Author: Jenny List

3411 Articles

Build Your Own CRT TV

February 9, 2022 by 40 Comments

There was a time following the Second World War when TV sets for the nascent broadcast medium were still very expensive, but there was an ample supply of war-surplus electronic parts including ex-radar CRTs. Thus it wasn’t uncommon at all for electronics enthusiasts of the day to build their own TV set, and magazines would publish designs to enable them. With a burgeoning consumer electronics industry the price of a new TV quickly dropped to the point of affordability so nobody would consider building one themselves today. Perhaps that should be amended to almost nobody, because [Retro Tech or Die] has assembled a small black-and-white CRT TV from a kit he found on AliExpress.

We have to admit to having seen the same kit and despite a sincere love for analogue telly, to have balked at the price. It’s an exceptionally cheap set of the type that was available from discount stores for a laughably low price around the final few years of mainstream analogue TV broadcasting, and having a couple in the stable we can confirm that the value here lies in building the thing rather than owning it.

The unboxing and building proceeds as you might expect, with the addition of very poor documentation and extremely low-quality parts. Satisfyingly it works on first power-up, though some adjustment and the reversing of a deflection yoke connection is required for a stable picture. The scanned area doesn’t fill the screen and he doesn’t find the solution in the video, we hope that by his next video someone will have suggested moving the deflection yoke forwards.

Perhaps merely assembling a kit might not seem the most exciting subject for a Hackaday story, but this one is a little different here in 2022. CRT TV sets are now a long-gone anachronism, so for a younger generation there is very little chance to see them up close and thus watching one built has some value. If you want to spend the cash and build your own he’s dropped the link in the YouTube description, otherwise watch the progress in the video below the break.

Fancy learning a bit more about analogue TV? Have a dive into the video waveform. Or for a bit more CRT goodness, learn about converging a delta-gun colour set from the days when a TV weighed almost as much as you did.

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It’s Always Floppy Time!

February 9, 2022 by 9 Comments

On [Jan Derogee]’s desk is something that wouldn’t look out of place for many of us, a pile of computer magazines with a case of 3.5″ floppy disks on top of it. The causal observer would see nothing more than the detritus of a retrocomputer enthusiast’s existence, but stick around. In fact it’s a clock, and one of the most unusual ones we’ve seen in a long time.

How can a box of floppies tell us the time? Selected disks have custom labels that look as though they might be authentic game collections, but in reality are fakes that carry numbers alongside the game art. An ingenious system of cams hidden in the hollowed out pile of magazines raises the correct floppies to tell the time, hours on the left row and minutes to the closest five minutes on the right. The floppies are modified by the removal of some plastic and the disk itself, because early versions had a habit of shredding disks. A final touch comes in the form of a Nokia phone on the desk next to the clock which plays a tune in lieu of chimes on the hour. You can see the clock in action in the video below the break.

Continue reading “It’s Always Floppy Time!” →

A Bugatti Without The Inconvenience Of Wealth

February 8, 2022 by 52 Comments

There are many of us who might have toyed with the idea of building a car, indeed perhaps more than a few readers might even have taken to the road in a machine of their own creation. Perhaps it was a design of your own, or maybe a kit car. We think that very few of you will have gone as far as [Vũ Văn Nam] and his friends in Vietnam. In their latest video they compress a year’s work into 47 minutes as they craft a beautifully built replica of a Bugatti supercar. If you haven’t got a few million dollars but you’ve got the time, this is the video for you.

The skill involved in making a scratch-built car is impressive enough, but where there guys take it to the next level is in their clay modeling to create the moulds for the fibreglass bodywork. Taking their local clay and a steel frame, they carefully hand-sculpt the car with the skill of an Italian master stylist, before clothing it in fibreglass and removing the clay. The resulting fibreglass shell can be used to make the finished bodywork, which they do with an exceptional attention to detail. It might be a steel-tube home-made spaceframe with a wheezy 4-cylinder Toyota engine behind the driver instead of a 1000 HP powerhouse, but it surely looks the part!

Looking at the construction we’re guessing it wouldn’t pass an Individual Vehicle Approval test for roadworthiness where this is being written, but at the same time it wouldn’t be impossible to incorporate the extra work as this is a proper road-going car. The video is below the break, and though the few pieces of dialogue in it are in Vietnamese you probably won’t need to turn on the auto-translate to follow it.

This isn’t their first fake supercar, there’s already a Ferrari in this particular stable. Meanwhile if you’re of a mind to make a car, consider the world’s most hackable vehicle.

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Gaming Twitter’s Trending Algorithm To Make A Point

February 5, 2022 by 13 Comments

If you have ever taken to Twitter to gauge the zeitgeist, you’ll have noticed that among the trending hashtags related to major events of the day there are sometimes outliers of minority interest associated with single-issue causes. When a cause with a distasteful pedigree was cited one as proof of widespread public support in a debate in the UK’s House of Lords there were concerns raised that a flaw in the ranking algorithm might be responsible, and it was left to [Mallory Moore] to prove the hypothesis by getting a #ThisIsAnExploit hashtag trending without a groundswell of popular support.

Some previous detective work had established that equal ranking might be awarded equally not simply for Tweeting a hashtag but also for retweeting it. The exploit takes advantage of this by means of a relatively small cadre of people all Tweeting the tag a number of times, then retweeting all other instances of it. The resulting rank gain is then in the order of the square of the number of accounts interacting with the tag, and thus hugely inflated over the number of real participants. To test this she created the #ThisIsAnExploit tag and asked her followers to do just that: Tweet it and retweet all others containing it. In a short time the exploit succeeded, beating a very high-profile tag associated with the travails of the British Prime Minister in the process, and with most of the effort due to only 50 accounts.

Our world is now significantly influenced by social media because for many it appears more trustworthy than the old-style mass media with a print origin. Work like this is important because a reminder that transferring the message from newspaper proprietors to tech barons does not confer credibility is sorely needed. Meanwhile now the weakness is in the wild we wonder how Hackaday readers might have fun with it. Does anyone want to see a #RaiseTheJollyWrencher hashtag top the pile?

How To Spot A Fake Op-Amp

February 5, 2022 by 21 Comments

We’re all aware that there are plenty of fake components to be found if you’re prepared to look in the right places, and that perhaps too-good-to-be-true chip offers on auction sites might turn out to have markings which rub off to reveal something completely different underneath. [IMSAI Guy] saw a batch of OP-07 laser-trimmed op-amps at a bargain price, so picked them up for an investigation. You can take a look at the video below the break.

A perfect op-amp has a zero volt output when both of its inputs are at the same voltage, but in practice no real device approaches this level of perfection. It’s referred to as the offset voltage, and for instrumentation work where a low offset voltage is important there are parts such as the OP-07 which have each been adjusted using a laser to trim their components for the lowest offset. This process is expensive, so naturally so are genuine OP-07s.

Identifying real versus fake op-amps in this case is as simple as hooking the chip up as a unity gain non-inverting amplifier and measuring the voltage on the output (we can’t help a tinge of envy at that Keithley 2015 THD multimeter!), from which measurement the fakes should be clearly visible. First up are some 741s with their > 1 mV offsets (though an outlier 741 had a 40μV offset) to show what a cheap op-amp could be expected to do, then we see the OP-07s. Immediately with an offset of > 1.2 mV  we can tell that they’re fake, which as he admits for the price is hardly a surprise. Meanwhile we’ll keep an eye out for Korean-made 741s like the outlier low-offset device.

If you’re interested by op-amp internals may we suggest a look at the first IC op-amp, meanwhile this isn’t the first fake chip we’ve seen.

Continue reading “How To Spot A Fake Op-Amp” →

The Fifteen Dollar Linux Computer

February 4, 2022 by 66 Comments

Over the years we’ve seen many small computer boards of various abilities, among them many powerful enough to be almost-useful Linux general purpose computers. We’ve also seen more than a few computers that claimed the impossible, usually an amazing spec for a tiny price tag. Here for once is a small computer that’s neither of those two; a minimum viable Linux handheld terminal whose $15 USD price tag is openly discussed as a target price for a large production run rather than touted as its retail price.

It’s the work of legendary former Hackaday writer [Brian Benchoff], and instead of being merely a PCB it’s a fully usable computer with case, keyboard and display. It’s based upon an Allwinner F1C100s SoC, it’s powered by AAA cells, and it sports a split rubber keyboard that likely builds on his previous experience with the VT-69 portable RS-232 terminal. On the back is a USB port and an SD reader, and in the centre of the front panel lies a 320 x 240 pixel display. It’s important to note that this is not intended to run a GUI, while it’s DOOM-capable it remains very much a command-line Linux tool. Perhaps most interestingly it’s claimed that all the parts are available in quantity here in the chip shortage, so maybe there’s even a chance we might see it as more than a project. We can hope.

Thanks [Sathish Guru V] for the tip.

Copyright, What You Need To Know

February 4, 2022 by 54 Comments

Last week brought the story of a group of crypto enthusiasts who paid well over the going rate for a rare sci-fi book, then proposed encoding scans of all its pages in a blockchain before making and selling NFTs of them. To guarantee their rarity the book was then to be burned. Aside from the questionable imagery surrounding book burning in general, one of the sources of mirth in the story was their mistaken idea that in buying a copy of a rare book they had also acquired its copyright rather than simply paying too much for a book.

It’s an excuse for a good laugh, but it’s also an opportunity to talk about copyright as it affects our community. I’m not a lawyer and I’m not here to give legal advice. Instead this is based on the working knowledge gathered over decades working in the content publishing industries. Continue reading “Copyright, What You Need To Know” →