Solving Grounding Issues On Switch Audio

March 27, 2022 by Bryan Cockfield 32 Comments

Grounding of electrical systems is an often forgotten yet important design consideration. Issues with proper grounding can be complicated, confusing, and downright frustrating to solve. So much so that engineers can spend their entire careers specializing in grounding and bonding. [Bsilvereagle] was running into just this sort of frustrating problem while attempting to send audio from a Nintendo Switch into a PC, and documented some of the ways he attempted to fix a common problem known as a ground loop.

Ground loops occur when there are multiple paths to ground, especially in wires carrying signals. The low impedance path creates oscillations and ringing which is especially problematic for audio. When sending the Switch audio into a computer a loop like this formed. [Bsilvereagle] set about solving the issue using an isolating transformer. It took a few revisions, but eventually they settled on a circuit which improved sound quality tremendously. With that out of the way, the task of mixing the Switch audio with sources from other devices could finally proceed unimpeded.

As an investigation into a nuisance problem, this project goes into quite a bit of depth about ground loops and carrying signals over various transforming devices. It’s a great read if you’ve ever been stumped by a mysterious noise in a project. If you’ve never heard of a ground loop before, take a look at this guide to we featured a few years ago.

Know Audio: Mixtapes, Tape Loops, And Razor Blades

December 20, 2021 by Jenny List 16 Comments

In our no-nonsense journey through the world of audio technology we’ve so far have looked at digital audio and the vinyl disk recording. What’s missing? Magnetic tape, the once-ubiquitous recording medium that first revolutionised the broadcast and recording industries in the mid-20th-century, and went on to be a mainstay of home audio before spawning the entire field of personal audio. Unless you’re an enthusiast or collector, it’s likely you won’t have a tape deck in your audio setup here in 2021 and you’ll probably be loading your 8-bit games from SD card rather than cassette, but surprisingly there are still plenty of audio cassettes released as novelties or ephemeral collectables.

The Device That Made The Sound Of The Latter Half Of The 20th Century

"Like a travelling razor blade", a Blattnerphone steel-strip tape recorder at the BBC in 1937. Douglas Hallam, Jr., Public domain. — “Like a travelling razor blade”, a Blattnerphone steel-strip tape recorder at the BBC in 1937. Douglas Hallam, Jr., Public domain.

The first magnetic recordings were made directly on metal wires, but metal fatigues as it bends. By coating a flexible plastic tape in ferrous particles, the same simple technique of laying down an audio signal as variations in the magnetic field could be made smaller, lighter, and more robust. But the key to the format’s runaway success is the technical advancements that differentiate those 1950s machines from their wire recorder ancestors.

Whether it is a humble cassette recorder or a top-end studio multitrack, all tape recorders are very similar. There are two reels that hold the tape: the playback reel that houses the recording, and the take-up reel that stores the tape as it plays in the machine. The take-up reel is lightly driven to run faster than the tape speed, and the playback reel has a slight braking force to keep the tape under tension at all times. Continue reading “Know Audio: Mixtapes, Tape Loops, And Razor Blades” →

Hyperloop: Fast, But At What Cost?

December 9, 2020 by Lewin Day 162 Comments

When it comes to travelling long distances, Americans tend to rely on planes, while the Chinese and Europeans love their high speed rail. However, a new technology promises greater speed with lower fares, with fancy pods travelling in large tubes held at near-vacuum pressures. It goes by the name of Hyperloop.

Virgin Hyperloop recently ran the first-ever passenger test of a Hyperloop vehicle, reaching 100 mph on a short test track.

Spawned from an “alpha paper” put together by Elon Musk in 2013, the technology is similar to other vactrain systems proposed in the past. Claiming potential top speeds of up to 760 mph, Hyperloop has been touted as a new high-speed solution for inter city travel, beating planes and high speed rail for travel time. Various groups have sprung up around the world to propose potential routes and develop the technology. Virgin Hyperloop are one of the companies at the forefront, being the first to run a pod on their test track with live human passengers, reaching speeds of 100 mph over a short 500 meter run.

It’s an exciting technology with a futuristic bent, but to hit the big time, it needs to beat out all comers on price and practicality. Let’s take a look at how it breaks down.

Continue reading “Hyperloop: Fast, But At What Cost?” →

Ask Hackaday: With Landline Use In Decline, What’s To Be Done With The Local Loop?

October 12, 2020 by Dan Maloney 100 Comments

Walking is great exercise, but it’s good for the mind too: it gives one time to observe and to think. At least that’s what I do on my daily walks, and being me, what I usually observe and think about is the local infrastructure along my route. Recently, I was surprised to see a number of telephone company cabinets lying open next to the sidewalk. Usually when you see an open box, there’s a telephone tech right there, working on the system. But these were wide open and unattended, which I thought was unusual.

I, of course, took the opportunity to check out the contents of these pedestals in detail. Looking at the hundreds of pairs of brightly colored wire all neatly terminated and obviously installed and maintained at great expense, I was left wondering why someone would leave such a valuable asset exposed to the elements. With traditional POTS, or plain old telephone service, on the decline, the world may no longer have much use for the millions of miles of copper cable feeding back to telco central offices (COs) anymore. But there’s got to be something this once-vital infrastructure is still good for, leading me to ask: what’s to be done with the local loop?

Continue reading “Ask Hackaday: With Landline Use In Decline, What’s To Be Done With The Local Loop?” →

Homebrew Loop Antenna Brings The Shortwave World To You

April 12, 2020 by Dan Maloney 36 Comments

Radio may be dead in terms of delivering entertainment, but it’s times like these when the original social network comes into its own. Being able to tune in stations from across the planet to get fresh perspectives on a global event can even be a life saver. You’ll need a good antenna to do that, which is where this homebrew loop antenna for the shortwave radio bands shines.

To be honest, pretty much any chunk of wire will do as an antenna for most shortwave receivers. But not everyone lives somewhere where it’s possible to string up a hundred meters of wire and get a good ground connection, which could make a passive loop antenna like this a good choice. Plus, loops tend to cancel the electrical noise that’s so part of life today, which can make it easier to pull in weak, distant stations.

[Thomas]’s design is based on a length of coaxial cable, which should be stiff enough to give the loop some stability, like a low-loss RG-8 or RG-213. The coax braid and dielectric are exposed at the midpoint of the cable to create a feed point, while the shield and center conductor at the other ends are cross-connected. A 1:1 transformer is wound on a toroid core to connect to the feedpoint; [Thomas] calls it a balun but we tend to think it’s more of an unun, since both the antenna and feedline are unbalanced. He reports good results from the loop across the shortwave band.

The shortwave and ham bands are a treasure trove of information and entertainment just waiting to be explored. Check them out — you might learn something, and you might even stumble across spies doing their thing.

[via RTL-SDR.com]

Cesium Clock Teardown, Or Quantum Physics Playground

March 25, 2020 by Al Williams 20 Comments

Half the fun of getting vintage test equipment is getting to open it up. Maybe that’s even more than half of the fun. [CuriousMarc] got an HP 5061A Cesium clock, a somewhat famous instrument as the model that attempted to prove the theory of relativity. The reason? The clock was really the first that could easily be moved around, including being put on an airplane. You can watch the video below.

According to the video, you can simplify special relativity to saying that time slows down if you go fast — that is known as time dilation. General relativity indicates that time slows down with increasing gravity. Therefore, using airborne Cesium clocks, you could fly a clock in circles high up or fly at high speeds and check Einstein’s predictions.
Continue reading “Cesium Clock Teardown, Or Quantum Physics Playground” →