Author: Jenny List

3537 Articles

EU Duty Changes, A Whole VAT Of Trouble For Hackers?

March 10, 2020 by 105 Comments

It could be said that there are a number of factors behind  the explosion of creativity in our community of hardware hackers over the last couple of decades, but one in particular that is beyond doubt is the ease with which it has been possible to import small orders from China. See something on AliExpress and it can be yours for a few quid, somewhere in a warehouse on the other side of the world it’s put into a grey shipping bag, and three weeks later it’s on your doorstep. This bounty has in no small part been aided by a favourable postage and taxation environment in which both low postage costs and a lack of customs duties on packages under a certain value conspire to render getting the product in front of you a fraction of the cost of buying the thing in the first place. Continue reading “EU Duty Changes, A Whole VAT Of Trouble For Hackers?” →

The Best Voltage And Current Reference This Side Of A Test Lab

March 10, 2020 by 16 Comments

When you measure a voltage, how do you know that your measurement is correct? Because your multimeter says so, of course! But how can you trust your multimeter to give the right reading? Calibration of instruments is something we often trust blindly without really thinking about, but it’s not always an impossible task only for a high-end test lab. [Petteri Aimonen] had enough need for a calibrated current source to have designed his own, and he’s shared the resulting project for all to see.

The cost of a reference source goes up with the degree of accuracy required, and can stretch into the many millions of dollars if you are seeking the standards of a national metrology institute, but fortunately [Petteri]’s requirements were considerably more modest. 0.02% accuracy would suffice. An Analog Devices precision voltage reference driving a low-offset op-amp with a driver transistor supplies current to a 0.01% precision resistor, resulting in a reference current source fit for his needs. The reference is available in a range of voltages, his chosen 2.048 volts gave a 2.048 mA current sink with a 100 ohm resistor.

In a way it is a miracle of technology that the cheapest digital multimeter on the market can still have a surprisingly good level of calibration thanks to its on-chip bandgap voltage reference, but it never hurts to have a means to check your instruments. Some of us still rather like analogue multimeters, but beware — calibration at the cheaper end of that market can sometimes be lacking.

John Deere And Nebraska’s Right To Repair, The Aftermath Of A Failed Piece Of Legislation

March 9, 2020 by 99 Comments

For the past few years now we’ve covered a long-running battle between American farmers and the manufacturers of their farm machinery, over their right to repair, with particular focus on the agricultural giant John Deere. The manufacturer of the familiar green and yellow machinery that lies in the heart and soul of American farming has attracted criticism for using restrictive DRM and closed-source embedded software to lock down the repair of its products into the hands of its dealer network.

This has been a hot-button issue in our community as it has with the farmers for years, but it’s failed to receive much traction in the wider world. It’s very encouraging then to see some mainstream coverage from Bloomberg Businessweek on the subject, in which they follow the latest in the saga of the Nebraska farmers’ quest for a right to repair bill. Particularly handy for readers wishing to digest it while doing something else, they’ve also recorded it as an easy-to-listen podcast.

We last visited the Nebraska farmers a couple of years ago when they were working towards the bill reaching their legislature. The Bloomberg piece brings the saga up to date, with the Nebraska Farm Bureau failing to advance it, and the consequent anger from the farmers themselves. It’s interesting in its laying bare the arguments of the manufacturer, also for its looking at the hidden aspect of the value of the data collected by these connected machines.

It’s likely that the wider hardware hacker community and the farming community have different outlooks on many fronts, but in our shared readiness to dive in and fix things and now in our concern over right to repair we have a common purpose. Watching these stories at a distance, from the agricultural heartland of the European country where this is being written, it’s striking how much the farmers featured are the quintessential salt-of-the-earth Americans representing what much of America still likes to believe that it is at heart. If a company such as John Deere has lost those guys, something really must have gone wrong in the world of green and yellow machinery.

Header image: Nheyob / CC BY-SA 4.0

Velocity Based Training, With A Camera

March 8, 2020 by 3 Comments

In the world of weight training, the buzzword of the moment is VBT, or Velocity Based Training. This involves sensors being used to measure the speed and position of a weight as it moves through each repetition, and thus provide instant feedback for the athlete and glean information from which they can work upon their training routine. Typically the sensors involved may be accelerometers, but [Kris] has taken a different tack using a webcam and machine vision to do the same job.

The barbell has a green disc attached to its end, and the software tracks it and measures the velocity. It issues a warning when the velocity of a repetition drops below a preset level, telling the athlete to stop their set before pushing themselves too far. Under the hood is a Python script and OpenCV, and the write-up in his GitHub repository takes us through its camera calibration to remove the effects of distortion, and set-up. All calibration of distances within the image is made through the known size of the green disc, allowing the software to accurately chart the distance through which it travels.

We’ve not seen a machine vision approach to weight training before, but we have seen one using accelerometers. Maybe this project will re-ignite interest in this field.

That Retro Video Look, Without The Tapes

March 7, 2020 by 11 Comments

We’re lucky to live in an age of rapid technological advancement, lucky in more ways than one because as well as receiving a constant supply of new things, we have the benefit of the older tech that once we lusted over, at knock-down prices. [Luke Baker] spent his youth as a skateboarder, and the cameras of desire in that community were the high-end MiniDV models. They may not have high definition but their output has a Millennial aesthetic that captures the period, so he’s brought one into the 2020s by adding a digital SD card recorder designed for a multirotor to it.

On the face of it this is a pretty straightforward job of coupling an off-the-shelf recorder to a battery and the camera’s analogue output terminals. But the resulting spaghetti on what is supposed to be a portable device is hardly attractive, so he’s created an all-in-one 3D-printed enclosure that is attached to the camera’s handle with a set of cable ties. It’s shaped to fit the recorder and has a sliding lid over the battery compartment, and he’s added a handy on-off switch. Whether or not he takes it to the skate park in a bid to roll back the decades, as you can see int he video below the break it’s a well-executed piece of work that should serve to remind that there’s still life in some of this easily-available old tech if you’re prepared for a bit of lateral thinking.

This isn’t the first vintage video hack we’ve seen, back in 2016 we were treated to the grainy period feel of a vintage 8mm camera through the eye of a Raspberry Pi.

Continue reading “That Retro Video Look, Without The Tapes” →

An 8085 Retrocomputer From The Heart

March 7, 2020 by 22 Comments

The world of 8-bit retrocomputing splits easily into tribes classified by their choice of processor. There are 6809 enthusiasts, 6502 diehards, and Z80 lovers, each sharing a bond to their particular platform that often threads back through time to whatever was the first microcomputer they worked with. Here it’s the Z80 as found in the Sinclair ZX81, but for you it might be the 6502 from an Apple ][. For [Craig Andrews] it’s the 8085, and after many years away from the processor he’s finally been able to return to it and recreate his first ever design using it. The SBC-85 is not wire-wrapped as the original was, instead he’s well on the way to creating an entire ecosystem based around an edge-connector backplane.

The CPU board is an entire computer in its own right as can be seen in the video below the break, and pairs the 8085 with 8k of RAM, a couple of 2732 4k EPROMs, and an 8155 interface chip. This last component is especially versatile, providing an address latch, timer, I/O ports, and even an extra 256 bytes of RAM. Finally there is some glue logic and a MAX232 level shifter for a serial port, with no UART needed since the 8085 has one built-in. The minimal computer capable with this board can thus be slimmed down significantly, something that competing processors of the mid 1970s often struggled with.

Craig’s web site is shaping up to be a fascinating resource for 8085 enthusiasts, and so far the system sports that backplane and a bus monitor card. We don’t see much of the 8085 here at Hackaday, perhaps because it wasn’t the driver for any of the popular 8-bit home computers. But it’s an architecture that many readers will find familiar due to its 8080 heritage, and could certainly be found in many control applications before the widespread adoption of dedicated microcontrollers. It would be interesting to see where Craig takes this next, with more cards, and perhaps making a rival to the RC2014 over in Z80 country.

Continue reading “An 8085 Retrocomputer From The Heart” →

Vanquish Your Foes With Lego Playing Card Machine Gun

March 7, 2020 by 14 Comments

There was something exceptionally satisfying about those playground games of cops and robbers when we were young, but they were missing something in that a pretend gun made with your fingers lacks a certain Je ne sais quoi. Our youthful blood-lust demanded something a bit more real, and though the likes of NERF and other toys could supply it their lost projectiles came at a price not all parents could sustain. We’d have given anything for [Brick Experiment Channel]’s rapid-firing Lego playing card gun! (Video, embedded below.)

The principle is simple enough, one of the larger Lego road wheels is spun up to a respectable speed through a gear train from a pair of motors, it’s positioned over a channel through which playing cards are fed, and it picks each one up and accelerates it to a claimed 20 miles per hour. The card is fired off into the distance, ready to take down your Lego figure or plastic drinking cup enemies with maximum prejudice.

It’s clear some significant thought has gone into the firing platform design, with the cards sliding along smooth rails and the wheel sitting in a gap between the rails so that the natural springiness of the card can engage with it. The cards also emerge with a spin, due to the wheel being offset. The mechanism is completed with a third motor which acts as a feeder pushing individual cards from the deck into the main firing platform. This achieves an astonishing six cards per second, as can be seen in the video below the break.

We can see that this is a huge amount of fun, and we hope should any youngsters get their hands on it that there are not lurid tales of kids with playing card injuries. It’s not the first novelty projectile gun we’ve brought you, there have been numerous rubber band guns but our favourite is the automatic paper plane folder and launcher.

Continue reading “Vanquish Your Foes With Lego Playing Card Machine Gun” →