googling it. About 10 years ago, the Panasonic IFE multimedia system (which seems to have been used on B773ER and A333, I’m on a Boeing 777ER) featured a new port named eXport. It was a 9-pin mini-DIN connector for iPods. You could buy an adapter cable made by Griffin that essentially served as a bridge between the 9-pin mini-DIN and the 30-pin dock connector of iPods. Do you remember such connectors on iPods? And do you remember iPods at all? This cable allowed you to charge the iPod, control it via the IFE system, and transmit media from it to the IFE system. Time flies so fast. Looked up when the airplane was made – 14 years ago. That is, 14 years ago it still made sense to integrate a proprietary connector into the seats that essentially worked only with iPods.

I’m not even writing about RJ-45 above. White-orange orange, white-green blue, white-blue green, white-brown brown

Update from a page that has been gone for ten years, but the archive org remembers everything

And how does all this work? Here are some visual materials for clarity and facts from Panasonic (…about the biggest and highest-flying accessory for iPod in the world (as someone from Apple put it)

1. Allows audio and video signals to be transmitted from a passenger’s iPod to the IFE system, while also providing power and charging the iPod.

2. The eXport solution consists of two main components: the eXport connector (installed in the seat) and the eXport cable (connects the iPod to the eXport connector).

3. The crew will provide the eXport cable to passengers during the flight.

4. The solution is the world’s first Apple-certified Made for iPod” and Made for iPhone” solution, specifically designed for commercial airliners.

5. Natively supports Apple authentication technology.

6. In the near future, Panasonic will introduce additional functionality that will allow two-way communication between the iPod and the IFE system.

7. Supports both iPod and iPhone (in airplane mode”).

The reason a special cable is needed is that Apple does not allow video to be transmitted via USB. The only alternative would be to have three RCA connectors and an AC power socket onboard. But it’s expensive (installing an AC power system) and not worth the extra weight. Plus, it takes up legroom under the seat. Moreover, having three RCA connectors is a lot of ‘ports’ (red, yellow, white), which can confuse passengers (imagine a night flight in a darkened cabin). It only increases the workload on the crew, who are responsible for safety and comfort, not tech support.”

Exploring Airport Security: How Baggage Scanners Work | September 02 2025, 20:29

The day after tomorrow, I am flying to Amsterdam (and then to Turkey), and I remembered that I had an unanswered question to myself about how baggage scanners work at the airport. Of course, I knew that it was essentially computer tomography, X-rays and all that, but I wanted more details. And below is the response as to why they ask you to take out water, and why sometimes they do not.

It turns out that modern scanners can not only see the shape of objects but also determine what material they are made of. How does a regular scanner work? Dense materials (such as metal) absorb a lot of radiation and appear bright or opaque in images. Less dense materials absorb little radiation and appear dark. Hence laptops, for example, had to be taken out — not because the scanner couldn’t recognize them, but because their dense components (battery, boards) could be used to hide other prohibited items behind them. So, it has long been not just scanners, but computer tomography — in essence, the bag or suitcase is scanned from all sides, then a 3D image is created. It seems like everyone knows this.

But I mentioned that they understand the materials items are made from. How?

It turns out that the scanner uses dual-energy X-ray technology. It scans the object with two beams of rays of different energy levels (high and low). Since materials absorb radiation differently depending on the energy of the ray and their atomic composition, the system analyzes this difference. Based on the absorption ratio of the two beams, the effective atomic number Z — a key characteristic, a kind of “elemental fingerprint” of the substance, is calculated.

The problem is that this “fingerprint” of water (~7.4) and many explosives are almost identical. This is precisely why water was banned. Relying only on this parameter would mean receiving a huge number of false alarms.

Here is where computer tomography (CT) comes into play. The scanner creates an accurate three-dimensional (3D) model of the contents of the bag. From the 3D model, the system obtains the exact volume (V) of each object. Based on data on the absorption of X-rays, its mass (m) is calculated. Then it’s simple: ρ=m/V.

That is, the system does not make a decision based on one parameter. It plots each detected substance on a two-dimensional graph with axes “Z — density.” On this graph, water and explosives, having almost the same atomic number, occupy completely different positions due to different densities.

And that’s precisely why water can sometimes be carried through. Smart machines simply do not mark it as something significant, but still identify it as water. Then procedures follow. If the airport has updated the machines, but not the procedures, they will ask to dispose of the water. But also, not all machines are updated everywhere, and at the same airport, it depends on which line is open at the moment.

The cost of such a scanner is $300-400 thousand.

The scanners for people work differently. They use millimeter waves. They pass through clothing and reflect back from the skin. Water absorbs them significantly, so they penetrate only a couple of millimeters. The system registers the reflected signal and constructs a three-dimensional map of the body surface and objects under the clothing. But it does not show this — instead, it displays a simplified contour of a person and shows on it what ML found unusual. Therefore, by the way, many try to carry various items inside themselves, knowing that such a scanner absolutely cannot see it.

Inside Apple AirPods: Design, Battery, and Antenna Secrets Revealed | August 23 2025, 01:52

Very interesting video about how Apple Airpods headphones work (in the comments). You can read about it, or you can just like this post and go check out the original video in the comments. It has pictures!

Battery. 6 hours of operation, but the capacity is only 2% of the iPhone battery capacity. “Dead zones” in the battery, which lead to reduced operating time, can occur due to sudden temperature changes or even just dropping the headphones on the floor. There is a very dense “layered cake” made from a couple dozen layers of anode-cathode. Batteries of fake AirPods or cheap analogs are much worse. Physics: Poor packaging means less active material and fewer lithium ions moving with each cycle => reduced energy density and increased internal resistance => more energy is lost as heat => battery wears out faster.

Antenna. It is located in the stem because the human head significantly dampens the signal. But there is little space in the stem. Metal strip antenna, size 2 mm by 10 microns(!). That’s thinner than human hair. At such size, it cannot maintain shape on its own. In other consumer electronics, antennas can be etched on the printed circuit board, but this limits them to two dimensions. For the AirPod stem, there isn’t enough space. Therefore, Apple uses a clever solution. They embedded the antenna in the surface of a molded plastic cylindrical part. There, clever conductive plastic is used, with added metal. A laser engraves the exact shape of the antenna in the form of small channels with a rough surface. Then, this groove is subjected to electroplating, first with copper, then covered with gold to protect against corrosion. As a result, a durable conductive track is formed, which matches the 3D geometry of the molded part, which would be impossible to create using traditional machining methods. The plastic not only structurally supports the antenna. Other components are attached to it, such as the cable wrapping around the stem to connect the antenna to the Bluetooth chip, the pressure sensor in the stem.

Microphone. In AirPods, not electret microphones, but MEMS: a microelectronic” version of the condenser type. Well, actually, this is not only Apple – any modern TWS headphones, unless they are the cheapest ones. That is to say, modern microphones are made using the same technology as types – photolithography, layer by layer, only in this case it’s a mechanical device, with calculated cavities and flexible layers. Separately interesting is how they make the cavities – they make holes through which etching solution penetrates inside and dissolves the sacrificial layers of silicon dioxide.

Because of such microscopic size, there are several microphones. But why more than one microphone is needed? At the bottom of the AirPods, you will see a small mesh that allows air to enter the second microphone. When you talk, your voice reaches both microphones, but not at the same time. With a difference of only a few millimeters, the chip can detect a delay of six microseconds between when your voice reaches each microphone. This is enough to determine where the sound is coming from and focus on it. Since it precisely knows the distance the microphones are from one another, the chip can compare each signal and amplify your voice during calls.

The third microphone is for noise cancellation. It is located right in front of the speaker, inside your ear.

The microphones consume about 130 mA, which would quickly drain the battery if they were always active. That’s why they are only turned on when you make a call or use noise cancellation. But AirPods are always waiting for a Siri request. How is this possible without constantly active microphones? Here’s a clever solution. Inside the part that is in your ear, there is a small sensor—an accelerometer. It’s the same type of sensor used in phones to determine orientation. But here it serves a different purpose. Instead of measuring orientation, it senses vibration. When you talk, your voice moves through your jawbone. And this vibration is detected by the accelerometer. This low-power consumption signal is enough to wake up the system and activate the microphones when it senses you want to activate Siri. Imagine that, eh?

The sound in AirPods is tuned not “by ear,” but based on a scientific model of the “ideal sound” (Harman curve), which describes the combination of frequencies most people find most pleasing. For this, there is a complicated system of calculated vents and meshes — to control the air flow, which prevents the occurrence of unpleasant “humming” or sharp sounds inside the ear canal. The larger the cells — more air passes through, smaller — less. Such is the mesh, visible as black things on the white earphone—I thought it was for beauty. No, this is exactly that mesh. But at the same time, some kind of moisture protection must be made, and here the mesh is porous. It is claimed that there is some sort of nano-coating that repels water.

Bluetooth. Why it is so immune to interference. Turns out, it uses frequency-hopping spread spectrum technology (Frequency Hopping). Bluetooth devices quickly switch between different channels many times a second and adapt accordingly.

DIY Wireless Reaction Game: Building Interactive Button-Based Activities | July 28 2025, 22:26

Who knows their way around electronics? Any recommendations?

I want to make a thing some weekend. A big bulbous button. It lights up – you smash it. The app records the time from when it lights up to when it’s smashed. There might be several buttons and they could be scattered – on walls or the floor. WIRELESS. They might light up randomly – this is controlled by the app (phone or computer). Metrics like average reaction time are calculated on the fly for different understandings of the word ‘average’. For instance, you could place buttons on the ground a few meters apart and invent a moving game for the kids. Or attach them to a wall and smash them with a ball. Basically, it’s a technical question.

How would you do it – dumb buttons on an nRF24L01+ chip or smart buttons on an esp32 microcontroller?

In the first case, every such module listens to the radio: as soon as a command with its ID arrives from the central node, it turns on the light. After the button is pressed, it sends back a “pressed” message. The timer is on the side of the central node. Each button has an Arduino Pro Mini + nRF24L01+, but there will also be a central hub with either nRF24L01+ and Arduino Uno, Mega or ESP32, which collects the data and is connected to the computer (Bluetooth or WiFi).

In the second case, the buttons are connected via Bluetooth (BLE) or WiFi. The brains of the button is the ESP32, which needs to be programmed through a programmer.

Cost-wise, both approaches are roughly the same minus the cost of arcade buttons and 3D printing, somewhere around $10-15 per button.

Exploring the Intricacy of a 3200-Wire Copper Telephone Cable | July 12 2025, 15:11

Copper telephone trunk cable. Here are 3,200 (!) color-coded wires each 0.4 mm in diameter. Such cables are usually made up of twisted pairs (each pair consists of two wires), and 3,200 wires mean 1,600 pairs. The entire cable has a diameter of 9 cm and is produced in 250-meter segments. These segments need to be joined together, and then the ends connected to equipment. So, each of the 3,200 cores is carefully stripped and connected to the corresponding wire of the next segment. Probably a very entertaining activity.