Automatic Sunglasses, No Battery!

July 8, 2018 by Jenny List 26 Comments

There are some projects that are so simple they require very little description, and [Bobricius’s] automatic sunglasses definitely fit into that category. Their story starts with the fad for 3D displays a few years ago, a resurfacing of the movie business’s periodic flirtation with the third dimension in the hope of using the gimmick to bring in more moviegoers. There was a time when you could hardly encounter a new TV or graphics card without it coming with a pair of cheap plastic glasses with LCD panels instead of lenses that would alternately shutter the view for each eye to create the 3D illusion.

Of course, once everyone had seen the film with the blue aliens and tried a few other titles on their new toy, they grew tired of headaches, nausea, and half-brightness. The glasses gathered dust, and the fancy 3D telly never ventured beyond two dimensions again. Except for [Bobricius’s] glasses, that is, for he’s levered out the 3D driver electronics and replaced them with a tiny SOIC-8 solar cell. Light hits the cell, the LCD gets a charge and darkens, no light and they remain transparent. Similar to welding goggles — though they usually use a battery. It’s unclear whether they can get a little too dark on a really bright day and whether they are something akin to [Zaphod Beeblebrox]’s peril-sensitive sunglasses, but we really applaud the idea. They are so simple that this Hackaday write-up is probably longer than their write-up, but they remain a neatly executed idea and we like that.

You can, of course, use a battery, or achieve the same effect by more complex means. But if the [Beeblebrox] glasses are closer to your requirements, we’ve got that covered too.

Multi-Board Solder Stencils Explained

July 7, 2018 by Jenny List 13 Comments

There was a time when reflow soldering was an impossibly exotic process at our level, something that only the most superhuman of hackers could even dream of attempting. But a demystification of the process plus the ready availability of affordable PCB and stencil manufacture has rendered into the range of almost all constructors, and it is likely that many of you reading this will have done it yourself.

Screen-printing solder paste onto a single board presents a mild alignment challenge, but how about doing it with many boards at once? [Eric Gunnerson] had this problem with a small-volume board he’s selling, and not being in the happy position of having his PCBs supplied on a panel, had to create his own multi-board alignment jig and stencil. His write-up provides a comprehensive and fascinating introduction to the process whether you are an occasional dabbler or embarking on a production run as he is.

The problem facing any would-be stenciler is that the board has to be held in place reliably in the same alignment as the stencil. With a single board, it’s easy enough to do the usual thing of taping scraps of PCB board to constrain its edges and hold it in place as a rudimentary jig, then lower the stencil onto it. Perhaps you’ve used one of those commercial stencil jigs, in which a set of magnets hold the stencil in place, or maybe you use pins to line everything up.

[Eric] takes us through the process of creating a laser-cut alignment jig for twelve boards, and cutting a matching twelve-board stencil. This includes all the software side using Inkscape, the selection of materials to match PCB thickness, and some of the issues with cutting Mylar sheet for the stencil without shrinkage at the corners. He’s using pins for alignment, and he even finds a handy supply of those in the form of shelf support pins.

We’ve visited the world of reflowing many times before. If you’d like a primer, here’s our Tools of the Trade piece on it, and if you aren’t daunted by larger projects, here’s an account of a prototype run of a significantly complex board.

The PT2399 Delay/Echo Chip Data Sheet You Never Had

July 7, 2018 by Jenny List 13 Comments

If you are fortunate enough to have had the opportunity to play with an analogue-reel-to-reel tape recorder in a well-equipped studio, you probably looped the tape around to create an echo, or a delay in the audio. It was a desirable effect to have, but not a practical one for a guitar pedal or similar portable accessory. Silicon alternatives for creating delays have been in production since the 1960s, first the so-called bucket brigade delay lines that used a switched chain of on-chip capacitors, and more recently all-digital chips that process the delay by storing samples in RAM. One of the more popular of those is the Princeton Technology PT2399, but it comes with something of a snag for the experimenter in the form of a sparse data sheet. Thankfully the folks at [Electrosmash] have come to the rescue on that front with a thorough technical examination of the chip that should fill in any gaps in the official documentation.

After a brief examination of the range of chips of which the 2399 is a part, they dive right into the chip’s internals by rearranging the internal circuit diagram from the data sheet to the point at which it makes more sense. At which point the difference between the chip’s delay and echo functions becomes obvious, through the inclusion of a feedback path.

We then are taken through the pins, examining what lies behind the power supply and analog inputs and outputs. We are somewhere between a data sheet and an app note here, as some of this is information rarely present even in really good data sheets. Finally, we are taken through the chip’s performance, with real-world distortion and noise measurements. Armed with this page, the would-be PT2399 designer really can say they know what they are working with.

Surprisingly few PT2399s have appeared on these pages, however one did pop up in the Synthbike.

An Optical Mouse Sensor For Robotic Vision

July 6, 2018 by Jenny List 22 Comments

Readers with long memories will remember the days when mice and other similar pointing devices relied upon a hard rubber ball in contact with your desk or other surface, that transmitted any motion to a pair of toothed-wheel rotation sensors. Since the later half of the 1990s though, your rodent has been ever significantly more likely to rely upon an optical sensor taking the form of a small CCD camera connected to motion sensing electronics. These cameras are intriguing components with applications outside pointing devices, as is shown by [FoxIS] who has used one for robot vision.

The robot in question is a skid-steer 4-wheeled toy, to which he has added an ADNS3080 mouse sensor fitted with a lens, an H-bridge motor driver board, and a Wemos D1 Mini single board computer. The D1 serves a web page showing both the image from the ADNS3080 and an interface that allows the robot to be directed over a network connection. A pair of LiPo batteries complete the picture, with voltage monitoring via one of the Wemos analogue pins.

The ADNS3080 is an interesting component and we’d love see more of it. This laser distance sensor or perhaps this car movement tracker should give you some more info. We’ve heard rumors of them being useful for drones. Anyone?

Retrotechtacular: Constructing A Car Engine

July 4, 2018 by Jenny List 18 Comments

Oxford is a city world-famous for its university, and is a must-see stop on the itinerary of many a tourist to the United Kingdom. It features mediaeval architecture, unspoilt meadows, two idylic rivers, and a car plant. That’s the part the guide books don’t tell you, if you drive a BMW Mini there is every chance that it was built in a shiny new factory on the outskirts of the historic tourist destination.

A 1930s Morris Ten Series II. Humber79 [CC BY-SA 3.0].

The origins of the Mini factory lie over the road on a site that now houses a science park but was once the location of the Morris Motors plant, at one time Britain’s largest carmaker. In the 1930s they featured in a British Pathé documentary film which we’ve placed below the break, part of a series on industry in which the production of an internal combustion engine was examined in great detail. The music and narration is charmingly of its time, but the film itself is not only a fascinating look inside a factory of over eight decades ago, but also an insight into engine manufacture that remains relevant today even if the engine itself bears little resemblance to the lump in your motor today.

Morris produced a range of run-of-the-mill saloon cars in this period, and their typical power unit was one of the four-cylinder engines from the film. It’s a sidevalve design with a three-bearing crank, and it lacks innovations such as bore liners. The metallurgy and lubrication in these engines was not to the same standard as an engine of today, so a prewar Morris owner would not have expected to see the same longevity you’d expect from your daily.

Continue reading “Retrotechtacular: Constructing A Car Engine” →

A Pick-And-Place That Is A Work Of Art

July 4, 2018 by Jenny List 8 Comments

It’s a Holy Grail among hackerspaces, the possession of a pick-and-place machine. These robotic helpers for placing surface-mount components on PCBs are something of a gateway to electronic production, but they can carry a fearsome cost. Happily for the cash-strapped would-be electronic manufacturer, it is possible to build a pick-and-place for yourself. [Mcuoneclipse] has demonstrated this with a rather impressive build that works with the freely available OpenPnP software.

Superficially it shares much with what you might expect from a small CNC mill, in that it has a frame made from extruded aluminium that carries rails that trace an X and a Y axis supporting a tool head. But instead of a blade it has a box made from laser-cut ply that contains a camera and a vacuum pick-up tool that can collect a component from the tapes and deposit it in the correct point on the board. At the machine’s heart is a Smoothieboard, and the work is done by an assortment of solenoid valves and actuators. A huge amount of attention to detail has been paid to this build, with a holder for all the interchangeable nozzles for different component sizes, laser-cut mountings for all the motorised components, and automatic feeders for the SMD tapes all being carefully designed and built. Several iterations of the design are presented, in particular around the head itself which has passed through more than one form to remove as much vibration as possible. But don’t take it from us, have a look at the video we’ve pasted in below the break.

This isn’t the first pick-and-place machine we’ve brought you here at Hackaday. If you already have a 3D printer, would you consider this upgrade?

Continue reading “A Pick-And-Place That Is A Work Of Art” →

The Electric Vehicles Of EMF Camp: A Sinclair C5, (Almost) As It Should Have Been

July 4, 2018 by Jenny List 40 Comments

Most Hackaday readers will have heard of [Clive Sinclair], the British inventor and serial entrepreneur whose name appeared on some of the most fondly-recalled 8-bit home computers. If you aren’t either a Sinclair enthusiast or a Brit of a Certain Age though, you may not also be aware that he dabbled for a while in the world of electric vehicles. In early 1985 he launched the C5, a sleek three-wheeler designed to take advantage of new laws governing electrically assisted bicycles.

The C5 was a commercial failure because it placed the rider in a vulnerable position almost at road level, but in the decades since its launch it has become something of a cult item. [Rob] fell for the C5 when he had a ride in one belonging to a friend, and decided he had to have one of his own. The story of his upgrading it and the mishaps that befell it along the way are the subject of his most recent blog post, and it’s not a tale that’s over by any means.

The C5 was flawed not only in its riding position, the trademark Sinclair economy in manufacture manifested itself in a minimalist motor drive to one rear wheel only, and a front wheel braking system that saw bicycle calipers unleashed on a plastic wheel rim. The latter was sorted with an upgrade to a disc brake, but the former required a bit more work. A first-generation motor and gearbox had an unusual plywood housing, and the C5 even made it peripherally into our review of EMF Camp 2016, but it didn’t quite have the power to start the machine without pedaling. Something with more grunt was called for, and it came in the form of a better gearbox which once fitted allowed the machine to power its way to the Tindie Cambridge meetup back in April. Your scribe had a ride, but all was not well. After a hard manual pedal back across Cambridge to the Makespace it was revealed that the much-vaunted Lotus chassis had lived up to the Sinclair reputation for under-engineering, and bent. Repairs are under way for the upcoming EMF Camp 2018, where we hope we’ll even see it entering the Hacky Racers competition.