Have LED Bulbs Reached Their Final (and Cheapest) Form?

February 16, 2020 by 129 Comments

[electronupdate] has done a lot of LED light bulb teardowns over the years, witnessing a drive towards ever-cheaper and ever-simpler implementations, and suspects that LED light bulb design has finally reached its ultimate goal. This teardown of a recent dollar store example shows that cost-cutting has managed to shave even more off what was already looking like a market saturated with bottom-dollar design.

The electrical components inside this glowing model of cost-cutting consists of one PCB (previously-seen dollar store LED bulb examples had two), eleven LEDs, one bridge rectifier, two resistors, and a controller IC. A wirewound resistor apparently also serves as a fuse, just in case.

Inside the unmarked controller IC. The design is as cheap as it is clever in its cost-cutting.

That’s not all. [electronupdate] goes beyond a simple teardown and has decapped the controller IC to see what lurks inside, and the result is shown here. This controller is responsible for driving the LEDs from the ~100 Volts DC that the bridge rectifier and large electrolytic cap present to it, and it’s both cheap and clever in its own way.

The top half is a big transistor for chopping the voltage and the bottom half is the simple control logic; operation is fast enough that no flicker is perceived in the LEDs, and no output smoothing cap is needed. The result, of course, is fewer components and lower cost.

Some of you may recall that back in the early days of LED lighting, bulbs that could last 100,000 hours were a hot promise. That didn’t happen for a variety of reasons and the march towards being an everyday consumable where cost was paramount continued. [electronupdate] feels they have probably reached that ultimate goal, at least until something else changes. They work, they’re cheap, and just about everything else has been successfully pried up and tossed out the door.

Make A Set Of Headphones From Scratch

February 16, 2020 by 7 Comments

There are a variety of ways to enjoy your audio, of which headphones are one. Making a set of headphones is a straightforward enough project, but [madaeon] has taken the art to a new level by building the headphone drivers from scratch rather than using an off-the-shelf pair.

The result is a set of moving coil drivers with a construction technique involving using the semi-opaque thin window from an envelope as a diaphragm and as a former for the coil. Cyanoacrylate adhesive holds everything in place. The diaphragm is suspended across the mouth of a cardboard tube with the coil positioned above a magnet, resulting in the minimum moving mass necessary for as good a sound reproduction as possible. Judge for yourself, there’s a video that we’ve placed below the break.

The drivers are placed in a set of 3D-printed on-ear holders, and while they probably won’t match an expensive set of commercial headphones, we’d hazard a guess that they won’t have too bad quality. At the very least, it’s an interesting design to base further experimentation on.

Surprisingly few home made speaker or headphone drivers have made it onto these pages, probably because of the ubiquity of the ready-made article. An exception is this flexible PCB speaker, and of course we’ve also talked about home made electrostatic speakers. Continue reading “Make A Set Of Headphones From Scratch” →

Making Your Own Maple Syrup Just Got A Little Easier

February 16, 2020 by 23 Comments

[ctstarkdesigns] had fond memories of collecting maple syrup as a child. At the same time, he also remembered the work involved: from lugging buckets around on an unstable snow mobile to accidentally burning the mixture and making all the effort for naught. So he set out to make things a little easier this time around by building his own evaporator.

The build starts as many do, with a surplus 44-gallon drum. With an off-the-shelf kit, and some cutting and welding, it’s readily repurposed into a stove capable of burning wood in a roaring fire. From there, it’s a simple matter of making a few further incisions to install warming trays, used to hold the takings from the maple trees. There, the mixture can be boiled down into the tasty, delicious substance that goes so perfectly on pancakes.

The build has the dual benefits of both easing the boiling process and keeping the user warm while doing so. Already, the rig has proven itself as an adept heater, and we’re sure it will only prove more popular once it’s producing sweet maple syrup en mass. If that’s not enough, consider building an entirely automated system in your back yard!

GitHub Goes GUI-less

February 15, 2020 by 11 Comments

Git is a handy tool that many of us are using for more than just software development. Having a cloud-based upstream repository is also surprisingly useful, but until now using GitHub — the most common upstream server — meant firing up a web browser, at least for certain tasks. Now GitHub is releasing a beta version of command-line tools made to manipulate your GitHub repos.

The tools are early release so they mostly focus on issues and pull requests. Of course, git itself will do the normal things like clone and checkout — you’ve always been able to do that on the command line. The example given in the announcement blog post lists all issues with a help wanted label:

gh issue list --label "help wanted"

We noticed that asking to view the issue, while done on the command line, will still open a browser. The tools are still a little early, so this is an excellent time to let the developers know what you’d like or otherwise influence the project.

We were a little surprised it wouldn’t just consume git, so that you’d use the same commands for everything and it would just pass pre-formed commands to git. Of course, that would be pretty easy to write as a shell script wrapper if you were interested in such a thing.

You’d be forgiven for only thinking of git as a way to manage source code revisions, but it’s actually capable of all sorts of interesting tricks.

Wall Panels With 3760 Antennas Can Increase Wireless Range

February 15, 2020 by 34 Comments

Most of us know that to get the best possible WiFi signal, you want there to be as few walls as possible between you and the Access Point. But that might soon change, as researchers at MIT have found a way to make surfaces increase signal strength. Called RFocus, the technique uses a wall panel covered in simple antennas to dynamically focus or reflect RF energy towards a intended receiver.

The normal methods to increase wireless range usually involve increasing the transmitter output or adding larger, more efficient, or directional antennas to the receivers and transmitters. But these techniques are limited when you need to the reduce power consumption and size of the devices. The MIT teams approached the problem from a completely different angle, by optimizing the environment.

The wall panel in question consist of 94 PCBs, each containing 40 passive antenna elements in the form of copper rectangles. Each element is a quarter wavelength long (125 mm for 2.4 Ghz), and on its own it doesn’t have any real effect on the signals, allowing it to pass through the panel. Between the ends of elements are small RF switches, that can close to combine two antenna elements into single half wavelength antenna, creating a reflector. When this is applied across the panel in different patterns it can effectively beamform the signal to focus it at different points in space.

The RF switches are connected to shift registers, which are all controlled via a single SPI bus with an Arduino. Each RF switch is activated in a pseudo-random sequence, changing the configuration of the panel 10,000 times in 100 ms. The signal strength at the receiver is reported to the panel controller for each configuration, allowing the controller to select the best configuration for any single transmitter. In a scenario where multiple low-power sensor nodes are deployed, this can allow the receiver to “focus” on each node in turn. The full paper is a very interesting read, downloadable as a PDF.

RF is generally considered the black magic of electronics, but it can all become a bit clearer with a basic knowledge of antenna theory and modulation schemes.

Thanks to [Qes] for the tip!

Sequence Your Beats With The Magic Of Magnets

February 15, 2020 by 10 Comments

Typically, when we think of a music sequencer, we envisage LEDs and boards covered in buttons. Of course, there are naturally other ways to build such a device. MesoTune takes a different tack entirely, relying on magnets and rotating mechanisms to get the job done.

MesoTune acts as a MIDI controller, and is designed to be hooked up to a computer or other MIDI synthesizer device. The heart of MesoTune is a set of eight magnet wheels, rotating together on a common shaft. The rotational speed of the shaft, dictated by the requested tempo in beats per minute, is controlled by an Arduino. Each magnet wheel has 16 slots into which the user can place a spherical magnet. Every time a magnet on the wheel passes a hall sensor, it sends a MIDI message to the attached computer which is then responsible for using this to synthesize the relevant sound.

There are other useful features, too. Each of the eight magnet wheels, or channels, gets its own fader, which can be used to control volume or other parameters. There’s also a handy tempo display, and a 16-button touchpad for triggering other events. These additions make it more practical to use in a compositional context, where it’s nice to have extra controls to make changes on the fly.

Made out of 3D printed parts and readily available off the shelf components, it’s a fun alternative sequencer design that we’re sure many makers could whip up in just a weekend. We’d love to see other remixes of the design – if you’ve got one, hit us up at the tipline. We’ve seen other great sequencer builds before, too. Video after the break.

AAA Powered LoRa Mailbox Sensor Goes The Distance

February 15, 2020 by 29 Comments

As more of the world’s communication moves into the electronic realm, a casualty has come in the physical mail. Where once each new day might have brought with it a bulging mailbox, today it’s not uncommon for days to pass with not even so much as a bill or a coupon book. For [Eivholt] this presents a problem: he doesn’t want to miss a parcel but most visits to the mailbox are futile. His solution is a LoRa-connected mailbox monitor that sips power from a pair of AAA batteries to the extent that so far it’s run for over two years on a single set.

At its heart is a single board, a Talk2 Whisper Node. This packs a low-power version of the ATmega328 microcontroller alongside a LoRa radio and an efficient power regulator allowing it to draw only 8.70 uA in standby mode, waking up only for extremely short periods to check for mail and report via LoRa to The Things Network. The sensor is simply a microswitch, selected after finding a reed switch problematic to install. Finally an SDR was used to debug the operation of the radio.

The write-up also provides an introduction to extreme low power projects, including some tips on measuring such tiny currents. Even if you have no interest in a mailbox, any tricks that can help maximize power efficiency are always worth taking a look at. Check out the video after the break to see this radio-equipped mailbox in action.

Continue reading “AAA Powered LoRa Mailbox Sensor Goes The Distance” →