diy

424 Articles

Wreck Your Mail Before You Check Your Mail

June 5, 2021 by 28 Comments

Every five years or so, I think it’s time to review my e-mail flow. (Oh no!) I run my own mail server, and you should too, but this means that I get to figure out managing and searching and archiving and indexing it all by myself. (Yippee!)

And I’ll be honest — sometimes I’m a bit of a luddite. I actually, literally have been using Mutt, or its derivative NeoMutt for maybe fifteen years, after a decade or so of mouse-intensive graphical mail readers. If e-mail is about typing words, and maybe attaching the occasional image, nothing beats a straight-up text interface. But what a lot of these simple mail clients lack is good search. So I decided to take that seriously.

Notmuch is essentially an e-mail database. It’s an e-mail searcher, tagger, and indexer, but it’s not much else. The nice thing is that it’s brutally fast. Searches and extraction of tagged subsets are faster than sending the same data back and forth to the Big G, and I have a ton more flexibility. It’s awesome. Of course good ol’ Mutt can work with Notmuch. Everything can. It’s Linux/UNIX. Continue reading “Wreck Your Mail Before You Check Your Mail” →

DIY USB Microphone Seems Overkill; Is Surprisingly In-Depth

June 2, 2021 by 4 Comments

Those of us who have been working from home through video calls for the past year can attest to the rising demand for conferencing gear such as webcams and microphones. Not wanting to spring for a boring off-the-shelf solution, serial hacker [Andy Brown] decided to design his own USB solution from scratch and show us the process from start to finish.

Deciding to go for a full digital design for the circuitry, the peripheral is based off of a MEMS microphone and an STM32 microcontroller doing the heavy lifting between it and a USB connection. [Andy] notes that MEMS microphones are very delicate and you have to design the PCB around the hole where the sound enters, which is why he went with a breakout board which has the component already soldered onto it.

As for the MCU, he reasons that since this is a off-one project which won’t be produced in large numbers, the 180 MHz ARM core shouldn’t be seen as overkill, since it also gives him more than plenty of headroom to do signal processing to make the sound clearer before sending it through to a computer by the USB audio device descriptor.

Once the components are chosen and the board designed, [Andy] goes into detail explaining the firmware he wrote for the STM32 to translate the PCM samples from the microphone’s I²S interface into a format better suited for the computer. He also describes how it then processes the audio, applying a graphic equalizer to reduce noise and then ST’s own Smart Volume Control filter, which works more like a compressor than a simple amplitude multiplication.

Finally, all files for the project, including board gerbers and the STM32 firmware are available at the bottom of his post, and to boot, a video demonstrating the project which you can check here after the break. [Andy]’s choice of microcontroller for this project is no surprise to us, given he’s already made his own development board for the STM32 G0 series. But if this digital microphone project is a bit too modern for you, why not try your hand at building a ribbon microphone instead?

Continue reading “DIY USB Microphone Seems Overkill; Is Surprisingly In-Depth” →

Modifying Lights For DIY Ambiance

May 23, 2021 by 13 Comments

The ESP32 and ESP8266 spread like wildfire a few years ago due to their small form factor, low price, and wireless capability. They didn’t just take over the DIY scene, though. Plenty of mass market products began to incorporate these tiny chips as well, which means that there are some interesting pre-made devices around that are ripe for modification. In this case, using an off-brand smart light bulb as a base for an semi-proprietary lighting setup.

The lighting in this build is a generic RGB light bulb with the ability to control its color over Wi-Fi. Since it has an ESP8266 chip in it, it can be made to work with Philips Hue lights with some minor modifications, allowing a much wider range of control than otherwise available. For this one, [Vadim] needed to pry open the bulb case to access the chip, then solder wires to it for reprogramming. It needed power during this step which meant plugging the resulting mess of wires back into a lamp socket, but after this step the new programming allows the bulb to be reprogrammed remotely.

After that step is complete, though, the generic bulb is ready for its inclusion into a Hue lighting system. In this case, [Vadim] is using diyHue, a Hue emulator that allows control of the bulbs without needing to use any cloud services, running on a BeagleBone. It’s a fairly comprehensive way of adding many different types and brands of bulbs to one system, and avoids any subscription models or the use of a cloud service, which is always something we can get behind.

Continue reading “Modifying Lights For DIY Ambiance” →

A Standing Desk On The Cheap

May 17, 2021 by 23 Comments

A programmer forced to work from home during the pandemic, [MrAkpla] was having back pains from sitting in front of the computer all day. He considered buying a standing desk, but all the various options didn’t fit with either his desk or his budget. Not to be deterred, he devised one of the simplest standing desk implementations that we’ve seen. It clearly works for him, because he’s been using it for one year now with great success. [MrAkpla] espouses three main benefits of his approach:

  • Cheap as heck
  • Five minute set up time
  • Uses your existing desk

These goals were accomplished. You can see in the video below that transition from sitting to standing is indeed as quick as he claims, is clearly inexpensive, and indeed it doesn’t require any modifications to his desk or furniture.

This design centers on a having an 80 cm long monitor arm, which is quite a range of adjustment. He’s using a monitor arm pole mount from UK manufacturer Duronic. Although they are having delivery problems these days because of Brexit issues, [MrAkpla] was able to get one delivered from existing inventory outside of the UK.

Admittedly, this is a crude design — in effect two trash bins and a board. But even if this doesn’t fit well with your office decor, its a great way to try out the concept of a standing desk without the up-front investment. By the way, [MrAkpla] is on the lookout for similar monitor mounting poles from non-UK manufacturers. If you have any recommendations, put them in the comments below. If you’re interested in a DIY standing desk that is on the opposite side of the complexity spectrum, check out this beauty that we covered back in the pre-pandemic era.

Continue reading “A Standing Desk On The Cheap” →

Diving Into The Details Of Keyboard Interfaces At The Gate-Level

April 7, 2021 by 5 Comments

Never doubt the value of a good teacher. Even if you know — or think you know — the material being presented, a good teacher can open your eyes to new ways of looking at things that will pay dividends you never expected.

That’s the feeling we got while watching [Ben Eater]’s latest video on building a keyboard interface (embedded below) for his breadboard 6502 computer. On the face of it, getting a keyboard to talk to a computer should be a simple job. [Ben] had previously looked at the serial protocol used by the old PS/2 keyboard and even built a wildly complex circuit out of discrete shift register chips to visualize the data being sent by the keyboard. The video below continues that work, this time concentrating on using the keyboard with his 6502 breadboard computer.

After some instructive preliminaries on interrupt programming, [Ben] dives into the logic-level details of teasing useful signals from the keyboard. His signal processing starts with some inverters and an RC network to turn multiple clock pulses into one logic level transition. Walking through this circuit step by step was the really interesting bit; even if you know that the answer is eventually going to be “Schmitt trigger,” getting to that point was really instructive.

Of course, what [Ben]’s videos mainly accomplish is making us want to follow along with him and build a breadboard computer of our own. From a low-rez VGA card to a reliable UART, following along with his discrete chip builds is always educational.

Continue reading “Diving Into The Details Of Keyboard Interfaces At The Gate-Level” →

Portable Telescope Rolls Anywhere

April 5, 2021 by 12 Comments

Since Galileo began observing celestial objects with a telescope, an almost uncountable number of improvements have been made to his designs and methods. Telescopes can now view anything from radio waves to gamma waves, come in a wide range of sizes and shapes, and some are also fairly accessible to hobbyists as well. In fact, several homemade telescopes are specifically designed for ease of use, portability, and minimum cost, like this portable ball telescope. (Google Translate from Italian)

The telescope was designed and built by [andrea console] and features a ball-shaped mount for the mirror which was built from a bowl. Ball designs like this are easier to orient than other telescopes since the ball allows for quick repositioning in any direction, but the main focus of this project was to investigate focal length with various accessories while also being as portable as possible. To that end, the mount for the eyepiece is on a lattice that assembles and disassembles quickly, and the ball and other equipment are easily packed. This makes transportation quick and easy and reduces weight compared to a more traditional, or even Dobsonian, telescope.

This build is impressive not just from having an extremely portable telescope, but also from [andrea console]’s documentation of the optics in his build. It includes some adjustable parts which can increase the magnification and has detailed notes on all of the finer points of its operation. The ball telescope is a popular build, and we’ve recently seen others made out of parts from IKEA as well.

Continue reading “Portable Telescope Rolls Anywhere” →

Reliable Frequency Reference From GPS

February 28, 2021 by 35 Comments

GPS technology is a marvel of the modern world. Not only can we reliably locate positions on the planet with remarkable accuracy and relatively inexpensive hardware, but plenty of non-location-based features of the technology are available for other uses as well. GPS can be used for things like time servers, since the satellites require precise timing in order to triangulate a position, and as a result they can also be used for things like this incredibly accurate frequency reference.

This project is what’s known as a GPSDO, or GPS-disciplined oscillator. Typically they use a normal oscillator, like a crystal, and improve its accuracy by pairing it with the timing signal from a GPS satellite. This one is a standalone model built by [Szabolcs Szigeti] who based the build around an STM32 board. The goal of the project was purely educational, as GPSDOs of various types are widely available, but [Szabolcs] was able to build exactly what he wanted into this one including a custom power supply, simple standalone UI, and no distribution amplifier.

The build goes into a good bit of detail on the design and operation of the device, and all of the PCB schematics and source code are available on the projects GitHub page if you want to build your own. There are plenty of other projects out there that make use of GPS-based time for its high accuracy, too, like this one which ties a GPS time standard directly to a Raspberry Pi.