Many a hacker spent their high school years picking up a few new skills in workshop classes. Whether it be woodworking, welding, or the patient, delicate skill of technical drawing, they’ve been a mainstay of secondary education for decades. However, composites are new enough that they aren’t a major feature of the curriculum. For those wishing to fill in a few gaps, [Easy Composites] have some great videos on carbon fibre techniques.

The video in question concerns the manufacture of a complex cross-section tube part, but these techniques can also apply to more complex hollow sections, like a bike frame, for example. Starting with a mold, the first step is to cut a rough template. This is then used to lay down the first layer of pre-preg carbon fibre material, and a more accurate template is made. The rest of the steps involve the production of a secure lap joint between subsequent layers, and how to properly use vacuum bag techniques on hollow parts.

It’s a useful primer on the basics of producing hollow carbon fibre parts with prepreg material. We’ve featured composites before, with this bulletproof armor a particularly good example. Video after the break.

source https://hackaday.com/2020/07/18/techniques-for-making-complex-carbon-fibre-tube-parts/

The low-cost LED has changed the way we approach lighting in all its forms, allowing complex addressable displays and all sorts of lighting goodness. But what did we do before we had cheap LED arrays? Use neon bulbs, perhaps? That’s exactly what [Manawyrm] has done with his chainable 8×8 neon matrix boards, taking 64 neon indicator bulbs and driving each from mains potential with an individual triac. A line of 74HC595s handle the data transfer, floating at mains voltage while their ESP32 driver is kept safe by a set of isolators.

A Twitter post shows it in action, but perhaps the most hackworthy praise should be reserved for his test rig. Unable to source a variable 230V mains supply for testing the array, he applied a 50 Hz sine wave to an audio power amplifier, and replaced the speaker with the low voltage side of a mains transformer. It’s the sort of hack we can’t help liking.

Neons have generally featured here as novelties rather than as significant displays in their own right. They’re interesting components that everyone should have a play with, not least because the possess negative resistance, and can be made to oscillate.

source https://hackaday.com/2020/07/18/forget-led-matrices-how-about-neon/

The Z80 is one of those old CPUs that is both obtainable and easy to work with — at least in some versions. [Doctor Volt] put together what may be the simplest possible setups to get a working Z80 system. He has the processor, of course. But everything else — clock, memory, and power — are from an Arduino Mega 2560. You could argue that’s two chips, but the board actually has several chips on it. On the other hand, you could probably pull off the same stunt with a bare ATMega 2560.

We’ve seen this done before, but usually with a few more support chips. If you are a purist, [Doctor Volt] also has some Z80 and CP/M experiments where the Arduino only acts as a disk drive for the computer and there are only two support chips. There are three videos for both projects that you can see below.

We were struck by how simple the first project was, though. Around 100 lines of source code is all it takes, and some of those are comments. The Arduino even provides the system memory (1K of it) and you initialize it by changing the memory.h file and reloading the Arduino.

The code does a bit of setup for interrupts and the clock and then just spins. The Arduino gets an interrupt on a CPU read and a different interrupt on a CPU write. All memory reads draw out of the simulated 1K RAM and memory writes go there, as well. The write code also can detect an I/O port write and sends that data to the Arduino serial port. It doesn’t appear to matter what I/O port you write to.

This reminded us of one of our favorite cheap Z80 projects. That board uses an ATMega32A in a similar way but also has external RAM. If you add a few EEPROMs to act as disk drives, it sits somewhere in the middle of the two computers from [Doctor Volt]. With so few parts, it is easy to get these 8-bit wonders in fairly small spaces.

source https://hackaday.com/2020/07/17/a-z80-board-with-very-few-parts/

You really should learn to read Morse code. But if you can’t — or even if you can, and just want a break — you can always get a computer to do it. For example, [jmharvey1] has a decoder that runs on a cheap Bluepill dev board.

The device uses a touchscreen and a few common components. The whole thing cost about $16. You can see it at work along with a description of the project in the video below.

The code uses the Arduino-style setup for the Blue pill — something we’ve talked about before. As for the decoding method, the software employs the Goertzel algorithm which is akin to a single frequency Fourier transform. That is, while a full transform gives you information about the frequency component of a signal across a wide range, the Goertzel algorithm probes the signal for one or a small number of distinct frequencies.

The decoder table looks confusing at first until you realize that each “decode” value consists of a 1 as a start bit followed by a 1 for a dash and a zero for a dot. All bits to the left of the start bit don’t count. So an “E” codes as 02 hex — a start bit followed by a single zero or dot. A “C” is 1A hex (1 + -.-.). Once you find the matching code, you apply the same index to another table to look up the actual letter or string of letters.

If you buy a Bluepill to make one of these, you might as well get two and build something to send code, too.

source https://hackaday.com/2020/07/17/bluepill-copies-code-so-you-dont-have-to/

Smart homes come with a lot of perks, not least among which is the ability to monitor the goings-on in your home, track them, and make trends. Each piece of monitoring equipment, such as sensors or cameras, is another set of wires that needs to be run and another “thing” that needs to be maintained on your system. There are sometimes clever ways of avoiding sensors, though, while still retaining the usefulness of having them.

In this build, [squix78] uses existing sensors for electricity metering that he already had in order to alert him when his oven is pre-heated. The sensor is a Shelly 3EM, and the way that it interfaces with his home automation is by realizing that his electric oven will stop delivering electricity to the heating elements once it has reached the desired temperature. He is able to monitor the sudden dramatic decrease in electricity demand at his house with the home controller, and use that decrease to alert him to the fact that his oven is ready without having to install something extra like a temperature sensor.

While this particular sensor may only be available in some parts of Europe, we presume the idea would hold out across many different sensors and even other devices. Even a small machine learning device should be able to tell what loads are coming on at what times, and then be programmed to perform functions based on that data.

source https://hackaday.com/2020/07/17/home-monitoring-without-all-the-sensors/

Many a hacker has dug an old flash drive out of the bottom of a backpack, and peeled apart the damaged plastic case to look inside. More often then not, you’d expect to see some SMD chips on a PCB along with a few passives, an LED and a USB port. [Gough] found something else entirely, and documented it for the interested public.

Inside the Comsol 8GB USB stick, [Gough] found an entire microSD card. One might be led to think this is a card reader and microSD masquerading as a normal flash drive, but the reality is far different. Instead, the drive contains a Flash memory controller which addresses the microSD card as raw NAND, through test points normally covered up on consumer-grade cards. The drive appears to be manufactured from factory second microSD cards that don’t pass the normal tests to be onsold to the public.

Armed with software obtained through spurious channels, [Gough] is able to dive deeper into the guts of the flash drive. The engineering tools allow the card to be optimised for capacity or speed, and different levels of error correction. It’s even possible to have the flash drive emulate a U3 CD ROM drive for OS installs and other purposes.

It’s a great dive into how USB drives work on a low level, and how the firmware and hardware work together. We’ve seen other flash drive hacks before too – like this simple recovery trick!

source https://hackaday.com/2020/07/17/usb-flash-drive-reveals-strange-sd-card-heart/

When it comes to cleaning your hands, [Arnov Sharma] is not messing around. He built an automatic soap dispenser using ultrasonic sensors, a stepper motor for activating the pump, and 3D printed components for housing a bottle of soap – a spectacular display of over-engineering. At least he won’t be needing to stand in line at the supermarket for motion detection soap dispensers anytime soon.

Initially, he had the idea to build the dispenser using a common servo motor-based method.  This would involve activating motors to push down on the plunger for the soap bottle to dispense soap. Instead, he for a different approach that ended up being fairly straightforward in theory, although the execution is pretty involved.

He started off by 3D printing the compartment where the soap bottle would sit and the structural support for the Z-axis rail that would be pushing down on the soap bottle. It’s similar to the type of linear actuator you might find in a 3D printer or PCB mill, where a motor controls a rotating screw that moves the carriage across a belt. (We presume the linear rail came first, and the ultrasonic soap dispenser second.)

In this build, there are two additional rods added to help support the lever pressing down on the soap dispenser.

 

The setup is controlled by an Arduino, which triggers the movement from the linear actuator if it receives a signal from an ultrasonic sensor. He’s added the model files and Arduino code for other makers curious about building a similar project. Check out his video for the soap dispenser in action – the stepper motor definitely makes for a much more powerful plunge than you might expect.

source https://hackaday.com/2020/07/17/this-soap-dispenser-will-crush-your-germs/