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.
Step 5: HONK THAT HORN!!
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!