Author: John Elliot V

118 Articles

A photo of the robot and the controller

A Simple $25 Robot Based On The ESP32

October 25, 2025 by No comments

[Paul McCabe] wrote in to let us know about his $25 robot. This small wheeled robot is based on an ESP32 and made using cardboard and hot glue.

You drive the contraption using a Bluetooth game controller thanks to the Bluepad32 library, which boasts a long list of supported hardware. [Paul] provides a Bill of Materials (BoM), complete with current component pricing. We don’t know about you, but it struck us as funny that the microcontroller is less expensive than the battery! Ah, the times we live in. Also [Paul] assumes you already have an appropriate Bluetooth controller and doesn’t include that in the total cost.

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A frame from the two billion frames per second camera

Filming At The Speed Of Light, About One Foot Per Nanosecond

October 19, 2025 by 26 Comments

[Brian Haidet] published on his AlphaPhoenix channel a laser beam recorded at 2 billion frames per second. Well, sort of. The catch? It’s only a one pixel by one pixel video, but he repeats it over and over to build up the full rendering. It’s a fascinating experiment and a delightful result.

For this project [Brian] went back to the drawing board and rebuilt his entire apparatus from scratch. You see in December last year he had already made a video camera that ran at 1,000,000,000 fps. This time around, in order to hit 2,000,000,000 fps at significantly improved resolution, [Brian] updated the motors, the hardware, the oscilloscope, the signalling, the recording software, and the processing software. Basically, everything.

One of the coolest effects to come out of this new setup is how light appears to travel noticeably faster when coming towards the camera than when moving away from it. It’s an artifact of the setup: laser beams that reflect off of fog particles closer to the camera arrive sooner than ones that bounce back from further away. Or, put another way, it’s special relativity visualized in an experiment in [Brian]’s garage. Pretty cool.

If you found all this intriguing and would like to know more, there’s some bonus material that goes into much more depth.

A hand holding the circuit in its active state

2025 Component Abuse Challenge: A Self-Charging LED Flasher By Burkhard Kainka

October 18, 2025 by 8 Comments

[Tito] entered a Self-Charging LED Flasher into the Component Abuse Challenge. It’s a simple re-build of a design by the unstoppable [Burkhard Kainka], and while [Tito] doesn’t explain its workings in detail, it’s a clever experiment in minimalism, and a bit of a head-scratcher at the same time.

You press a button and an LED flashes.  But there is no battery, so how does it work? Maybe the schematic to the right here will help. Or does it confound? Look at it yourself before reading on and see if you can figure out how it works.

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A screen shot of Wireshark in action.

Hacking A Banned Chinese Security Camera

October 18, 2025 by 44 Comments

Over on YouTube [Matt Brown] hacks a Chinese security camera recently banned by the US government. If you didn’t hear about this you can find out more over here: Major US online retailers remove listings for millions of prohibited Chinese electronics.

After powering the camera with a power-over-Ethernet (PoE) adapter [Matt] sets about monitoring network activity with Wireshark. The first data comes from DNS for the host devaccess.easy4ipcloud.com, which whois reports is operated by Alibaba Cloud LLC in California. This is a Chinese owned company with servers in the United States.

[Matt] covers some basics of TLS and how it works. He then goes on to explain how a Man in the Middle (MITM) attack works at a high level. To setup a MITM attack against the camera [Matt] sets up some port redirections using iptables for ports 443, 15301, 8683, 9898, and 12337 which his Wireshark analysis indicates were being used. His MITM attack works, which means the device is not properly verifying its certificate signing chain.

[Matt] goes on to reverse engineer the custom UDP protocol used for transmitting video data. He uses a vibe-coded Python program along with ffmpeg for that and manages to reconstruct a few frames of video taken from the UDP packet capture.

We think it would be safe to say that [Matt] did indeed find a few security problems with the camera as-is, but we don’t think that’s the point of the ban. The real problem is that there is auto-update facilities for the device firmware which means that in future malicious software could be uploaded by the manufacturer in the form of a firmware update. So even if this device was secure against MITM attacks and didn’t send unencrypted video data over UDP you would still have the problem of the firmware update if there is no trust.

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A photo of the camera.

F/0.38 Camera Lens Made With Oil Immersion Microscope Objective

October 17, 2025 by 15 Comments

Over on YouTube [Applied Science] shows us how to make an f/0.38 camera lens using an oil immersion microscope objective.

The f-number of a lens indicates how well it will perform in low-light. To calculate the f-number you divide the focal length by the diameter of the aperture. A common f-number is f/1.4 which is generally considered “fast”.

We are told the fastest commercial lens ever used had f/0.7 and was used by Stanley Kubrick to shoot the film Barry Lyndon which was recorded only with candle light.

A microscope objective is a crucial lens that gathers and magnifies light to form an image. It plays a key role in determining the quality and clarity of the final magnified image produced by a microscope.

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The Texas Instruments branding with some schematic symbols in background.

More Than 100 Sub-Circuit Designs From Texas Instruments

October 15, 2025 by 18 Comments

We were recently tipped off to quite a resource — on the Texas Instruments website, there’s a page where you can view and download a compendium of analog sub-circuits.

Individual circuits can be downloaded in the form of PDF files. If you chose to register (which is free), you’ll also gain access to the pair of e-books listed at the bottom of the page: Analog Engineer’s Circuit Cookbook: Amplifiers and Analog Engineer’s Circuit Cookbook: Data Converters. The data converter circuits can be further subdivided into analog-to-digital converter (ADC) circuits and digital-to-analog converter (DAC) circuits.

There are more than 60 amplifier circuits including basic circuits, current sensing circuits, signal sources, current sources, filters, non-linear circuits (rectifiers/clamps/peak detectors), signal conditioning, comparators, sensor acquisition, audio, and integrated amplifier circuits using MSP430 microcontrollers.

You’ll also find 39 analog-to-digital converter (ADC) circuits including low-power, small size, and cost optimized circuits; level translation and input drive circuits; low-level sensor input circuits; input protection, filtering and isolation circuits; and commonly used auxiliary circuits. Finally, there are 15 digital-to-analog converter (DAC) circuits including audio outputs, auxiliary and biasing circuits, current sources, and voltage sources.

Thanks to [Lee Leduc] for letting us know over on the EEVblog Forum.

A photo of the old mechanical and new digital altimeters

Ben Eater Explains How Aircraft Systems Communicate With The ARINC 429 Protocol

October 14, 2025 by 7 Comments

Over on his YouTube channel the inimitable [Ben Eater] takes a look at an electronic altimeter which replaces an old mechanical altimeter in an airplane.

The old altimeter was entirely mechanical, except for a pair of wires which can power a backlight. Both the old and new altimeters have a dial on the front for calibrating the meter. The electronic altimeter has a connector on the back for integrating with the rest of the airplane. [Ben] notes that this particular electronic altimeter is only a backup in the airplane it is installed in, it’s there for a “second opinion” or in case of emergency.

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