Author: Jenny List

3311 Articles

A MIDI Sequencer To Be Proud Of

June 23, 2018 by 5 Comments

MIDI sequencers are surprisingly expensive, making them an excellent target for [RH Electronics] who has created a sixteen-step device. It supports up to eight playable parts per step, which can be either MIDI or drum triggers.

The case and front panel are built to a very high standard, and on a piece of stripboard within lies an ATmega644 which does all the MIDI work, an ATmega328 that runs the many LEDs, and an ATtiny85 that reads the front panel buttons. The whole is kept in sync by a timer on the 644 set to produce the required MIDI clock. There is an LCD display too, which carries the status and programming interface.

You can see the result in the video below the break, in which the sequencer is put through its paces alongside a tantalising glimpse of a matching synthesiser. Is this another project, or a commercial device on which Google fails us when we try to find it? Meanwhile this is certainly not the first MIDI sequencer we’ve brought you here at Hackaday, this Arduino one is another example of several also using Atmel parts.

Continue reading “A MIDI Sequencer To Be Proud Of” →

A Cleverly Concealed Magnetic Loop Antenna

June 23, 2018 by 39 Comments

We’re sure all radio amateurs must have encountered the problem faced by [Alexandre Grimberg PY1AHD] frequently enough that they nod their heads sagely. There you are, relaxing in the sun on the lounger next to the crystal-blue pool, and you fancy working a bit of DX. But the sheer horror of it all, a tower, rotator, and HF Yagi would ruin the aesthetic, so what can be done?

[Alexandre]’s solution is simple and elegant: conceal a circular magnetic loop antenna beneath the rim of a circular plastic poolside table. Construction is the usual copper pipe with a co-axial coupling loop and a large air-gapped variable capacitor, and tuning comes via a long plastic rod that emerges as a discreet knob on the opposite side of the table. It has a 10 MHz to 30 MHz bandwidth, and should provide a decent antenna for such a small space. We can’t help some concern about how easy to access that capacitor is, on these antennas there is induced a surprisingly large RF voltage across its vanes, and anyone unwary enough to sit at the table to enjoy a poolside drink might suffer a nasty RF burn to the knee. Perhaps we’d go for a remotely tuned model instead, for this reason.

[Alexandre] has many unusual loop projects under his belt, as well as producing commercial loops. Most interesting to us on his YouTube feed is this one with a capacitor formed from co-axial soft drink cans.

Thanks [Geekabit] for the tip.

There’s RC2014 Life In The TMS9918A Display Chip Yet

June 22, 2018 by 30 Comments

One of the outliers in the home computer wars of the early 1980s was the Texas Instruments TI99/4A. It may not have had the games library of its rivals and its TMS9900 processor may not have set the world on fire with its registers-in-RAM architecture, but its range of support chips included one whose derivatives would go on to delight subsequent generations. If you had an MSX or one of the 8 or 16-bit Sega consoles, the TMS9918A graphics chip provided the architecture that sat behind Sonic in his adventures.

A few decades later, there is still significant interest in this classic chip. [J.B. Langston] has an RC2014 retrocomputer, and wishing to play MSX demos upon it, has created a TMS9918A-based graphics card for the RC2014 bus. The success of the board hinges upon a circuit showing how to interface the 9918A to SRAM, and since it is mapped to the same ports as its MSX equivalent it should in theory be compatible with Z80 demos written for that platform. He’s already achieved some success with that aim, as can be demonstrated by the video we’ve placed below the break of the Bold MSX demo running on an RC2014.

The RC2014 has gained a significant following in the retrocomputer scene, and has appeared here many times. We reviewed an early model in 2016. Surprisingly though the TMS9918A has only appeared here once, as part of a homebrew 6809-based system.

Continue reading “There’s RC2014 Life In The TMS9918A Display Chip Yet” →

CNC Mod Pack Hopes To Make Something Useful From A Cheap Machine Tool

June 21, 2018 by 13 Comments

It is probable that many of us have noticed a variety of very cheap CNC mills in the pages of Chinese tech websites and been sorely tempted. On paper or as pixels on your screen they look great, but certainly with the more inexpensive models there soon emerges a gap between the promise and the reality.

[Brandon Piner] hopes to address this problem, with his CNC Mod Pack, a series of upgrades to a cheap mill designed to make it into a much more useful tool. In particular he’s created a revised 3D-printed tool holder and a set of end stop switches. The tool holder boasts swappable mounts on a dovetail fitting with versions for both a laser diode and a rotary tool, allowing much better tool positioning. Meanwhile the end stops are a necessary addition that protects both tool and machine from mishaps.

The same arguments play out in the world of small CNC mills as do in that of inexpensive 3D printers, namely that the economy of buying the super-cheap machine that is nominally the same as the expensive one starts to take a knock when you consider the level of work and expense needed to make your purchase usable. But with projects like this one the barrier to achieving a quality result from an unpromising start is lowered, and the enticing prospect is raised of a decent CNC machine for not a lot.

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Clock This! A 3D-Printed Escapement Mechanism

June 21, 2018 by 13 Comments

Traditional mechanical clockmaking is an art that despite being almost the archetype of precision engineering skill, appears rarely in our world of hardware hackers. That’s because making a clock mechanism is hard, and it is for good reason that professional clockmakers serve a long apprenticeship to learn their craft.

Though crafting one by hand is no easy task, a clock escapement is a surprisingly simple mechanism. Simple enough in fact that one can be 3D-printed, and that is just what [Josh Zhou] has done with a model posted on Thingiverse.

The model is simply the escapement mechanism, so to make a full clock there would have to be added a geartrain and clock face drive mechanism. But given a pair of 608 skateboard wheel bearings and a suitable weight and string to provide a power source, its pendulum will happily swing and provide that all-important tick. We’ve posted his short video below the break, so if Nixie clocks aren’t enough for you then perhaps you’d like to take it as inspiration to go mechanical.

A pendulum escapement of this type is only one of many varieties that have been produced over the long history of clockmaking. Our colleague [Manuel Rodriguez-Achach] took a look at some of them back in 2016.

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Hexabitz, Modular Electronics Made Easier

June 20, 2018 by 14 Comments

Over the years there have been a variety of modular electronic systems allowing the creation of complex circuits by the interconnection of modules containing individual functions. Hexabitz, a selection of interlocking polygonal small PCBs, is just such a system. What can it bring to the table that others haven’t done already?

The problem facing designers of modular electronics is this: all devices have different requirements and interfaces. To allow connection between modules that preserves all these connections requires an ever-increasing complexity in the inter-module connectors, or the application of a little intelligence to the problem. The Hexabitz designers have opted for the latter angle, equipping each module with an STM32 microcontroller that allows it to identify both itself and its function, and to establish a mesh network with other modules in the same connected project. This also gives the system the ability to farm off computing tasks to individual modules rather than relying solely upon a single microcontroller or single-board computer.

An extremely comprehensive array of modules can be had for the system, which lends it some interesting possibilities, however, it suffers from the inherent problem of modular electronic systems, that it is less easy to incorporate non-standard functions. If they can crack a prototyping module coupled with an easy way to tell its microcontroller to identify whatever function is upon it, they might have a winner.

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Definitely-Not-Neopixel Rings, From Scratch!

June 16, 2018 by 22 Comments

The WS2812 addressable LED is a marvellous component. Any colour light you want, all under the control of your favourite microcontroller, and daisy-chainable to your heart’s content. Unsurprisingly they have become extremely popular, and can be found in a significant number of the project s you might read about in these pages.

A host of products have appeared containing WS2812s, among which Adafruit’s Neopixel rings are one of the more memorable. But they aren’t quite as cheap as [Hyperlon] would like, so the ever-resourceful hacker has created an alternative for the constructor of more limited means. It takes the form of a circular PCB that apes the Adafruit original, and it claims to deliver a Bill of Materials cost that is 85% cheaper.

In reality the Instructables tutorial linked above is as much about how to create a PCB and surface-mount solder as it is specific to the pixel ring, and many readers will already be familiar with those procedures. But we won’t rest until everyone out there has tried their hands at spinning their own PCB project, and this certainly proves that such an endeavour is not out of reach. Whether or not you pay for the convenience of the original or follow this lead is your own choice.

The real thing has been in so many projects it’s difficult to pick just one to link to. This Christmas tree is rather nice.