The FNIRSI HRM-10 Internal Resistance Meter

October 17, 2024 by 16 Comments

Occasionally, we find fun new electronic instruments in the wild and can’t resist sharing them with our readers. The item in question is the FNIRSI HRM-10 Internal resistance meter, which we show here being reviewed by [JohnAudioTech].

So what does it do, and why would you want one? The device is designed to measure batteries so you can quickly determine their health. Its operating principle also allows it to do a decent job of measuring low-resistance parts, which is not necessarily as easy to achieve with the garden variety multimeter, especially the low-end ones. We reckon it would be useful in the field for checking the resistance of switches and relays, possibly in automotive or industrial applications. The four-pin connector is needed because there are two wires per probe, making a Kelvin (also known as four-wire) connection.

Likely, the operating principle is to apply a varying load to the battery under test and then measure the voltage drop. The slope of the voltage sag vs load is a reasonable estimate of the resistance of the source, at least for the applied voltage range. The Kelvin connection uses one pair of wires to apply the test current from a relatively low-impedance source and the second pair to measure the voltage with a high input impedance. That way, the resistance of the probe wires can be calibrated out, giving a much more accurate measurement. Many lab-grade measurement equipment works this way.

Circling back to the HRM-10, [John] notes that it also supports limit testing, making it a helpful gauging tool for the workbench when sorting through many batteries. Data logging and the ability to upload to a computer completes the feature set, which is quite typical for this level of product now. Gone are the days of keeping a manual logbook next to the instrument stack and writing everything down by hand!

We’ve touched on measuring battery internal resistance before, but it was a while ago. Regarding Kelvin connections, here’s a quick guide and a hack upgrading a cheap LCR to support 4-wire probes.

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Mining And Refining: Mine Dewatering

October 17, 2024 by 9 Comments

From space, the most striking feature of our Pale Blue Dot is exactly what makes it blue: all that water. About three-quarters of the globe is covered with liquid water, and our atmosphere is a thick gaseous soup laden with water vapor. Almost everywhere you look there’s water, and even where there’s no obvious surface water, chances are good that more water than you could use in a lifetime lies just below your feet, and accessing it could be as easy as an afternoon’s work with a shovel.

And therein lies the rub for those who delve into the Earth’s depths for the minerals and other resources we need to function as a society — if you dig deep enough, water is going to become a problem. The Earth’s crust holds something like 44 million cubic kilometers of largely hidden water, and it doesn’t take much to release it from the geological structures holding it back and restricting its flow. One simple mineshaft chasing a coal seam or a shaft dug in the wrong place, and suddenly all the hard-won workings are nothing but flooded holes in the ground. Add to that the enormous open-pit mines dotting the surface of the planet that resemble nothing so much as empty lakes waiting to fill back up with water if given a chance, and the scale of the problem water presents to mining operations becomes clear.

Dewatering mines is a complex engineering problem, one that intersects and overlaps multiple fields of expertise. Geotechnical engineers work alongside mining engineers, hydrogeologists, and environmental engineers to devise cost-effective ways to control the flow of water into mines, redirect it when they can, and remove it when there’s no alternative.

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What Would It Take To Recreate Bell Labs?

October 17, 2024 by 45 Comments

It’s been said that the best way to stifle creativity by researchers is to demand that they produce immediately marketable technologies and products. This is also effectively the story of Bell Labs, originally founded as Bell Telephone Laboratories, Inc. in January 1925. As an integral part of AT&T and Western Electric, it enjoyed immense funding and owing to the stable financial situation of AT&T very little pressure to produce results. This led to the development of a wide range of technologies like the transistor, laser, photovoltaic cell, charge-coupled cell (CCD), Unix operating system and so on. After the break-up of AT&T, however, funding dried up and with it the discoveries that had once made Bell Labs such a famous entity. Which raises the question of what it would take to create a new Bell Labs?

As described in the article by [Brian Potter], one aspect of Bell Labs that made it so successful was that the researchers employed there could easily spend a few years tinkering on something that tickled their fancy, whether in the field of semiconductors, optics, metallurgy or something else entirely. There was some pressure to keep research focused on topics that might benefit the larger company, but that was about it, as the leadership knew that sometimes new technologies can take a few years or decades to come to fruition.

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Read All About It: The 2024 Supercon Site Is Live

October 17, 2024 by 4 Comments

With the 2024 Hackaday Supercon just a couple weeks away, we’re pleased to announce that the official site for the three-day event is now live!

On the brand-new Supercon page, you can find a listing of all of our fantastic speakers, the hands-on workshops, and perhaps most importantly, the schedule of when everything is happening. As always, Supercon is jam-packed with incredible content, so you’ll want to consult with the schedule to navigate your way through it. Don’t worry if it ends up that two talks you want to see are scheduled for the same time — we’ll be recording all of the talks and releasing them on the Hackaday YouTube channel, so you won’t miss out.

If you’re still on the fence, we do have a few tickets left at the time of this writing. All of the workshops are full at this point, but you can still get on the waiting list for a few of them just in case a spot opens up.

DIY Core Rope Memory Z80 Demonstrator Generating A Fibonacci Sequence

October 16, 2024 by 14 Comments

We’ve seen a few retro products using core rope memory, such as telephone autodiallers. Obviously, we’ve covered the Apollo program computers, but we don’t think we’ve seen a complete and functional DIY computer using core rope memory for program storage until now. [P-lab] presents their take on the technology using it to store the program for a Z80-based microprocessor demoboard, built entirely through-hole on a large chunk of veroboard.

For the uninitiated, core rope memory is a simple form of ROM where each core represents a bit in the data word. Each wire represents a single program location. Passing a wire through the core sets the corresponding bit to a logic 1, else 0. These wires are excited with an AC waveform, which is coupled to the cores that host a wire, passing along the signal to a pickup coil. This forms an array of rudimentary transformers. All that is needed is a rectifier/detector to create a stable logic signal to feed onto the data bus.

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Winamp Taken Down: Too Good For This Open Source World

October 16, 2024 by 58 Comments

If you picked today in your hackerspace’s sweepstake on when Winamp would pull their code repository, congratulations! You’re a winner! The source for the Windows version of the venerable music player was released on GitHub three weeks ago, and after some derision over its licence terms, a bunch of possible open source violations, and the inadvertent release of some proprietary third-party code, it’s been taken down. We’re sure that if you still have a burning desire to look at it then it won’t be too difficult to find a copy through your favorite search engine, leaving the question of what really just happened.

It’s fairly obvious that the owners of the code lacked some level of understanding of just what open source really is, based on their not-really-open licence and all those code leaks. They did back down on not allowing people to create forks, but it’s evident that they didn’t anticipate the reaction they got. So were they merely a bit clueless, or was it all just a publicity stunt involving a piece of software that’s now of more historical than practical interest? It’s possible we’ll never know, but the story has provided those of us sitting on the fence eating popcorn with some entertainment.

Module Makes Noisy Projects Easy

October 16, 2024 by 7 Comments

You want to add voice, music, or sound effects to your project. What do you do? Sure, it is easy enough to plug a Raspberry Pi or some other tiny computer, but that’s not always desirable from a power, space, or cost point of view. [Mellow_Labs] shows a module that makes it simple to add sound to any project. The little board is just big enough to house a speaker and doesn’t cost much. Check it out in the video below.

The device allows you to preload tracks as MP3 files. There are two ways to control it: via a serial port, or using a single pin that can accept commands like you might expect from a MP3 player, like play and next track.

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