A CRT Monitor Restoration

Nothing quite says vintage computer like a dedicated glass terminal. We enjoyed [Adam]’s restoration of an Acorn CRT monitor. The 14 inch display had a common problem: a defective power switch. Replacing a switch shouldn’t be a big deal, of course, but these old CRT monitors have exciting voltages inside and require special care.

One common issue, for example, is the fact that the old CRTs are really large capacitors and can hold a dangerous charge for some time. The easiest way to handle the potential problem is to make sure the device is unplugged, ground a screwdriver blade, and push the blade under the second anode cap. Most of the time, nothing happens. Once in a while, though, you’ll hear a loud pop and you just saved yourself a nasty shock.

Even though the actual repair was pretty mundane, the teardown was a great nostalgia trip and while we don’t want to give up our LCD, we do like the old glass. CRTs have a long history and came a long way before their last gasps. They even took a turn as mass storage devices.

Tesla Door Handle Improvements

Automotive engineer and former Tesla employee [SuperfastMatt] takes at look at the notorious Tesla door handle design and how it’s changed over the years (see the video below the break). The original handle design consisted of many moving parts, switches and wires which were prone to failure.  Strictly speaking, the door handle is located on the outside of the car’s interior. While it’s sheltered from direct exposure to the elements, it still experiences the extremes of temperature, humidity, and condensation. The handles were so prone to failure that a cottage industry sprang up to provide improved parts and replacements.

Tesla made various improvements over the years, culminating in the latest version which [Matt] reviews in this video. Nearly all the failure points have been eliminated, and the only moving parts, other than the handle itself, is a magnetic sensor to detect handle motion (previously this was sensed by microswitches). [Matt] indelicately opens up the control module, and discovers an NXP programmable angle sensor ( KMA215 ). This all-in-one sensor detects the angle of a magnetic field, and reports it over an automotive communications bus that’s become more and more common over the last ten years: Single Edge Nibble Transmission (SENT) aka SAE J2716. SENT is a low-cost, transmit-only protocol designed for sensors to send data to the ECU. Check out [Matt] decoding it on the oscilloscope and Raspberry Pi in the video — it looks pretty simple at first glance.

We agree with [Matt]’s conclusion that the door handle design has been significantly improved with this latest iteration, questions of whether one needs a retracting door handle aside. If you’d like to learn more about SENT, here is a tutorial written by IDT (now Renasas) applications engineer Tim White. This isn’t [Matt]’s first encounter with a Tesla door handle — back in 2012 we covered his project which used one to dispense beer. Thanks to [JohnU] for sending in this tip.

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Taking A Deep Dive Into SPI

With the prevalence of libraries, it has never been easier to communicate with hundreds of different sensors, displays, and submodules. But what is really happening when you type SPI.begin() into the Arduino IDE? In his most recent video, [Ben Eater] explores the Serial Peripheral Interface (SPI) and how it really works.

Most Hackaday readers probably know [Ben] from his breadboard-based computers, such as the 6502 build we featured in 2019. Since then he has been hard at work, adding new and interesting additions to his breadboard computer, as well as diving into different communication protocols to better understand and implement them. For this video, [Ben] set the goal of connecting the BME280, a common pressure, temperature, and humidity sensor with an SPI interface, to his breadboard 6502 computer. Along the way, [Ben] discusses how exactly SPI works, and why there is so much conflicting nomenclature and operations when looking at different SPI devices.

If breadboard computers aren’t your thing, there are tons of other uses for the BME280, such as helping to modernize a Casio F-91W.

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Farewell Sir Clive Sinclair; Inspired A Generation Of Engineers

It is with sadness that we note the passing of the British writer, engineer, home computer pioneer, and entrepreneur, Sir Clive Sinclair, who died this morning at the age of 81 after a long illness. He is perhaps best known among Hackaday readers for his ZX series of home computers from the 1980s, but over a lifetime in the technology industry there are few corners of consumer electronics that he did not touch in some way.

Sinclair’s first career in the 1950s was as a technical journalist and writer, before founding the electronics company Sinclair Radionics in the 1960s. His output in those early years was a mixture of miniature transistor radios and Hi-Fi components, setting the tone for decades of further tiny devices including an early LED digital watch at the beginning of the 1970s, miniature CRT TVs in the ’70s and ’80s, and another tiny in-ear FM radio which went on sale in the ’90s.

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A smartphone with a robot vacuum in the background

Hacking A Robot Vacuum To Write A Replacement App

While internet-connected devices can be very useful around the house, and it is pretty cool to be able to monitor your dishwasher from half a world away, it’s important to be mindful of privacy and security issues. For instance, the Cecotec Conga 1490 robot vacuum [Rastersoft] bought came with an Android app, which upon installation asked for near-total access to the user’s phone. Not content with such an invasion of privacy, let alone the potential security implications, [Rastersoft] set to work trying to reverse engineer the robot’s communications (translated) to find out what exactly it was doing when online. He did this by configuring a Raspberry Pi as an access point, letting the vacuum connect to it, and logging all the data flowing through.

As it turned out, the robot phoned home to its manufacturer, reporting its serial number and some configuration settings. The server then passed control to the mobile app, but not without routing all subsequent commands through the remote server. Not only is this creepy, it also means that if the manufacturer were to shut down the server, the app would stop working entirely. [Rastersoft] therefore got the idea to write custom software to control the robot. He began by reconfiguring the Pi’s network setup to fool the vacuum into thinking it was connecting to its manufacturer’s server, and then wrote some Python code to emulate the server’s response. He was now in control of all data flowing back and forth.

After a lot of experimentation and data analysis, [Rastersoft] managed to decipher the commands sent by the app, enabling him to write a complete replacement app seen in the video after the break that includes control of all the vacuum’s standard actions, but also a new feature to manually control the vacuum’s movement. All code is available on GitHub for those who would like to hack their Congas too.

We think this is a great example of software hacking to future-proof devices that you own, while also mitigating many of the dangers to your security and privacy posed by the default software. The fact that the commands you send from your phone to your vacuum go all the way around the world, potentially being stored and read by others, is rather ridiculous in the first place. After all, we’ve already seen how robot vacuums could spy on you.

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Powering Up With USB: Untangling The USB Power Delivery Standards

Powering external devices directly from a PC’s I/O ports has been a thing long before USB was even a twinkle in an engineer’s eye. Some of us may remember the all too common PS/2 pass-through leads that’d tap into the 275 mA that is available via these ports. When USB was first released, it initially provided a maximum of 500 mA which USB 3.0 increased to 900 mA.

For the longest time, this provided power was meant only to provide a way for peripherals like keyboards, mice and similar trivial devices to be powered rather than require each of these to come with its own power adapter. As the number of  computer-connected gadgets increased USB would become the primary way to not only power small devices directly, but to also charge battery-powered devices and ultimately deliver power more generally.

Which brings us to the USB Power Delivery (USB-PD) protocol. Confusingly, USB-PD encompasses a number of different standards, ranging from fixed voltage charging to Programmable Power Supply and Adjustable Voltage Supply. What are the exact differences between these modes, and how does one go about using them? Continue reading “Powering Up With USB: Untangling The USB Power Delivery Standards”

Continuous Resin Printer Shows The Speed

Redditor [No-Championship-8520] aka [Eric Potempa] has come up with an interesting DIY take on the Continuous Liquid Interface Production (CLIP) process currently owned and developed by Carbon Inc.

The usual resin 3D printer you may be familiar with is quite a simple machine. The machine has only one axis, which is the vertically moving build platform. A light exposes a photosensitive resin that cures on and is then pulled up off of a transparent window, before the next layer is exposed.

Typical resin printer setup

CLIP is a continuous resin printing process that speeds up printing by removing this peeling process. It utilises a bottom membrane that is permeable to oxygen. This tiny amount of oxygen right at the boundary prevents the solidified resin from sticking to the bottom, allowing the Z axis to be moved up continuously, speeding up printing significantly.

The method [Eric] is using is based around a continuously rotating bath to keep the resin moving, replenishing the resin in the active polymerisation zone. The bottom of the bath is made from a rigid PDMS surface, which is continuously wiped with a squeegee to replenish the oxygen layer. He notes the issues Carbon are still having with getting enough oxygen into the build layer, which he reckons is why they only show prints of smaller or latticed structures. His method should fix that issue. The build platform is moved up slowly, with the part appearing in one long, continuous movement. He reports the printing speed as 280 mm/hour which is quite rapid to say the least. More details are very scarce, and the embedded video a little unclear, but as one commentator said “I think we just saw resin printing evolve!” the next snarky comment changed the “evolve” to “revolve” which made us giggle.

Now, we all know that 3D printing is not at all new, and only the expiration of patents and the timely work by [Adrian Bowyer] and the reprap team kickstarted the current explosion of FDM printers. Resin printers will likely be hampered by the same issues until something completely new kickstarts the next evolution. Maybe this is that evolution? We really hope that [Eric] decides to write up his project with some details, and we will be sitting tight waiting to pore over all the gory details. Fingers crossed!