Arduino MKR Makes Nespresso Monitoring Easy

April 25, 2021 by Jenny List 23 Comments

Monitoring an appliance with a microcontroller usually follows a well-worn path of diving inside and finding somewhere in the electrical circuitry that can be connected through some kind of interface to a microcontroller. For his Nespresso pod coffee machine, [Steadman] eschewed tearing into the device, and instead chose to monitor the sound it makes. A commodity sound threshold sensor board is hooked up to an Arduino MKR Zero, and this set-up logs coffee consumption. It’s important to note how this generation of Arduino is no longer one of the simple boards of old, instead it sports an RTC and SD card alongside its SAMD21 Cortex-M0+ processor so it is perfect for just such a datalogging project. The coffee data can be saved into a CSV file viewable by a spreadsheet, for which code is provided.

We like this project for its non-invasive simplicity, and we can see that there could be plenty of other similar machines that could benefit from an analagous technique for non-invasive monitoring. While the pages of Hackaday are full of coffee machine projects we see surprisingly few pod coffeemakers, perhaps because our readers are a canny bunch who balk at paying a premium for their caffeine. If you do happen to have a Nespresso machine though, perhaps you’d like some help identifying the capsules.

Was Novell’s NE2000 Really That Bad?

April 24, 2021 by Jenny List 42 Comments

If you used almost any form of networked PC in the late 1980s or the 1990s, the chances are that you will at some point have encountered the Novell NE2000 network card. This 16-bit ISA card became a de facto standard for 16-bit network cards, such that very few “NE2000” cards were the real thing. A host of clones filled the market, some of which followed the spec of the original rather loosely. It’s something [Michal Necasek] examines as he takes the reader through the history of the NE2000 and why it gained something of a bad reputation. An interesting read for ’90s PC veterans who battled with dodgy Windows 3.1 network drivers.

The Novell line of network cards were not a primary product of the network server OS company but an attempt to spur the uptake of networked computers in an age when few machines were supplied from the factory with a network card installed. They were largely an implementation of the reference design for the National Semiconductor DP3890 Ethernet interface chipset, and for simplicity of interfacing and drivers they used an I/O mapped interface rather than DMA. The problem with the NE2000 wasn’t the card itself which would work with any NE2000 driver, but the host of “NE2000 compatible” cards that appeared over the decade as that magic phrase became a key selling point at the bottom end of the market. Sure they might contain a DP3890 or its clones, but even minor differences in behaviour would cause them not to work with all drivers, and thus they gained a bad name. The piece reveals the original card as one that might have been slow and outdated towards the end of its reign as a standard card, but maybe one not deserving of the ire directed at it.

If ancient networking kit is your thing, we’ve got some far more obscure stuff to show you.

A Modern Mac Using An Ancient Mac Display

April 24, 2021 by Jenny List 8 Comments

If you own an Apple product you probably live in a world with a few proprietary interfaces, but by and large your displays and desktop peripherals will use familiar ports such as USB and DisplayPort. For the Mac owner of yore though it was a different matter, as [Dandu] is here to tell us with the tale of a vintage Apple monochrome CRT monitor and a modern Mac.

There are no handy VGA ports to be found in this screen, instead it has a 15-pin D connector following a proprietary interface. With the right adapter it’s easy enough to produce VGA from the modern machine, but while it is in theory possible to map VGA pins to Apple pins there’s a snag with this particular model. Instead of using separate sync pins, it demands a composite sync of the type you might find in an analogue TV set that contains both horizontal and vertical sync pulses. The solution came through a simple transistor circuit, and then with the requisite settings on the modern Mac to deliver the 640×480 resolution it was possible to see a MacOS Catalina desktop on something more suited to a Mac II.

We’re more used to seeing CRT Macs in the form of the venerable SE/30, a machine that’s been on our radar for a long time.

Fail Of The Week: Mistaking Units For Values

April 24, 2021 by Jenny List 93 Comments

Usually when we post a Fail Of The Week, it’s a heroic tale of a project made with the best of intentions that somehow failed to hit its mark. The communicator that didn’t, or the 3D-printed linkage that pushed the boundaries of squirted plastic a little bit too far. But today we’re bringing you something from a source that should be above reproach, thanks to [Boldport] bringing us a Twitter conversation between [Stargirl] and [Ticktok] about a Texas Instruments datasheet.

The SN65220 is a suppressor chip for USB ports, designed to protect whatever the USB hardware is from voltage spikes. You probably have several of them without realising it, the tiny six-pin package nestling on the PCB next to the USB connector. Its data sheet reveals that it needs a resistor network between it and the USB device it protects, and it’s this that is the source of the fail.

There are two resistors, a 15kO and a 27O, 15k ohms, and 270 ohms, right? Looking more closely though, that 27O is not 270 with a zero, but 27O with a capital “O”, so in fact 27 ohms.

The symbol for resistance has for many decades been an uppercase Greek Omega, or Ω. It’s understood that sometimes a typeface doesn’t contain Greek letters, so there is a widely used convention of using an uppercase “R” to represent it, followed by a “K” for kilo-ohms, an “M” for mega-ohms, and so on. Thus a 270 ohm resistor will often be written as 270R, and 270 kilo-ohm one as 270K. In the case of a fractional value the convention is to put the fraction after the letter, so for example 2.7kilo-ohms becomes 2K7. For some reason the editor of the TI datasheet has taken it upon themselves to use an uppercase “O” to represent “Ohms”, leading to ambiguity over values below 1 kilo-ohm.

We can’t imagine an engineer would have made that choice so we’re looking towards their publishing department on this one, and meanwhile we wonder how many USB devices have gone to manufacture with a 270R resistor in their data path. After all, putting the wrong resistor in can affect any of us.

WSPR May Hold The Key To MH370 Final Position

April 24, 2021 by Jenny List 53 Comments

The disappearance of Malaysia Airlines flight MH370 after an unexplained course change sent it flying south over the Indian Ocean in March 2014 still holds the mystery of the wreck’s final location. There have been a variety of efforts to narrow down a possible search area over the years, and now we have news of a further angle from an unexpected source. It’s possible that the aircraft’s path could show up in radio scatter detectable as anomalously long-distance contacts using the amateur radio WSPR protocol.

WSPR is a low-power amateur radio mode designed to probe and record the radio propagation capabilities of the atmosphere. Transmit beacons and receiving stations run continuously, and all contacts however fleeting are recorded to an online database. This can be mined by researchers with an interest in the atmosphere, but in this case it might also provide clues to the missing airliner’s flightpath. By searching for anomalously long-distance WSPR contacts whose path crosses the expected position of MH370 it’s possible to spot moments when the aircraft formed a reflector for the radio waves. These contacts can then either confirm positions already estimated using other methods, or even provide further course points. It’s an impressive demonstration of the unexpected data that can lurk in a trove such as the WSPR logbook, and also that while messing about on the airwaves the marks we leave behind us can have more benefit than simply bragging rights over the DX we’ve worked.

If this WSPR business intrigues you, then have a read of the piece in our $50 Ham series about it.

Header: Laurent ERRERA from L’Union, France, CC BY-SA 2.0.

[via Southgate ARC]

“Paper” Bottles For Your Fizzy Drinks (And Bottle Rockets)

April 23, 2021 by Jenny List 144 Comments

A story that passed almost unnoticed was that the Coca-Cola company plan to run a limited trial of paper bottles. Wait, paper for a pressurized beverage? The current incarnation still uses a plastic liner and cap but future development will focus on a “bio-based barrier” and a bio composite or paper cap tethered to the vessel.

Given that plastic pollution is now a major global concern this is interesting news, as plastic drinks bottles make a significant contribution to that problem. But it raises several questions, first of all why are we seemingly unable to recycle the bottles in the first place, and given that we have received our milk and juice in paper-based containers for decades why has it taken the soda industry so long?

Plastic soft drink bottles are made from Polyethylene terephthalate or PET, the same polyester polymer as the one used in Dacron or Terylene fabrics. They’re blow-moulded, which is to say that an injection-moulded preform something like a plastic test tube with a screw top fitting is expanded from inside in a mould by compressed gas. As anyone who has experimented with bottle rockets will tell you, they are immensely strong, and as well as being cheap to make and transport they are also readily recyclable when separated from their caps.

Continue reading ““Paper” Bottles For Your Fizzy Drinks (And Bottle Rockets)” →

LibreVNA Is A Quality Open Hardware Vector Network Analyser

April 22, 2021 by Jenny List 39 Comments

There was a time when a Vector Network Analyser or VNA was the type of instrument that cost as much as a very fancy car or even a small house. The advent of commodity semiconductors that perform at high RF frequencies coupled with microcontrollers powerful enough to handle the data acquisition and processing might not yet have put those high-perfomance instruments within reach, but at our end of the market it’s opened the possibilities for some useful yet affordable devices. A fresh contender comes from [Jankae], whose LibreVNA tops out at 6 GHz and shows some significant attention to design detail that puts it above some of the budget offerings.

At its heart is the versatile Si5351 multi-way clock generator, accompanied by a pair of MAX2871 phase-locked-loop chips for the higher frequency local oscillators. A switched bank of low-pass filters take care of local oscillator harmonics, and in the receive chain there are ADL5081 mixers feeding a dual conversion IF running at 70 MHz and then 300 kHz. Finally the ADCs are Microchip’s MCP3313, and all is kept in sync by an FPGA and an STM32G431 microcontroller. The main data proccessing is offloaded to a host computer, with a software package and GUI able to be compiled on Windows, Linux, and OSX.

The PCB shows the attention to detail, not least in the power supply arrangements, with every major component receiving its own regulator to ensure no RF makes it down the power rails. It’s clear that a properly made LibreVNA won’t be as cheap as some of its rivals, but we think the corresponding performance hike would make the extra cost worthwhile.

If VNAs are new to you, we covered an introduction from [W2AEW] a while back.