Custom Car Horn Makes Many Sounds

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!

29 thoughts on “Custom Car Horn Makes Many Sounds

  1. Is this legal, most places in the US have noise ordinance laws. If you are using your horn, to avoid a collision you are exempt, but if you are using your horn for any other reason you can get a fat fine. Usually this means the neighbors all called the problem oriented police line, which means you were being an ass for a long time, but it happens.

    1. Suppose it depends on which state you live in… The are noise ordinances, but seem to be seldom enforced. There are plenty of those sub-woofer cars on the road, which should be criminal in traffic. Those driving them, with earplugs, should be jailed for driving impaired, like any fool driving drunk or on drugs. For car horns though, I don’t think there are restrictions on use. The PA speaker thing might be a little different. Maybe the Ice Cream Man needs a permit.

      This isn’t a new idea, probably isn’t any cheaper than a commercial product. Only difference is that you get to decide which sounds to put on it. The commercial units a pre-loaded, and don’t remember any that offered the option to add your own.

    2. Same happens here, if you toot to say “bye” or “hi” that’ll get you a fine. If you horn in rage, that to will get you a fine. But I would mind a bit of variety between the ‘beep, don’t merge into me’ and ‘beep, wake up and see the light is green’. I find the horn in my car is quite stiff and hard to get a polite beep out of (probably because it’s barely been pressed in 4 years, it’s still almost new lol)

    1. LOL I had a horn off a locomotive on my F650 4×4 and let’s just say I had a ton of fun at crossings and especially people texting while driving. No I didn’t cause any wrecks just stained underwear

  2. There was a comedian stand up bit ages ago that we need a horn that sort of does a loud cough, or an “ahem.” Like you’re at a light and it turns green and the person isn’t paying attention. A little “ahem” would be nice. A regular “hoooonk” is too aggressive, even if you try to micro-honk it.

  3. Post deleted (I think)
    There was a comedian saying that we need a horn that will sort of go “ahem” for, like, when you are stuck at a light and the person in front isn’t paying attention when it turns green.

  4. Luckily any multi-tone car horns are outlawed where I live.
    You can even get fined for making yanking the horn for any situation other then a traffic related emergency.

    And still there is the occasional idiot who starts blaring away at 4 o’clock in the morning with no better reason then to let the whole neighborhood know that he’s attempting to go home after a party.

  5. Rather than a car horn you should fit a device that emulates other types of engine noise – synchronised with your revs and ‘VCF’d’ with the engine vacuum.

    Imagine moving off from traffic lights like a locomotive, or revving like an F1 car???

    1. You mean like the stupid law in Europe that electric cars now have to make noises louder than modern combustion cars? That kind of motor-controlled noise is now “hype”.
      I hate every bit of it.

      1. Since I was almost run over by an electric that made an illegal right on red when I was crossing with a walk signal, I am all for it. I use my ears as a pedestrian, but when it’s silent, that doesn’t help. Luckily, I caught some motion out of the corner of my eye and was able to jump out of the way.
        I whole heatedly agree with the noise requirements and made darn sure my vision impaired friend could hear my Leaf. It only plays up to about 18 mph and I can barely hear it when in the car with the window down, so it’s not onerous.

      2. These laws make me laugh cos my Honda jazz can sneek up on people almost as well as my co-workers Tesla. Tesla’s aren’t quiet, they make road noise. I could always hear him pulling into my driveway when we carpooled and I’d be at the opposite end of the house too. Mean while I’ve scared the ever loving fecal matter out of people while cruising for a parking spot in my Jazz (“oh crap! There’s a car behind me”)

  6. “For example, some car horns aren’t particularly adept at short indicatory honks, and can only blare loudly regardless of the situation.”

    Yeah that’s my grand caravan. Too often a quick wake-up toot comes out either:
    a) silent, or
    b) “I will murder your ******* family”

    Back in the day I used to have a horn speaker attached to my CB radio (on the PA amp output) and I’d love to give people little words of encouragement. Got a lot of fingers with that one for some reason.

    1. I’ve often wished that modern ham radios would have that option for some subtle encouragement to other drivers. My wife thinks it would be a bad idea and I’d just get shot! (because Texas)

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