Modern In-Circuit Emulator For The 6809

July 19, 2024 by Alexander Rowsell 12 Comments

The Motorola 6809, released in 1978, was the follow-up to their 6800 from four years earlier. It’s a powerful little chip with many 16-bit features, although it’s an 8-bit micro at heart. Despite its great improvements over the 6800, and even technical superiority over the Z80 and 6502 (hardware multiply, for example!), it never reached the same levels of success that those chips did. However, there are still some famous systems, such as the TRS-80 Colour Computer, which utilized the chip and are still being hacked on today. [Ted] is clearly a fan of the 6809, as he used a Teensy 4.1 to create a cycle-exact, drop-in 6809 emulator!

A small interposer board rearranges the Teensy pinout to match the 6809, as well as translating voltage levels from 3.3V to 5V. With careful design, the Teensy matches the cycle diagrams in the Motorola datasheet precisely, and so should be able to run any applications written for the chip! A great test was booting Extended Colour BASIC for the TRS-80 CoCo 2 and running some test BASIC programs. Any issues with opcode decoding or timing would certainly be exposed while running an interpreted language like BASIC. After this successful test, it was time to let the Teensy’s ARM Cortex-M7 rip and see what it could do.

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The Continuing Venusian Mystery Of Phosphine And Ammonia

July 19, 2024 by Maya Posch 18 Comments

The planet Venus is in so many ways an enigma. It’s a sister planet to Earth and also within relatively easy reach of our instruments and probes, yet we nevertheless know precious little about what is going on its surface or even inside its dense atmosphere. Much of this is of course due to planets like Mars getting all the orbiting probes and rovers scurrying around on its barren, radiation-blasted surface, but we had atmospheric probes descend through Venus’ atmosphere, so far to little avail. Back in 2020 speculation arose of phosphine being detected in Venus’ atmosphere, which caused both excitement and a lot of skepticism. Regardless, at the recent National Astronomy Meeting (NAM 2024) the current state of Venusian knowledge was discussed, which even got The Guardian to report on it.

In addition to phosphine, there’s speculation of ammonia also being detectable from Earth, both of which might be indicative of organic processes and thus potentially life. Related research has indicated that common amino acids essential to life on Earth would be stable even in sulfuric droplets like in Venus’ atmosphere. After criticism to the original 2020 phosphine article, [Jane S. Greaves] et al. repeated their observations based on feedback, although it’s clear that the observation of phosphine gas on Venus is not a simple binary question.

The same is true of ammonia, which if present in Venusian clouds would be a massive discovery, which according to research by [William Bains] and colleagues in PNAS could explain many curious observations in Venus’ atmosphere. With so much uncertainty with remote observations, it’s clear that the only way that we are going to answer these questions is with future Venus missions, which sadly remain rather sparse.

If there’s indeed life on Venus, it’ll have a while longer to evolve before we can go and check it out.

Desiccants, Tested Side By Side

July 19, 2024 by Jenny List 39 Comments

We’re so used to seeing a little sachet of desiccant drop out of a package when we open it, that we seldom consider these essential substances. But anyone who spends a while around 3D printing soon finds the need for drying their filament, and knowing a bit about the subject becomes of interest. It’s refreshing then to see [Big Clive] do a side-by-side test of a range of commonly available desiccants. Of silica gel, bentonite, easy-cook rice, zeolite, or felight, which is the best? He subjects them to exactly the same conditions over a couple of months, and weighs them to measure their efficiency in absorbing water.

The results are hardly surprising, in that silica gel wins by a country mile. Perhaps the interesting part comes in exploding the rice myth; while the rice does have some desiccant properties, it’s in fact not the best of the bunch despite being the folk remedy for an immersed mobile phone.

Meanwhile, this isn’t the first time we’ve looked at desiccants, in the past we’ve featured activated alumina.

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Watch This RC Jet Thrust System Dance

July 19, 2024 by Donald Papp 8 Comments

An EDF (electric duct fan) is a motor that basically functions as a jet engine for RC aircraft. They’re built for speed, but to improve maneuverability (and because it’s super cool) [johnbecker31] designed a 3D-printable method of adjusting the EDF’s thrust on demand.

Before 3D printers were common, making something like this would have been much more work.

The folks at Flite Test released a video in which they built [john]’s design into a squat tester jet that adjusts thrust in sync with the aircraft’s control surfaces, as you can see in the header image above. Speaking of control surfaces, you may notice that test aircraft lacks a rudder. That function is taken over by changing the EDF’s thrust, although it still has ailerons that move in sync with the thrust system.

EDF-powered aircraft weren’t really feasible in the RC scene until modern brushless electric motors combined with the power density of lithium-ion cells changed all that. And with electronics driving so much, and technology like 3D printers making one-off hardware accessible to all, the RC scene continues to be fertile ground for all sorts of fascinating experimentation. Whether it’s slapping an afterburner on an EDF or putting an actual micro jet engine on an RC car.

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How Ten Turn Pots Are Made

July 19, 2024 by Al Williams 5 Comments

It is easy to think of a potentiometer as a simple device, but there are many nuances. For example, some pots are linear — a change of a few degrees at the low end will change the resistance the same amount as the same few degrees at the high end. Others are logarithmic. Changes at one end of the scale are more dramatic than at the other end of the scale. But for very precise use, you often turn to the infamous ten-turn pot. Here, one rotation of the knob is only a tenth of the entire range. [Thomas] shows us what’s inside a typical one in the video below.

When you need a precise measurement, such as in a bridge instrument, these pots are indispensable. [Thomas] had a broken one and took that opportunity to peer inside. The resistor part is a coil of wire wound around the inside of the round body. Unsurprisingly, there are ten turns of wire that make up the coil.

The business end, of course, is in the rotating part attached to the knob. A small shuttle moves up and down the shaft, making contact with the resistance wire and a contact for the wiper. The solution is completely mechanical and dead simple.

As [Thomas] notes, these are usually expensive, but you can — of course — build your own. These are nice for doing fine adjustments with precision power supplies, too.

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An image of a man in glasses in a circle placed on a black background. The title "Pierce Nichols: Teaching Robots to Sail" is on white lettering in the bottom left corner.

Supercon 2023: [Pierce Nichols] Is Teaching Robots To Sail

July 19, 2024 by Navarre Bartz 12 Comments

Sailing the high seas with the wind conjures a romantic notion of grizzled sailors fending off pirates and sea monsters, but until the 1920s, wind-powered vessels were the primary way goods traveled the sea. The meager weather-prediction capabilities of the early 20th Century spelled the end of the sailing ship for most cargo, but cargo ships currently spend half of their operating budget on fuel. Between the costs and growing environmental concerns, [Pierce Nichols] thinks the time may be right for a return to sails.

[Nichols] grew up on a sailing vessel with his parents, and later worked in the aerospace industry designing rockets and aircraft control surfaces. Since sailing is predominantly an exercise in balancing the aerodynamic forces of the sails with the hydrodynamic forces acting on the keel, rudder, and hull of the boat, he’s the perfect man for the job.

While the first sails developed by humans were simple drag devices, sailors eventually developed airfoil sails that allow sailing in directions other than downwind. A polar diagram for a vessel gives you a useful chart of how fast it can go at a given angle to the wind. Sailing directly into the wind is also known as being “in irons” as it doesn’t get you anywhere, but most other angles are viable.

After a late night hackerspace conversation of how it would be cool to circumnavigate the globe with a robotic sailboat, [Nichols] assembled a team to move the project from “wouldn’t it be cool” to reality with the Pathfinder Prototype. Present at the talk, this small catamaran uses two wing sails to provide its primary propulsion. Wing sails, being a solid piece, are easier for computers to control since soft sails often exhibit strange boundary conditions where they stop responding to inputs as expected. Continue reading “Supercon 2023: [Pierce Nichols] Is Teaching Robots To Sail” →

Hackaday Podcast Episode 280: TV Tubes As Amplifiers, Smart Tech In Sportsballs, And Adrian Gives Us The Fingie

July 19, 2024 by Dan Maloney 3 Comments

Despite the summer doldrums, it was another big week in the hacking world, and Elliot sat down with Dan for a rundown. Come along for the ride as Dan betrays his total ignorance of soccer/football, much to Elliot’s amusement. But it’s all about keeping the human factor in sports, so we suppose it was worth it. Less controversially, we ogled over a display of PCB repair heroics, analyzed a reverse engineering effort that got really lucky, and took a look at an adorable one-transistor ham transceiver. We also talked about ants doing surgery, picking locks with nitric acid, a damn cute dam, and how to build one of the world’s largest machines from scratch in under a century. Plus, we answered the burning question: can a CRT be used as an audio amplifier? Yes, kind of, but please don’t let the audiophiles know or we’ll never hear the end of it.