High-Speed Spectrometer Built With Cheap Linear CCD

November 21, 2020 by Tom Nardi 37 Comments

If you’ve ever dreamed of building a proper spectrometer, it looks like the ESPROS epc901 CCD sensor is absolutely worth your attention. It’s fast, sensitive, easy to interface with, and at just $24 USD, it won’t break the bank. There’s only one problem: implementing it in your project means either working with the bare 2×16 0.5 mm pitch BGA device, or shelling out nearly $1,400 USD for the development kit.

Thankfully, [Adrian Studer] has come up with a compromise. While you’ll still need to reflow the BGA to get it mounted, his open hardware breakout and adapter boards for the ESPROS epc901 make the sensor far easier to work with.

It’s not just a hardware solution either, he also provides firmware code for the STM32L4 based Nucleo development board and some Python scripts that make it easy to pull data from the sensor. The firmware even includes a simple command line interface to control the hardware that you can access over serial.

With the sensor successfully wrangled, [Adrian] partnered with [Frank Milburn] to build an affordable spectrometer around it. The design makes use of a 3D printed chamber, a simple commercial diffraction grating, and an array of entrance slits ranging from 0.5 to 0.0254 millimeters in width that were laser-cut into a sheet of stainless steel.

In the videos after the break, you can see the finished spectrometer being used to determine the wavelength of LEDs, as well as a demonstration of how the high-speed camera module is able to study the spectral variations of a CFL bulb over time. [Adrian] tells us that he and [Frank] are open to suggestions as to what they should point their new spectrometer at next, so let them know in the comments if you’ve got any interesting ideas.

We’ve seen an incredible number of spectrometer builds over the years, and some of the more recent ones are really pushing the envelope in terms of what the DIY scientist is capable of doing in the home lab. While they’re still fairly niche, these instruments are slowly but surely finding their way into the hands of more curious hackers.

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New Part Day: Bouffalo Labs BL602 RISC-V Wi-Fi/Bluetooth SoC

November 20, 2020 by Jenny List 20 Comments

We should all by now be used to microcontrollers with wireless hardware on board, with Espressif or Nordic Labs dominating the hacker scene. There have been several other contenders in this arena over the years that haven’t really caught the attention of our community, usually because of the opacity of their available information.

A new contender should be worth a second look though. The BL602 from Bouffalo Labs is a Wi-Fi- and Bluetooth LE-capable microcontroller with a 32-bit RISC-V derived core. If that doesn’t interest you much, perhaps news that the PINE64 folks are spearheading an effort to reverse engineer it for a fully open-source blob-free wireless implementation might sharpen your attention.

So where can you get your hands on one? Hold your horses, this chip is at an early stage in its gestation. We can see that there are some exciting possibilities in store, but we’re still figuring out the hardware interfaces and other software required to make it work. A community is hard at work reverse engineering it, which leads us back to the PINE64 story we mentioned earlier.

You can find BL602 modules from AliExpress vendors, but the PINE64 folks will offer you a free one if you join their blob reverse engineering effort. Take note though, this offer is for those prepared to show commitment to the project, so don’t spam them in the hope of free stuff if you won’t be helping deliver the goods.

We might see the BL602 gaining an open-source toolchain and internal blobs over the coming months thanks to the efforts of those working on it. Just as the ESP8266 did back in 2014, it’s starting as a black box with a relative scarcity of information. But if this hacking effort pays off, we’ll have a cheap RISC-V Wi-Fi and Bluetooth module with entirely open-source software from the silicon upwards. What a time to be alive!

Thanks [Renze] for the tip.

E-Paper Weather Display Is A Great Base To Build From

November 3, 2020 by Tom Nardi 26 Comments

As e-paper modules have become more affordable, we’ve started to see them pop up more and more in hacker projects. It used to be that you had to force a second-hand Kindle to do your bidding, but now you can buy just the screen itself complete with a header to plug right into your Raspberry Pi. It will still cost you as much as a used Kindle…but at least it comes with some documentation and there are Python libraries to talk to it.

But where to start? If you need some inspiration, and perhaps a little source code, this very slick weather display put together by [James Howard] is a great as baseline. Not that it really needs any additional refinement, as we think it already looks gorgeous. But rather than starting from scratch for your own project, it would be much easier to graft some additional functionality onto his code.

A lot of that has to do with how concise and well commented his code is. We’ve seen enough of these projects to know the kind of spaghetti that’s often running on the backend, but there’s none of that here. [James] assembles the display using the powerful Pillow graphics library, which lets you draw primitives and drop in text and icons with just a couple lines of code.

Once all the data is plugged in, the entire screen is saved as an image file which is then opened up on the e-paper display. Even if you aren’t a Python expert, you should be able to understand what’s happening and how to bend it to your will.

We’ve always had high hopes for electronic paper, and it seems the technology might finally be hitting critical mass. While it’s still a bit expensive, we’ve started seeing it pop up in unexpected places to great effect. Hopefully projects like this one will inspire others to take the B&W plunge.

Bringing High Temperature 3D Printing To The Masses

October 28, 2020 by Tom Nardi 77 Comments

Despite the impressive variety of thermoplastics that can be printed on consumer-level desktop 3D printers, the most commonly used filament is polylactic acid (PLA). That’s because it’s not only the cheapest material available, but also the easiest to work with. PLA can be extruded at temperatures as low as 180 °C, and it’s possible to get good results even without a heated bed. The downside is that objects printed in PLA tend to be somewhat brittle and have a low heat tolerance. It’s a fine plastic for prototyping and light duty projects, but it won’t take long for many users to outgrow its capabilities.

The next step up is usually polyethylene terephthalate glycol (PETG). This material isn’t much more difficult to work with than PLA, but is more durable, can handle higher temperatures, and in general is better suited for mechanical parts. If you need greater durability or higher heat tolerance than PETG offers, you could move on to something like acrylonitrile butadiene styrene (ABS), polycarbonate (PC), or nylon. But this is where things start to get tricky. Not only are the extrusion temperatures of these materials greater than 250 °C, but an enclosed print chamber is generally recommended for best results. That puts them on the upper end of what the hobbyist community is generally capable of working with.

Industrial 3D printers like the Apium P220 start at $30,000.

But high-end industrial 3D printers can use even stronger plastics such as polyetherimide (PEI) or members of the polyaryletherketone family (PAEK, PEEK, PEKK). Parts made from these materials are especially desirable for aerospace applications, as they can replace metal components while being substantially lighter.

These plastics must be extruded at temperatures approaching 400 °C, and a sealed build chamber kept at >100 °C for the duration of the print is an absolute necessity. The purchase price for a commercial printer with these capabilities is in the tens of thousands even on the low end, with some models priced well into the six figure range.

Of course there was a time, not quite so long ago, where the same could have been said of 3D printers in general. Machines that were once the sole domain of exceptionally well funded R&D labs now sit on the workbenches of hackers and makers all over the world. While it’s hard to say if we’ll see the same race to the bottom for high temperature 3D printers, the first steps towards democratizing the technology are already being made.

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What’s In A USB-C Connector?

October 27, 2020 by Jenny List 30 Comments

Anyone who’s ever put together a bill-of-materials for an electronic device will be familiar with the process of scouring supplier catalogs and data sheets for the best choice of components. The trick is to score the best combination of price and performance for the final product, and for those unused to the process, there are always seemingly identical products with an astonishingly wide variety of prices. It’s a topic [Timon] explores in a Twitter thread, examining a 20-cent in quantity of 100 USB-C socket alongside one that costs only 5 cents, and his teardown provides a fascinating insight into their manufacture.

The parts look so nearly identical that while it’s possible to differentiate between them visually, it’s near impossible to work out which was the cheaper. Some tiny features such as a crack in a metal fold or a bit less plating on the contacts emerge, but even then it’s no guide to the quality as they don’t appear on the same part. It’s only when the metal shell is removed to expose the underlying plastic moulding that more clues emerge, as one moulding is more complex than the other. The more complex moulding provides a better and more reliable fit at the expense of a much more costly moulding process, so at last we can not only identify the more expensive part but also see where the extra cash has gone. It’s a subtle thing, but one that could make a huge difference to the performance of the final assembly and which makes for a fascinating expose for electronic design engineers.

If connectors are your thing, there’s a wealth of fascinating information in their history.

Plastic Strips Protect Ball Screws On This Homebrew CNC Router

October 26, 2020 by Dan Maloney 17 Comments

It’s a fact of life for CNC router owners — swarf. Whether it’s the fine dust from a sheet of MDF or nice fat chips from a piece of aluminum, the debris your tool creates gets everywhere. You can try to control it at its source, but swarf always finds a way to escape and cause problems.

Unwilling to deal with the accumulation of chips in the expensive ball screws of his homemade CNC router, [Nikodem Bartnik] took matters into his own hands and created these DIY telescopic ball screw covers. Yes, commercial ball screw covers are available, but they are targeted at professional machines, and so are not only too large for a homebrew machine like his but also priced for pro budgets. So [Nikodem] recreated their basic design: strips of thin material wound into a tight spring that forms a tube that can extend and retract. The first prototypes were from paper, which worked but proved to have too much friction. Version 2 was made from sheets of polyester film, slippery enough to get the job done and as a bonus, transparent. They look pretty sharp, and as you can see in the video below, seem to perform well.

It’s nice to see a build progress to the point where details like this can be addressed. We’ve been following [Nikodem]’s CNC build for years now, and it really has come a long way.

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Improved Flexible Build Plate For SLA Is Ready To Rock

October 26, 2020 by Donald Papp 25 Comments

The Elegoo Mars is an affordable SLA (resin-based) 3D printer, and there are probably few that have seen more mods and experimentation than [Jan Mrázek]’s machine. The final design of his DIY flexible build plate is a refinement of his original proof of concept, which proved a flexible build platform can be every bit as useful on an SLA printer as it is for FDM; instead of chiseling parts off a rigid build platform, simply pop the flexible steel sheet off the magnetic base and flex it slightly for a much easier part removal process. His original design worked, but had a few rough edges that have since been ironed out.

We love how [Jan] walks through all of the design elements and explains what worked and what didn’t. For example, originally he used a galvanized steel sheet which was easy enough to work with, but ended up not being a viable choice because once it’s bent, it stays bent. Spring steel is a much better material for a flexible build platform, but is harder for a hobbyist to cut.

Fortunately, it’s a simple job for any metal fabrication shop and [Jan] got a variety of thicknesses cut very cheaply. It turns out that the sweet spot is 0.3 mm (although 0.2 mm is a better choice for particularly fragile parts.) [Jan] also suggests cutting the sheet a few millimeters larger than the build platform; it’s much easier to peel the sheet off the magnetic base when one can get a fingertip under an edge, after all.

The magnetic base that the steel sheet sticks to is very simple: [Jan] converted a stock build platform by mounting an array of 20 x 20 x 1 mm magnets with 3M adhesive mounting tape. He was worried that resin might seep in between the magnets and cause a problem, perhaps even interfering with the adhesive; but so far it seems to be working very well. Resin is viscous enough that it never penetrates far into the gaps, and no effect on the adhesive has been observed so far.

Watch how easily parts are removed in the short video embedded below, in which [Jan] demonstrates his latest platform design.

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