A Low Voltage Tube Makes For A Handy Preamplifier

November 17, 2023 by 29 Comments

When most people think of tube circuits, the first thing that comes to mind is often the use of high-voltage power supplies. It wasn’t a given for tube circuits, though, as a range of low-voltage devices were developed for applications such as car radios. It’s one of these, an ECH83 triode-heptode, which [mircemk] has taken as the basis of an audio preamplifier circuit.

The preamp circuit is pretty simple, being a two-stage single-ended design using both halves of the tube. Between the two is a three-band tone control circuit as used in classic guitar amplifiers, making for a serviceable and easily achievable way to chase that elusive “valve sound.”

There is much discussion among audio enthusiasts about the supposed benefits of vacuum technology as opposed to transistors in an amplifier. Much of it centres around the idea that tubes distort in the even harmonics while semiconductors are supposed to do so in the odd harmonics. Still, we’d be inclined to spot a bit of snake oil instead and point to early transistor amplifiers simply being not very good compared to the tube amps of the day. That said, a well-made tube amplifier set-up will sound just as amazing as it always did, and since this one is paired with a matching power amp we wouldn’t say no to it ourselves.

If you fancy messing about with tubes for not a lot, there’s a cheap module for that.

Ham Radio Memes In The 1970s

November 11, 2023 by 12 Comments

If you have a fondness for old and unusual ham gear, [Saveitforparts] has a great video (see below) about a Robot slow scan receiver he found at a junk store.  Slow scan or SSTV is a way to send pictures via low-bandwidth audio, such as you often find on the ham bands. The idea is you take a picture, send some squeaks and blips over the air, and in about 8 or 10 seconds, a single frame of video shows up at the receiver. Hams aren’t the only ones who used it. The Apollo missions used an SSTV system in some cases, too.

I’ve been a ham radio operator for a very long time. When I first heard about SSTV, I thought it sounded cool that you could be talking to someone and then show them a picture of your station or your dog or your kids. But when I looked into it, the reality was far different. In the pre-internet days, SSTV-equipped hams hung out on a handful of watering hole frequencies and basically just sent memes and selfies to each other. Everyone would take turns, but there wasn’t really any conversation.

This actually still goes on, but the hardware isn’t a big deal anymore. The Robot in the video had to decode the signal from audio and store the image somehow. On old gear — some of it homebrew — it was simply persistent phosphor that would eventually fade, but, of course, eventually, images were stored in some form of digital memory. These days, you are likely to use a PC soundcard to both send and receive the necessary audio.

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Hands On With Boondock Echo

November 10, 2023 by 23 Comments

Perhaps no words fill me with more dread than, “I hear there’s something going around.” In my experience, you hear this when some nasty bug has worked its way into the community and people start getting whatever it is. I’m always on my guard when I hear about something like this, especially when it’s something really unpleasant like norovirus. Forewarned is forearmed, after all.

Since I work from home and rarely get out, one of the principal ways I keep apprised of what’s going on with public health in my community is by listening to my scanner radio. I have the local fire rescue frequencies programmed in, and if “there’s something going around,” I usually find out about it there first; after a half-dozen or so calls for people complaining of nausea and vomiting, you get the idea it’s best to hunker down for a while.

I manage to stay reasonably well-informed in this way, but it’s not like I can listen to my scanner every minute of the day. That’s why I was really excited when my friend Mark Hughes started a project he called Boondock Echo, which aims to change the two-way radio communications user experience by enabling internet-backed recording and playback. It sounded like the perfect system for me — something that would let my scanner work for me, instead of the other way around. And so when Mark asked me to participate in the beta test, I jumped at the chance.

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Forever Writing On Monofilament Fishing Line

November 8, 2023 by 50 Comments

Collectively, we have a long-term memory problem. Paper turns to mulch, dyes in optical disks degrade, iron oxides don’t last forever, and flash memories will eventually fade away. So what do you do when you want to write something down and make sure it’s around a couple of thousand years from now? Easy — just use something that even Mother Nature herself has trouble breaking down: plastic.

Specifically, fluoropolymer fishing line, which is what [Nikolay Valentinovich Repnitskiy] uses as a medium in his “Carbon Record” project. There’s not a lot of information in the repository, but the basic idea is to encode characters by nicking the fishing line along its length. The encoder is simple enough; a spool of fresh line is fed into a machine where a solenoid drives a sharpened bolt against the filament. This leaves a series of nicks that encode the ones and zeros of 255 ASCII characters. It looks like [Nikolay] went through a couple of prototypes before settling on the solenoid; an earlier version used a brushed motor to drive the encoder, but the short, rapid movements proved too much for the motor to handle. We’ve included a video below that shows the device encoding some text; sounds a little like Morse to us.

There seems to be a lot more going on with this device than the repo lets on; we’d love to know what the big heat sink on top is doing, for instance. Hopefully we’ll get more details, including how [Nikolay] intends to decode the dents. Or perhaps that’s an exercise best left to whoever finds these messages a few millennia hence.

2G Or Not 2G, That Is The Question

November 8, 2023 by 66 Comments

Since the very early 1990s, we have become used to ubiquitous digital mobile phone coverage for both voice and data. Such has been their success that they have for many users entirely supplanted the landline phone, and increasingly their voice functionality has become secondary to their provision of an always-on internet connection. With the 5G connections that are now the pinnacle of mobile connectivity we’re on the fourth generation of digital networks, with the earlier so-called “1G” networks using an analogue connection being the first. As consumers have over time migrated to the newer and faster mobile network standards then, the usage of the older versions has reduced to the point at which carriers are starting to turn them off. Those 2G networks from the 1990s and the 2000s-era 3G networks which supplanted them are now expensive to maintain, consuming energy and RF spectrum as they do, while generating precious little customer revenue.

Tech From When Any Phone That Wasn’t A Brick Was Cool

A 1990s Motorola phone
If this is your phone, you may be in trouble. Digitalsignal, CC BY-SA 3.0.

All this sounds like a natural progression of technology which might raise few concerns, in the same way that nobody really noticed the final demise of the old analogue systems. There should be little fuss at the 2G and 3G turn-off. But the success of these networks seems to in this case be their undoing, as despite their shutdown being on the cards now for years, there remain many devices still using them.

There can’t be many consumers still using an early-2000s Motorola Flip as their daily driver, but the proliferation of remotely connected IoT devices means that there are still many millions of 2G and 3G modems using those networks. This presents a major problem for network operators, utilities, and other industrial customers, and raises one or two questions here at Hackaday which we’re wondering whether our readers could shed some light on. Who is still using, or trying to use, 2G and 3G networks, why do they have to be turned off in the first place, and what if any alternatives are there when no 4G or 5G coverage is available? Continue reading “2G Or Not 2G, That Is The Question” →

Oh, The Places You’ll Go With Stop Motion Animation

November 5, 2023 by 5 Comments

Robots made of broken toy parts, stop-motion animation, and a great song to tie it all together were not on our bingo card for 2023, but the results are perfect. [Mootroidxproductions] recently released the official music video for I Fight Dragons 2019 song “Oh the Places You’ll Go”.

The song was written by lead vocalist [Brian Mazzaferri] with inspiration from the classic Dr. Seuss book. [Brian] wrote it for his newborn daughter, and we’re pretty sure it will hit any parent right in the feels.

[Mootroidxproductions] isn’t a parent themselves, but they expanded on the theme to create a video about sacrificing oneself to save a loved one. With a self deprecating wit, they take us through the process of turning broken Bionicle parts, bits of Gundam, Lego, and, armature wire to make the two robots in the film. He also explains how he converted garbage into sets, greebles, and lighting effects.

The robots had to be designed so that they could fulfill their roles in the film. From the size of their hands down to their individual walking gaits, he thought of everything. His encyclopedic knowledge of Bionicle parts is also on full display as he explains the origin of the major parts used to build “Little Blue” and “Sherman”

Click through the break for both the main video and the behind-the-scenes production.

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2023 Halloween Hackfest: Quoth The Raven, “Caww!”

October 31, 2023 by 5 Comments

Sometimes, projects start in somewhat unlikely places. This one began when [Istvan Raduly] scored a fake raven at a neighbor’s garage sale and decided to turn it into a thunder-and-lightning decoration that would frighten even the bravest trick-or-treater.

Get close enough to this raven and you’ll set off the PIR sensor, which triggers lighting and sound effects, including some spooky glowing and blinking red eyes, general cawing, and of course, thunder. The light comes from a whopping 10-watt, 12-volt power LED. This bird’s brain is an Arduino Nano, which is protected from the 12V supply with a boost converter. As you might expect, the sounds are on an SD card and played through a DF Player Mini.

Spookiness aside, our favorite part might be the absolutely lovely job that [Istvan] did decorating the raven’s base. Hiding electronics and hot glue is one thing, but this is above and beyond. Be sure to check it out after the break, both in the safety of the house, and outside in the scary darkness.

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