Vacuum Tubes: Shipping Through EBay Now Challenging?

January 20, 2018 by Jenny List 76 Comments

There is disquiet in the world of vacuum electronics, that something as simple as shipping a vacuum tube could now be very difficult to achieve. It’s a concern expressed among other places in a video by [Guitologist] that we’ve included below, and includes tales of vacuum tubes being impounded as either dangerous to ship, or not allowed to be shipped across international borders.

Upon investigation it appears that the common thread in all the stories lies with eBay’s Global Shipping Program, the centralised shipping service operated by the online auction giant. We reached out to eBay’s press office on the subject but have yet to receive a reply. It’s best to ask someone who ships a lot of tubes for comment when you have a tube shipping story, so we also had a conversation with TC Tubes. They’re a small company dealing in tubes, and as you might imagine they ship a lot of them (Their website is likely to detain you for a while if you are a tube-head). [Chelsea] from TC Tubes told us that they have encountered no regulatory barriers to tube shipping, and that their only bad experience has been yet again with eBay’s Global Shipping Program.

So it seems there is no cause for panic if you ship tubes, CE marking or RoHS rules haven’t come for your EL34s and your 6550s. Ebay have evidently got some kind of issue with tubes in their shipping operation, and perhaps you should ship by other means if you wish to avoid your tubes going astray. The consensus here among the Hackaday crew is that it could be as simple as uninformed employees not being aware of what tubes are because they aren’t as common as they used to be. After all, with over a hundred years of history behind them it’s not as though any potential issues with their shipping haven’t been comprehensively explored.

We’d still be interested to hear from eBay on the matter though, if they would care to comment.

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Know Your Video Waveform

January 18, 2018 by Jenny List 84 Comments

When you acquired your first oscilloscope, what were the first waveforms you had a look at with it? The calibration output, and maybe your signal generator. Then if you are like me, you probably went hunting round your bench to find a more interesting waveform or two. In my case that led me to a TV tuner and IF strip, and my first glimpse of a video signal.

An analogue video signal may be something that is a little less ubiquitous in these days of LCD screens and HDMI connectors, but it remains a fascinating subject and one whose intricacies are still worthwhile knowing. Perhaps your desktop computer no longer drives a composite monitor, but a video signal is still a handy way to add a display to many low-powered microcontroller boards. When you see Arduinos and ESP8266s producing colour composite video on hardware never intended for the purpose you may begin to understand why an in-depth knowledge of a video waveform can be useful to have.

The purpose of a video signal is to both convey the picture information in the form of luminiance and chrominance (light & dark, and colour), and all the information required to keep the display in complete synchronisation with the source. It must do this with accurate and consistent timing, and because it is a technology with roots in the early 20th century all the information it contains must be retrievable with the consumer electronic components of that time.

We’ll now take a look at the waveform and in particular its timing in detail, and try to convey some of its ways. You will be aware that there are different TV systems such as PAL and NTSC which each have their own tightly-defined timings, however for most of this article we will be treating all systems as more-or-less identical because they work in a sufficiently similar manner.

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Confessions Of A Reformed Frequency Standard Nut

January 17, 2018 by Jenny List 57 Comments

Do you remember your first instrument, the first device you used to measure something? Perhaps it was a ruler at primary school, and you were taught to see distance in terms of centimetres or inches. Before too long you learned that these units are only useful for the roughest of jobs, and graduated to millimetres, or sixteenths of an inch. Eventually as you grew older you would have been introduced to the Vernier caliper and the micrometer screw gauge, and suddenly fractions of a millimetre, or thousandths of an inch became your currency. There is a seduction to measurement, something that draws you in until it becomes an obsession.

Every field has its obsessives, and maybe there are bakers seeking the perfect cup of flour somewhere out there, but those in our community will probably focus on quantities like time and frequency. You will know them by their benches surrounded by frequency standards and atomic clocks, and their constant talk of parts per billion, and of calibration. I can speak with authority on this matter, for I used to be one of them in a small way; I am a reformed frequency standard nut. Continue reading “Confessions Of A Reformed Frequency Standard Nut” →

Four Pi Zeros, Four Cameras, One Really Neat 3D Scanner

January 17, 2018 by Jenny List 24 Comments

Sometimes when you walk into a hackerspace you will see somebody’s project on the table that stands so far above the norm of a run-of-the-mill open night on a damp winter’s evening, that you have to know more. If you are a Hackaday scribe you have to know more, and you ask the person behind it if they have something online about it to share with the readership.

[Jolar] was working on his 3D scanner project on just such an evening in Oxford Hackspace. It’s a neatly self-contained unit in the form of a triangular frame made of aluminium extrusions, into which are placed a stack of Raspberry Pi Zeros with attached cameras, and a very small projector which needed an extra lens from a pair of reading glasses to help it project so closely.

The cameras are arranged to have differing views of the object to be scanned, and the projector casts an array of randomly created dots onto it to aid triangulation from the images. A press of a button, and the four images are taken and, uploaded to a cloud drive in this case, and then picked up by his laptop for processing.

A Multi-view Stereo (MVS) algorithm does the processing work, and creates a 3D model. Doing the processing is VisualSFM, and the resulting files can then be viewed in MeshLab or imported into a CAD package. Seeing it in action the whole process is quick and seamless, and could easily be something you’d see on a commercial product. There is more to come from this project, so it is definitely one to watch.

Four Pi boards may seem a lot, but it is nothing to this scanner with 39 of them.

Remember Your Birthday For Fifty Years

January 16, 2018 by Jenny List 18 Comments

Our Coin Cell Challenge competition has turned up some amazing entries, things that we wouldn’t have thought possible from such meagre power sources. Take [Vishnu M Aiea]’s entry for instance, a device which he claims can light up as a birthday reminder every year for up to fifty years.

At its heart is a modified Arduino Nano clone that draws a measured 608 nA from a CR2450N. From the specification of the cell he has calculated the 50 year maximum figure, as well as a possible 29 years for a CR2032 and 64 years for a CR2477. He does however note that this does not take self-discharge into account, but you can probably afford a new battery in a decade or so.

The Arduino clone carefully selected for its “P” version low-power processor has had its serial bridge IC removed to achieve this power consumption, as well as a voltage regulator and some discrete components. Interestingly he notes that the ATMega168P is even more frugal than its 328 cousin, so he’s used the former chip. A selection of internal flags are set for minimal power consumption, and the internal oscillator is selected to use as low a clock speed as possible. There is an Intersil ISL1208 low power RTC chip mounted on a piece of stripboard to provide the timing, and of course an LED to provide the essential birthday alert.

When the LED lights for the big day there’s always the hope you’ll receive another coin cell, this time powering an edge-lit musical birthday card.

Is That Part A Counterfeit? Here Are A Few Pointers

January 15, 2018 by Jenny List 59 Comments

If you order an electronic component, how do you know what it is you are receiving? It has the right package and markings, but have you got the real thing from the original manufacturer or have you got an inferior counterfeit? We hear so much about counterfeit parts, and sometimes the level of effort put in by the fraudsters is so high that from either a visual or electrical standpoint they can be hard to spot.

[Robb Hammond] writes for Aeri, with an extremely interesting guide to some of the cues for spotting a counterfeit semiconductor part. In doing so he gives us something of an insight into the techniques used by the fraudsters.

The first feature of a package to be examined are the indents. Relabeled chips often have their old markings sanded off and a coating applied to simulate the surface of an unmolested chip, and this coating can either obliterate or partially fill any indentations. Using comparison photos we are shown discernable hidden indents, and partially filled indents.

We’re shown textures and paints, and how markings can sometimes be shown as counterfeit by washing with solvent. A Cypress-marked part is found to be a cheaper Altera one under the paint, and other parts are shown with misaligned markings and markings placed over indents. Wildly varying countries of origin are claimed while seemingly retaining the same batch codes, an impossibility confirmed by manufacturers.

If you order your parts from legitimate distributors then it’s likely that what you receive will be the genuine article. However with the popularity of online auction sites and online bazaars the possibility has become ever more likely of being left with a counterfeit. Knowing some of these tips might just make the difference between the success or failure of your work, so it’s an interesting read.

Have you had any dodgy parts on your bench? Tell us about them in the comments. Meanwhile, it’s a subject we’ve covered before.

Via Hacker News.

This Portable Pi May Not Be What You Expect

January 15, 2018 by Jenny List 25 Comments

In the years since the Raspberry Pi and other similar inexpensive Linux-capable single board computers came to the market, we have shown you a huge variety of projects using them at the heart of portable computers. These normally take the form of a laptop or tablet project, but today we have one that starts from a completely different perspective.

The “Kindleberry Pi Zero W” from [Ben Yarmis] does not attempt to create an enclosure or form factor for a portable computing solution. Instead it’s fair to say that it is more of a software hack than a hardware one, as he’s created something of an ad-hoc portable Raspberry Pi from other off-the-shelf pieces of consumer hardware.

The Zero W is a particularly useful computer for this application because of its tiny size, lowish power consumption, on-board Bluetooth, and wireless networking. He has taken a W and put it in the official Pi case, with a portable battery pack. No other connections, that’s his computer. As an input device he has a Bluetooth keyboard, and his display is a jailbroken Kindle Touch tied to the Pi using his Android phone as a WiFi router. We suspect with a little bit of configuration the Pi could easily serve that function on its own, but the phone also provides an Internet connection.

The result is a minimalist mobile computing platform which probably has a much longer battery life and higher reliability than portable Pi solutions using LCD displays, and certainly takes up less space than many others. Some might complain that there’s no hack in wirelessly connecting such devices, but we’d argue that spotting the possibility when so many others embark on complex builds has an elegance all of its own. It has the disadvantage for some users of providing only a terminal based interface to Raspbian, but of course we’re all seasoned shell veterans for whom that should present no problems, right?

Notable portable Pi solutions we’ve shown you before include this beautiful Psion-inspired project, and this one using the shell of an old laptop.