My Great-Great-Grandad, The Engineer Who Invented A Coffee Pot

May 1, 2023 by Jenny List 34 Comments

In the study of genealogy it’s common to find people who will go to great lengths involving tenuous cross-links to establish royalty or famous figures such as George Washington or William Shakespeare in their family tree. There’s no royal blood and little in the way of fame to be found in my family tree, but I do have someone I find extremely interesting. One of my great-great-grandfathers was a Scottish engineer called James R Napier, and though his Wikipedia entry hasn’t caught up with this contribution to 1840s technology, he was the inventor of the vacuum coffee pot.

He was born in Glasgow in 1821 and was the son of a successful shipbuilder, Robert Napier, into whose business he followed once he’d received his education. He’s probably most well known today for his work in nautical engineering and for inventing Napier’s Diagram, a method for computing magnetic deviance on compass readings, but he was also a prolific engineer and author whose name crops up in fields as diverse as air engines, weights and measures, drying timber, and even the analysis of some dodgy wine. The coffee percolator was something of a side project for him, and for us it’s one of those pieces of family lore that’s been passed down the generations. It seems he was pretty proud of it, though he never took the trouble to patent it and and thus it was left to others to profit from that particular invention.

Vacuum Coffee Pots: Impressive, But Slooow

Just what is a vacuum coffee pot, and what makes it special? The answer lies in the temperature at which it infuses the coffee. We take for granted our fancy coffee machinery here in the 21st century, but a century and a half ago the making of coffee was a much simpler and less exact process. Making coffee by simply boiling grounds in water can burn it, imparting bitter flavours, and thus at the time a machine that could make a better cup was seen as of some importance. Continue reading “My Great-Great-Grandad, The Engineer Who Invented A Coffee Pot” →

The World’s First Agricultural Right To Repair Law

April 29, 2023 by Jenny List 29 Comments

Long time readers will know that occasionally we mix up our usual subject matter with a dash of farm equipment. Usually the yellow and green variants that come from John Deere, as the agricultural manufacturer has become the poster child for all that is wrong in the fight for the right to repair. An old Deere is worth more than a nearly new one in many places, because for several years now their models have had all their parts locked down by DRM technologies such that only their own fitters can replace them. Now after a long legal fight involving many parties, the repair and parts company iFixit sound justifiably pleased as they announce the world’s first agricultural right to repair law being passed in the US state of Colorado. (Nitter)

This may sound like a small victory, and it will no doubt be followed by further rearguard actions from the industry as similar laws are tabled in other states. But in fact as we read it, with this law in place the game is de facto up for the tractor makers. Once they are required to release any access codes for the Coloradans those same codes will by extension be available to any other farmers, and though we’re guessing they won’t do this, they would be best advised to give up on the whole DRM idea and concentrate instead on making better tractors to fix their by-now-damaged brands.

It’s exciting news for everybody as it proves that right-to-repair legislation is possible, however since this applies only to agricultural machinery the battle is by no means over. Only when all machines and devices have the same protection can we truly be said to have achieved the right to repair.

We’ve reported on this story for a long time, here’s a previous piece of legislation tried in another state.

The Cheap And Available Microwave Playground

April 28, 2023 by Jenny List 11 Comments

There’s something of a mystique about RF construction at the higher frequencies, it’s seen as a Black Art only practiced by elite wizards. In fact, UHF and microwave RF circuitry is surprisingly simple and easy to understand, and given the ready availability of low-noise block downconverters (LNBs) for satellite TV reception there’s even a handy source of devices to experiment on. It’s a subject on which [Polprog] has brought together a handy guide.

A modern LNB has some logic for selecting one of a pair of local oscillators and to use vertical or horizontal polarization, but remains otherwise a very simple device. There’s an oscillator, a mixer, and an RF amplifier, each of which uses microwave transistors that can with a little care be repurposed. The page demonstrates a simple transmitter, but it’s possible to create more powerful devices by using the amplifier stage “in reverse”.

Meanwhile the oscillator can be moved by loading the dielectric resonators with PVC sleeving, and the stripline filters can even be modified with a fine eye for soldering and some thin wire. Keep an eye out in thrift stores and yard sales for old satellite dishes, and you can give it a go yourself. It’s a modern equivalent of the UHF tuner hacking enjoyed by a previous generation.

Op Amp Challenge: What’s Your Monitor’s Delay?

April 27, 2023 by Jenny List 12 Comments

In the days of CRT displays, the precise synchronization between source and display meant that the time between a video line appearing at the input and the dot writing it to the screen was constant, and very small. Today’s display technologies deliver unimaginable resolutions compared to the TV your family had in the 1970s, but they do so at the expense of all their signal processing imposing a much longer delay before a frame is displayed. This can become an issue for gamers, but also with normal viewing, because in some circumstances the delay can be long enough for it to be audible in a disconnect between film and soundtrack. It’s something [Mike Kibbel] has addressed with his video input delay meter, and it makes for a very interesting project.

At its heart is an FPGA, and in the video below the break he goes into great detail about its programming. It both generates a DVI output to drive the monitor and performs the measurement. The analog to digital converter side of the circuit is interesting, he has a photodiode and an op-amp driving a comparator to form a simple 1-bit converter. He takes us through the design process in detail, with such useful little gems as the small amount of hysteresis applied to the comparator.

There are probably many ways this project could have been implemented, but this one is both technically elegant and extremely well documented. Definitely worth a look!

Continue reading “Op Amp Challenge: What’s Your Monitor’s Delay?” →

Is An ADS-B Receiver The Solution For Drone Pilots?

April 27, 2023 by Jenny List 45 Comments

Over the years here at Hackaday, we’ve covered a range of stories about the ongoing panic surrounding drone flights. From plastic bags reported as drone incidents through to airports closed with no evidence of drones being involved, it’s clear that drone fliers are an embattled group facing a legal and aeronautical establishment that seems to understand little about them or their craft.

It sometimes seems to be a no-win situation for fliers, but perhaps [XJet] has something which might improve matters. He’s published a video showing off a portable ADS-B receiver which could be used by drone pilots to check for any aircraft in the vicinity and perhaps more importantly allow the drone community to take the moral high ground when problems occur.

The receiver isn’t particularly special, being a Raspberry Pi with LCD screen and an RTL-SDR receiver in a nice 3D printed enclosure. He says he’ll be publishing all software and build details in due course. But it’s the accessibility which makes it such a good idea, instead of being a very expensive safety device it’s a receiver that could probably be made with a less powerful Pi for under $100.

There is of course a flaw in the plan, that not all pilots are concerned enough for their safety to fit an ADS-B transponder to their aircraft, and so are invisible to both the thus-equipped drone pilot and air traffic control alike. This puts the onus on pilots to consider ADS-B an essential, but from the drone flier’s point of view we’d consider that a spotter should be part of their group anyway.

Curious what the fuss is about? Let us take you on a journey.

Continue reading “Is An ADS-B Receiver The Solution For Drone Pilots?” →

Vectrex Light Pen Works Without A Raster

April 26, 2023 by Jenny List 8 Comments

Sometimes the simplest of projects end up revealing the most interesting of things, as for example is the case with [Ryo Mukai]’s light pen for the Vectrex console. It’s an extremely simple device using an integrated light sensor with built-in Schmitt trigger, but for us the magic isn’t in the pen itself but in discovering how it worked with the Vectrex’s vector graphics.

Light pens were a popular accessory in the 8-bit computing days, offering a relatively inexpensive pointing device that gave your micro an even more futuristic feel. On most computers that used a raster-scanning TV display they simply picked up the flying dot on the screen as it passed the end of the pen, but the Vectrex with its display not scanning all of the screen at once needed a different approach.

This piqued our interest, and the answer to how it was done came from PlayVectrex. There was a target X on the screen which could be picked up with the pen, and when picked up it would surround itself with a circle. Crossing the dot as it flew round the circle would tell the console where the pen was, and the position would move to fit. For those of us who only saw a Vectrex in a shop window back in the day, mystery solved! We’ve placed a video showing the process below the break.

This isn’t the first light pen we’ve seen, they can even be connected to modern computers, too.

Continue reading “Vectrex Light Pen Works Without A Raster” →

Op Amp Contest: A Slice Of The ’70s

April 25, 2023 by Jenny List 7 Comments

The 1970s was a great time to be an electronics hobbyist, as a whole new world of analogue integrated circuits was coming down in price while new devices would appear to tempt the would-be constructor. Magazines and project books were full of simple circuits to do all manner of fun things, including many synthesizers and sound generators.

We’re reminded of those days by [Burkhard Kainka]’s triggered sound generator, which couples an op-amp timer to another op-amp phase shift oscillator to produce a sound described as “the unwilling meowing of a cat, which does not want to be disturbed“. Yes, we did make things like this back in the day.

The timer is triggered by a few millivolts on its input, which can come from a bit of mains hum or a flash of light to an LED operating as a photodiode. This provides enough DC voltage to the input of the phase shift oscillator to start oscillation, and in turn the oscillator drives a piezo speaker. It’s a fun little project, it shows that a microcontroller isn’t always needed to make something work, and maybe those of you without the experience of a 1970s childhood can learn a little bit of analogue magic from it. Need to know op-amps better? Read our primer!