Hackaday Links: August 18, 2024

August 18, 2024 by Dan Maloney 4 Comments

They’re back! The San Francisco autonomous vehicle hijinks, that is, as Waymo’s fleet of driverless cars recently took up the fun new hobby of honking their horns in the wee hours of the morning. Meat-based neighbors of a Waymo parking lot in the South Market neighborhood took offense at the fleet of autonomous vehicles sounding off at 4:00 AM as they shuffled themselves around in the parking lot in a slow-motion ballet of undetermined purpose. The horn-honking is apparently by design, as the cars are programmed to tootle their horn trumpets melodiously if they detect another vehicle backing up into them. That’s understandable; we’ve tootled ourselves under these conditions, with vigor, even. But when the parking lot is full of cars that (presumably) can’t hear the honking and (also presumably) know where the other driverless vehicles are as well as their intent, what’s the point? Luckily, Waymo is on the case, as they issued a fix to keep the peace. Unfortunately, it sounds like the fix is just to geofence the lot and inhibit honking there, which seems like just a band-aid to us.

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Digital Bike Horn Will Play Custom Sounds, Please Be Tasteful

December 23, 2023 by Lewin Day 19 Comments

When you’re out riding your bike, a horn can be a useful warning device to other road users and pedestrians alike. It can also be a source of fun and amusement, or annoyance, depending on the sounds it makes and how you use it. For the ultimate flexibility, you might like this digital bicycle horn that offers customizable sounds, as developed by [gokux].

The build has attractive two-tone components, consisting of a button pad for playing four sounds, and a sound module with a 3 watt speaker and battery pack. A Seeed Studio XIAO SAMD21 is the heart of the operation, with the microcontroller paired with a DFPlayer Mini which handles sound duties. When one of the four buttons is pressed, the microcontroller loads the relevant sound off an SD card, and plays it out over the speaker. For power, the build uses a lithium rechargeable battery with a healthy 1200 mAh capacity, which can be readily recharged thanks to a TP4056 charger module with a USB-C port.

It’s a nifty little build, and we love the Metal Gear Solid sounds. Though, we do wonder just how audible that 3 watt speaker is. If it proves inadequate, you could always step up to a much larger driver paired with a hefty audio amp if you so desire.

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Custom Car Horn Makes Many Sounds

July 9, 2021 by Lewin Day 29 Comments

A regular car horn is fine, but lacks finesse for more subtle communication. For example, some car horns aren’t particularly adept at short indicatory honks, and can only blare loudly regardless of the situation. For a fancier solution, [Tom Hammond] whipped up a custom car horn capable of playing a wide variety of sounds.

The system uses the Adafruit Audio FX board. This is a unique part, which is designed to enable people to build sound-based projects without the need for a microcontroller or any other similar hardware. Instead, the device can be connected to a computer over USB in mass storage mode, and its 16MB in-built memory can be loaded with sound files. It then plays these when buttons are pressed, hooked up to its 11 trigger inputs.

The Audio FX board has its output hooked up to a 120W amplifier, which then feeds into a pair of 15W PA-style horns. These are incredibly loud devices, though lack bass, so they’re really only good for throwing low-quality sound out in a noisy environment. For a car horn, that’s perfect.

The result is that [Tom] can press a number of buttons on his dash to play different sounds, from courtesy honks to animal noises and obnoxious sound effects. The great thing is that the sounds in question can be easily customized to the user’s tastes. [Tom] also deserves a tip of the hat for explaining in great detail how to actually install the project in the average car.

We don’t often see car horns around these parts, though they do make for an awfully loud alarm clock. If you’ve got your own nifty car accessories that you’re cooking up, be sure to drop us a line!

Probe The Galaxy On A Shoestring With This DIY Hydrogen-Line Telescope

September 29, 2019 by Dan Maloney 6 Comments

Foil-lined foam insulation board, scraps of lumber, and a paint-thinner can hardly sound like the tools of a radio astronomer. But when coupled with an SDR, a couple of amplifiers, and a fair amount of trial-and-error tweaking, it’s possible to build your own hydrogen-line radio telescope and use it to image the galaxy.

As the wonderfully named [ArtichokeHeartAttack] explains in the remarkably thorough project documentation, the characteristic 1420.4-MHz signal emitted when the spins of a hydrogen atom’s proton and electron flip relative to each other is a vital tool for exploring the universe. It lets you see not only where the hydrogen is, but which way it’s moving if you analyze the Doppler shift of the signal.