As anyone who is a veteran of many RF projects will tell you, long component leads can be your undoing. Extra stray capacitances, inductances, and couplings can change the properties of your design to the point at which it becomes unfit for purpose, and something of a black art has evolved in the skill of reducing these effects.
RF Biscuit is [Georg Ottinger]’s attempt to simplify some of the challenges facing the RF hacker. It’s a small PCB with a set of footprints that can be used to make a wide range of surface-mount filters, attenuators, dummy loads, and other RF networks with a minimum of stray effects. Provision has been made for a screening can, and the board uses edge-launched SMA connectors. So far he’s demonstrated it with a bandpass filter and a dummy load, but he suggests it should also be suitable for amplifiers using RF gain blocks.
It’s a tough challenge, to produce a universal board for multiple projects with very demanding layout requirements such as those you’d find in the RF field. We’re anxious to see whether the results back up the promise, and whether the idea catches on.
This appears to be the first RF network prototyping board we’ve featured here at Hackaday. We’ve featured crystal filters before, and dummy loads though, but nothing that brings them all together. What would you build on your RF Biscuit?
If there’s one console that holds a special place in the hearts of console gamers of a certain age, it’s the Atari 2600. A 6502 based system with a cartridge slot and a couple of joysticks, it plugged into your home TV and if you had one for Christmas in the late ’70s you were suddenly the coolest kid in the neighbourhood.
The last new 2600s were sold in the early 1990s, but all was not lost for 2600 fans. In the last decade the format was revived as the Atari Flashback, an all-in-one console containing a selection of games and no cartridge slot. The Flashback had a flaw though, it stayed true to the original in that it needed a TV set. Rather a pity in a world of hand-held consoles.
There isn’t a lot of room in a 2600 cartridge, so as her worklog shows, she had to cut up the PCB and be very careful with her wiring to ensure it all fits. She’s using the Flashback 2 as her source console, and she tells us it has 42 games to choose from.
If the worklog pictures weren’t enough she’s posted a video of the device in action, and it shows a very neat and playable hand-held console. We would have done anything to get our hands on one of those had it been available in 1980!
When most of us think of forge work, the image that comes to our mind is likely to be a rather traditional one, of the village blacksmith’s shop, roaring coke-fired hearths, and an anvil ringing to the beat of hand-wielded hammers. Iron and steel, worked through the sweat of the human brow.
Precision metalwork probably doesn’t figure in there, yet there is another type of forging used to create some of the most highly stressed components on rockets, missiles, and aircraft as well as the more mundane ironwork of your garden fence. Drop forging allows reproducible shapes to be forged while maintaining tight control over the metallurgical properties of the finished product, exactly what is required for such high-performance applications.
The video below is a promotional film about drop forging in the aeronautical industry from the late 1950s, made for and about Wyman Gordon, still specialists in the field. With the charming optimism of the period and a very catchy title it goes into the detail of the plant, development, and quality control of a range of parts for the missiles and rockets of the day, and along the way shows the cutting edge of machine tooling in the days before CNC. A whole Periodic Table of metals are forged with an expertise probably not seen in many other places in the world.
There are also some sights you’d never see in today’s safety culture, for example a running press with men darting in to adjust the position of a forging while it is still moving. It’s not a short video, but definitely worth watching all the way through.
Thermal imaging cameras are objects of desire for hackers and makers everywhere, but sadly for us they can be rather expensive. When your sensor costs more than a laptop it puts a brake on hacking.
All that has now changed though with this board. It features the Grid-EYE sensor itself, an Atmel ATSAM-D21G18A microcontroller, and onboard Bluetooth, but has an interesting feature that, as well as being a standalone device, can be used as an Arduino shield. A full range of APIs are provided, and the code is BSD licensed.
This module is not the highest-spec thermal imaging camera on the market by any means, after all it has a resolution of only 64 pixels in an 8×8 grid. But its affordability and easy availability should trigger a fresh crop of thermal camera projects in our community, and we applaud that.
You might expect that sourcing live algae would be as simple as scraping up a bit of green slime from a nearby pond, but that yields an uncertain mix of species. [Severin] wanted Chlorella algae for his experiment because its high fat content makes it suitable for biodiesel experiments, so had to source his culture from an aquatic shop.
The reactor takes the form of a spiral of transparent plastic tube surrounding a CFL lamp as a light source, all mounted on a lasercut wooden enclosure housing a pump. A separate glass jar forms a reservoir for the algal-rich water. He does not mention whether or not he adds any nutrient to the mix.
The little board that has at times seemed so plagued with delays as to become the Duke Nukem Forever of small computers has finally shipped. A million or so British seventh-grade schoolchildren and their teachers will today start receiving their free BBC micro:bits.
Announced early last year, the plan was to rekindle the learning of code in schools through handing out a powerful and easy to program small computer to the students. The hope is that it will recapture the spirit of the 1980s, when school computing meant programming Acorn’s BBC Micro rather than learning how to use Microsoft Word.
Sadly the project has been delayed multiple times, the original target of last October was missed, and a revised estimate from January suggested they might ship at half-term (about four weeks ago). With only a few days to go before the Easter school holidays the kids will have to try them out at home, but at least they’re arriving. Continue reading “British Kids Finally Get Their Micro:Bits”→
As a fresh-faced electronic engineering student while the first Gulf War was raging in a far-off desert, I learned my way through the different families of 74 logic at a university in the North of England. 74LS was the one to use, the story went, because it’s quick and doesn’t use much power. At the time, there was an upstart on the scene: 74HC. Now that’s really quick. New. Exotic, even.
Thus an association was formed, when you want a quick logic function then 74HC is the modern one to go for. It could have been a lifelong love affair, but over twenty years, after many factors of speed increases and some RF tricks with gates we wouldn’t have dreamed of back then, it’s over. There is a whole world of newer logic families to choose from, and while HC is still good at what it does, it’s well past time to admit that it may just have been superseded.
40673s, probably now worth more by weight than anything else on four legs. (Thanks are due to [Brandon Dunson] and Tanner Electronics) A tendency to cling to the past with logic families is pretty harmless. Like [Adam Fabio]’s TIP power transistors they’re pretty cheap, still very much in production, and still do most jobs demanded of them excellently. But what prompted this piece was a far more egregious example of an old component still being specified: the RCA 40673 dual-gate MOSFET. Launched in the mists of time when dinosaurs probably still roamed the earth, this static-sensitive four-pin TO72 found a home in a huge variety of RF amplifiers, oscillators, and mixers. It worked well, but as you might expect better devices came along, and the 40673 was withdrawn some time in the 1980s.
Unfortunately, nobody seems to have told a section of the amateur radio community about the 40673’s demise. Or perhaps nobody’s told them that many scrap analogue TV tuners of a certain age will yield a perfectly good newer replacement for free. Because even today, thirty years after the 40673 shuffled off this mortal coil, you can still find people specifying it. If you have a stash of them in your junk box, they’re worth a small fortune, and yours could be the bench with the throng of people at the next ham radio convention.
A different but equally annoying manifestation of the phenomenon comes when the device everyone likes to specify is not very old and very much still in production, but the designer hasn’t taken the time required to check for a cheaper alternative. Nobody ever got fired for buying IBM, they say, but perhaps they should be fired for specifying an AD8307 logarithmic amplifier in an amateur radio power meter. Don’t take this the wrong way, it’s a beautiful chip and probably a lot of work at Analog Devices has gone into laser-trimming resistors to make it perform to an extremely demanding specification. But eleven dollars for a chip? When a cursory search will turn up Maxim’s MAX9933 which does a perfectly good job in this application at well under two dollars? Someone isn’t doing their homework.
Sometimes there are components for which there are no perfect replacements. Germanium point-contact diodes, for example. 1N34As and OA91s are becoming like hen’s teeth these days, and though Schottky diodes can replace them in many applications, there are still a few places if you’re a radio person you’ll hanker for the original. There are suppliers on Alibaba who claim to manufacture 1N34s, but the pictures always look suspiciously like 1N4148s, and anyway who can find a home for a hundred thousand diodes? (Hang on, this is Hackaday. There will be someone out there with a hundred-thousand-diode project, you can count on it.)
OK, maybe germanium diodes are an edge case and the examples above have a radio flavour, but you get the picture. What the full-blown rant in the previous paragraphs has been building up to is this: a plea for designers to do their homework. Please try to design every project for the next two decades, and as though any extras in the component price come from your company’s bottom line. (We’ll make exceptions for building something for which the whole point is a retro circuit. An Apple I replica like the Mimeo 1 needs old logic chips for artistic purposes.)
Is there a vital electronic engineering skill that’s being lost here perhaps? Back when the Internet was the sole preserve of boffins and Tim Berners-Lee hadn’t yet plugged his hypertext ideas into it, we relied on catalogs. Big paper-bound books the size of telephone directories were our only window into the exciting world of electronic components. If you’re an American yours was probably from Radio Shack, but for most UK-based hackers and makers who couldn’t get their hands on a commercial account from RS or Farnell that meant the Maplin catalogue. Before they moved in a consumer-electronics direction, they were a component specialist whose catalogue with its distinctive spaceships on the cover could be bought at large newsstands.
It’s difficult to describe the impact of electronics catalogues in the ’70s and ’80s to someone who has known only the abundance of information from the WWW. These publications were our only window into the world of electronic components. They contained significant excerpts from semiconductor data sheets, and we read their wealth of information from cover to cover. We knew by heart what each device was capable of, and we eagerly devoured each new tidbit of information as it arrived.
In short, when we specified a component, we did so with a pretty good knowledge of all the components that were available to us.
By comparison, nowadays we can quickly buy almost any device or component in production from a multitude of suppliers. There are millions more devices available, and if RS or Farnell don’t have the part then Mouser or Digi-Key are sure to provide. The WWW allows us to find what we need in short order, and the miracle of global distribution means that we can have it delivered within 48 hours almost wherever we live.
CPC’s very aptly-named Big Book
Which means that all the new devices are available to us, but we’ve lost the ability to keep on top of them. We’ve become information rich, but knowledge poor. Printed catalogs still exist, but the sheer volume of information they contain forces brevity upon their entries and expands the size of the publication to the point at which it becomes an unwieldy work of reference. We therefore tend to stick with the devices and components we know, regardless of their cost or of whether they have been superseded, and our work is poorer for it.
We need to relearn the skill of inquisitiveness when it comes to the parts we use, and to rediscover the joy of just browsing, even if the medium is now a huge suppliers’ web site rather than a paper catalog. Otherwise we’ll still be looking at circuit diagrams containing 74LS logic and 40673 MOSFETs in the 2030s, and that can’t be a good thing!
There is of course also a slightly macabre alternative scenario. The highest online price we found for 40673s was over $30 each, so if a producer can make that kind of silly money then there’s a danger that RCA’s successors will see a business model in exhuming the corpse and re-animating it, thus ensuring that we’ll never be free of the undead. We need to make sure that doesn’t happen!
