These magical creatures crop up out of nowhere and fry your electronics or annoy your ear holes. Understanding them will doubtless save you money and hassle. The ground loop in a nutshell is what happens when two separate devices (A and B) are connected to ground separately, and then also connected to each other through some kind of communication cable with a ground, creating a loop. This provides two separate paths to ground (B can go through its own connection to ground or it can go through the ground of the cable to A and then to A’s ground), and means that current may start flowing in unanticipated ways. This is particularly noticeable in analog AV setups, where the result is audio hum or visible bars in a picture, but is also sometimes the cause of unexplained equipment failures. Continue reading “WTF Are Ground Loops?”→
Who said paddle wheels were just for leisurely riverboat cruises? [rctestflight] is smashing that image with a high-speed twist on the concept, using paddle wheels to propel a ground effect vehicle across water. In the video after the break, witness this blend of old and new as he tests various designs.
Over the past few years he’s worked on a series of ground effect vehicles which exploits the increased lift and reduced drag when flying close to a surface. Unlike full-sized counterparts, smaller RC models struggle to stay in this sweet spot due to less pronounced self-stabilizing feedback loops. This means a small scale vehicle tends to touch the water rather often, and bleeding a lot of momentum in the process.
He wanted to convert these losses into gains by giving the vehicles a boost of speed whenever it touches the water. It’s a popular trick with RC cars which will hydroplane for long distances as long as they can maintain speed. All the designs still required air propellers for takeoff and to help maintain speed. The final design didn’t really need the paddle wheel when the air and water was calm, but it definitely helped when things got choppy. He is already experimenting with different paddle designs but also plans to test some other types of surface drives.
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.
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.
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”→
This machine will hit a sweet spot between lever-type espresso machines that are like driving a manual without power steering, and those fully automated machines that squeeze all the fun out of playing barista but are easier on the joints.
Here’s how it works so far: a motor drives an electric gear pump that pumps the water through a heater. It’s a closed-loop system, so there’s a 3-way valve after the heater that keeps sending the water back until it’s deemed hot enough. Once that happens, the valve switches functions and begins to pump water through the group head and on to the coffee grounds.
[Ben] designed and milled a beautiful group head that’s designed to fit a La Pavoni portafilter and some other parts he already had on hand. Grab a coffee and watch it pull the first shot after the break, then stick around to see the milling and the drilling.
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.
