Putting a Car Horn on Your Bicycle!





Introduction: Putting a Car Horn on Your Bicycle!

About: I'm a full stack web developer focusing on security and privacy.

I'v found in my biking adventures, drivers are aloof, distracted and just plain blind to us little pieces of metal on the road.
I'v also found giving a little shout before a driver makes a right hand turn with out signaling is a great way to save your life, but i like my voice to not be raspy after running around town. This project started with a little 12 volt scooter horn that i ran off of 9 volts, and i found it just wasn't loud enough.

SO the car horn project was BORN!

enough from me, lets get on with it!

Step 1: Scavanging List

-One Car Horn (louder the better, test it out before buying. try scrap yards. i found mine under a friends house. Some are 12v some are 14v. I have not found a good way to test this other than hooking them up to batteries.)
-Battery Pack (For this demo i'm using 12 volts of AA batteries, i strongly suggest for permanent use to get something rechargeable. You can safely go to 14 volts with these horns and some horns need at least 14 to function. Lead acid batteries are too heavy for most but would work great, I'm getting some discarded laptop batteries in a week.)
-Push Button Switch (get something you can imagine triggering safely and be able to reach your breaks. Be sure the voltage works for what you're doing.)
-Electrical Wire (I'm using 18 gauge to do the hook up, any will do.)
-Plugs and Hookups (to take the battery pack with you when you park, or to recharge it. Every horn is different to hook it up.)
-Hardware (anything to attach the horn to the bike.)

Things you should have:
-A Basic soldering set with solder, an iron and clean working space
-Multimeter, so you can test voltage with out blowing the horn every time
-Time, not a lot of it but a sufficient amount.

Step 2: Soldering the Battery Pack

first you want to solder the battery pack to the wire that will go to the first plug, i'm using a 9v snap to snap to the pack.

DON'T SOLDER DIRECTLY TO THE BATTERY! come up with something to snap, or clip on there. if worse comes to worse, use alligator clips. if the battery has tabs, use a tab connector.

when you are done, hook up the battery and test the voltage. If its good, you're good!

Step 3: Soldering to the Plug

now to make it easy to remove, lets solder it a plug. I had these wheel chair hookups that are androgynous, but any hookup will do. this will make it so we can bolt the horn on the bike and take the battery with us when we want to charge it.

Step 4: Adding a Switch

on the other end of the plug that attaches to the horn, we want a push button switch so we can trigger it whenever we want!

just cut the wire, solder in the switch and tape it up.



Once everything is soldered, hook it up and honk it!

Once it's done, clean up the wiring with shrink tubing or electrical tape. and put it on your bike!

Cars will finally give you the respect you deserve!

If people have suggestions for improvement or videos of their bikes carrying a horn please comment!

Watch the movie for the sound example!

Step 6: Updates

So since the original writing of this article i have made some adjustments.

-The switch i initially used was all plastic, i broke when i got in a bike accident (during SF critical mass). i replaced the switch with an all metal component, it's now awesome

-the battery pack is now covered by an extra plastic box i had laying around. i really want to get a rechargable pack from this site: http://www.batteryspace.com/index.asp?PageAction=VIEWCATS&Category=883

other than that, it's awesome!



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    Sure, get a pair of horns, a hose with the right connectors, and a tank with a capacity of as many gallons of air as you want to be able to blast it regulated to 150psi (or whatever the horns you get require). If you want a good amount of blasting get a trailer and coiled hose if you plan on mounting the horn on the handlebars. You could even haul a gas-powered compressor that can get up to 150psi (~$650 new at Northern tool).

    how many amp hours would you recommend? Weight isn't a huge issue for me. Would a 5ah SLA be overkill? How long would it last. I'm sure it depends on the horn but I'm just trying to get an idea.

    Hi! Great project!! How long does it last? Thanks a lot from Argentina.

    I havE two 9V rechargeable batteries with me .can I use it with a12V horn ? Plzzz help

    1 reply

    9v will make the horn sound but it will be less loud. 9v will not damage a 12v horn.

    Good idea and build but builders beware of AC-horns.

    11 replies

    Why would there be an ac horn in a car that runs off of a battery? Batteries only produce dc current.

    True for most later models (i.e post 1975), earlier most cars used AC-generators and AC throughout the car (exception is VW type1). In those cars the horns would often not be self-oscillating but use the AC to oscillate the membrane.
    However you youngster will probably never run into that but if you do work on an older car without radio, keep it in mind.

    Have I mentioned I'm kind of a know-it-all-nerd?

    This it the issue I came across, apparently the cheaper bike horns tend to be AC to I connected my batteries and just got a click :(

    1. Anyone younger than me 2. Someone who tends to use newer technology than me 3. Even just anyone I feel like calling a youngster for no apparent reason 4. Someone who's never heard of some archaic thing I can think of regardless of relevance 5. Everyone whenever I decide to play old grumpy guy

    lol. So would an 18 year-old like myself be in your catagories? (sarcasm here) I take no offense, I just find it funny.

    He he, ofcourse. Why, when I was you age we didn't have cellphones and internets. We had to go to the library and hope they had a book about it and when we wanted to talk to someone we had to call them and hope they were at home. Oddly enough, we did have facebook for some reason. :D

    yeah, that's a bit weird. but one of these days, now that I got a better bike, I should try this. I know someone who has a bunch of parts lying around to try it out. He's always complaining that he can't use them anyway. (smiles at all the devious possibilities!!)

    Cars went from generators to alternators in the 60's. The generator cars I owned were DC (how would you recharge the battery with AC???).

    A rectifier of course.

    when have you found AC horns?