A Line Follower With No Brains

April 19, 2022 by Jenny List 26 Comments

A line follower is a common project for anyone wishing to make a start in robotics, a small wheeled device usually with some kind of optical sensor which allows it to follow a line drawn on the surface over which it runs. In most cases they incorporate a small microcontroller or perhaps an analogue computer which supplies power and steering control, but as the Crayon Car from [Greg Zumwalt] demonstrates, it’s possible to make a line follower without any brains at all.

This seemingly impossible feat is achieved thanks to the line and road surface, it runs on a piece of paper over which the line is drawn with a crayon. The robot has a single straight-line drive wheel at one end and a pair of driven rollers at 90 degrees to each other at the other end, with the magic happening due to the difference in friction between paper and crayon. The robot follows a circular track with no problem, and while we can see it’s not without flaws we doubt it would be possible to make a simpler follower.

Sharp-eyed readers will have noticed that this is not the first line follower we’ve shown you which claims to have no brains, but we’d claim that since the previous machine had an analogue circuit, this one is a more worthy contender to the crown.

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Bare Metal Gives This Pi Some Classic Synths

April 19, 2022 by Jenny List 18 Comments

We’re used to seeing the Raspberry Pi crop up in a wide range of the projects we show you here, but it’s fair to say that they usually feature some sort of operating system. There’s another way to use a Pi, more akin to using a microcontroller such as the Arduino: by programming it directly, so-called bare-metal programming. MiniDexed is an example, and it copies a classic Yamaha professional synthesiser of the 1980s, by emulating the equivalent of eight of the company’s famous DX7 synthesisers in one unit. It takes almost any Pi, and with the addition of an audio board, a rotary encoder, and an LCD display, makes a ready-to-go unit. Below the break is a video of it in operation.

It’s fair to say that we’re not experts in Raspberry Pi bare metal programming, but it’s worth a diversion into the world of 1980s synthesisers to explore the DX7. This instrument was a staple of popular music throughout the 1980s and was a major commercial success for Yamaha as an affordable FM synthesiser. This was a process patented at Stanford University in the 1970s and subsequently licensed by the company, unlike other synths of the day it generated sound entirely digitally. It’s difficult to overestimate the influence of the DX7 as its sound can be heard everywhere, and it’s not impossible that you own a Yamaha FM synth even today if you have in your possession a sound card.

Curious about the DX7? Master chip-reverse-engineer [Ken Shirriff] exposed its secrets late last year.

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The 555 Gives The CarolinaCon Badge Life

April 17, 2022 by Jenny List 1 Comment

For the electronic badge enthusiast, these last two years have seen something of a famine. While the pandemic may not be over yet, we’re learning to live with it in 2022, and there’s the prospect of a flush of new badges even if not all events are in-person yet. First to reach us is the Carolinacon Online 2 badge, a fairly simple affair which naturally has us pleased as punch because it incorporates the only chip that’s guaranteed to get you through the semiconductor shortage, an NE555 timer. It’s got everything, a flashing LED, and, well, that’s it because with the best will in the world a 555 is no powerhouse on its own. As a memento and a way to support the event it fits the bill, but it’s fair to say that this is no electronic tour de force.

Carolinacon Online 2 launches on Friday 29th of April, and features a schedule of talks and a set of merch including the badge. If you’re thinking of previous Carolinacon badges, this event has always taken the simple-but-effective route. The version they produced in 2021 for example had a hidden message behind the silkscreen, revealed through clever placement of LEDs controlled by an ATtiny microcontroller.

Can You Help Solve The Mystery Of This 1930s TV?

April 16, 2022 by Jenny List 23 Comments

84 years ago, a teenager built a TV set in a basement in Hammond, Indiana. The teen was a radio amateur, [John Anderson W9YEI], and since it was the late 1930s the set was a unique build — one of very few in existence built to catch one of the first experimental TV transmitters on air at the time, W9XZV in Chicago. We know about it because of its mention in a 1973 talk radio show, and because that gave a tantalizing description it’s caught the interest of [Bill Meara, N2CQR]. He’s tracking down whatever details he can find through a series of blog posts, and though he’s found a lot of fascinating stuff about early TV sets he’s making a plea for more. Any TV set in the late ’30s was worthy of note, so is there anyone else out there who has a story about this one?

The set itself was described as an aluminium chassis with a tiny 1″ CRT, something which for a 1930s experimenter would have been an expensive and exotic part. He’s found details of a contemporary set published in a magazine, and looking at its circuit diagram we were immediately struck by how relatively simple the circuit of an electrostatically-deflected TV is. Its tuned radio frequency (TRF) radio front end is definitely archaic, but something that probably made some sense in 1939 when there was only a single channel to be received. We hope that [Bill] manages to turn up more information.

We’ve covered some early TV work here not so long ago, but if you fancy a go yourself it’s not yet too late to join the party.

Home Made Stirling Engines From Expedient Materials

April 13, 2022 by Jenny List 28 Comments

Many of us have read about Stirling engines, engines which form mechanical heat pumps and derive motion from the expansion and contraction of a body of air. A very few readers may have built one, but for many they remain one of those projects we’d rather like to try but never quite have the inclination. The YouTube channel of [Geral Na Prática] should provide plenty of vicarious enjoyment then, with the construction of a range of Stirling engines from commonly available materials. We have Coke cans, PVC pipe, and nebuliser cartridges forming pistons and cylinders, with wire wool serving as a regenerative heat store. The latest video is below the break, an amazing 10-cylinder rotary device.

The Stirling engine is perhaps the quintessential example of a device whose time never came, never able to compete in power and efficiency with first steam engines and then internal combustion engines, it has over the years been subject to a variety of attempted revivals. Today it has appeared variously in solar power projects and in NASA’s hypothetical off-world power plants, and will no doubt continue to be promoted as an alternative energy conversion mechanism. We’ve featured many working model Stirling engines in our time and even done a longer investigation of them, but sadly we’ve yet to see a story involving a practical version.

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Ask Hackaday: Is It Time For Waste Heat And Cold Area Heating To Shine?

April 12, 2022 by Jenny List 82 Comments

It’s difficult to escape the topic of energy supply at the moment, with the geopolitical situation surrounding the invasion of Ukraine leaving the natural gas supply to an entire continent in jeopardy. Fortunately we’re watching the green shoots of an early spring here in the Northern hemisphere so the worst of the winter weather is behind us, but industrial customers can take no such solace from the season and will have to weather whatever price hikes are to come. Every alternative idea for energy supply is on the table, and with the parallel imperative of decarbonising the economy this goes beyond the short term into a future without so much need to rely on gas.

The Future is Cloudy

A district heating plant in Vienna, Austria. Joadl, CC BY-SA 3.0 AT

A collaboration between a Finnish district heating network and Microsoft caught our eye because the location of a new data centre for the tech giant was chosen specifically to supply waste heat to the network, rather than releasing it to the environment. It’s not uncommon at all for European cities to use district heating networks but they are normally supplied by waste incinerators, boilers, or combined heat and power stations. The use of data centre waste heat is a novelty, as is in particular the siting of the data centre being dictated by the network.
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This Chariot Is Pulled By A Team Of Motorcycles

April 11, 2022 by Jenny List 21 Comments

We’re fans of unusual forms of transport here, so when we saw an article featuring a home-made motorcycle chariot we knew we had to share it with you. You’ll probably notice it comes from the keyboard of our colleague [Lewin Day] as he moonlights writing for The Drive, and he’s brought along a lot of context and history to the dual-Husqvarna chariot built by [Jack Field].

The machine itself is a chariot in the ancient Roman fashion, a two-wheeled platform on which the rider stands and holds the reins. Instead of a team of horses though there is the aforementioned pair of Husqvarna motorcycles, and a pair of rods to their handlebars with throttle and brake controls take the place of reins. It’s fair to say that this might not be the least hazardous of conveyances, but it appears both rideable and controllable, and will appear at motorcycle shows. truth be told we’d like to have a go ourselves, but since it’s in Australia we think there’s little chance. Unexpectedly the motorcycle chariot is not a new idea, with their being used for full-scale races back in the 1930s. There’s a trip into that world with some exciting but lethal-looking racing action to view, but it seems that these machines exist here in 2022 mostly for show.

This isn’t the first machine operated by reins we’ve brought you, how about a rein-operated tractor?