12 volt to 6 volt

I did a search of all of the forums and could not find anything near what I need. I purchased an antique 6volt horn and want to put it on my 12 volt car. I know the horn works as I have momentarily hooked up 12 volts to it but the wiring becomes very hot when I do this. Do I need a resistor or a voltage reducer and what kind of either would be appropriate?

Thanks for the suggestions. Where would I purchase a voltage regulator for this application?

radioshack would have it or a local electronic store will have it for sure.

you could build your own with 2 ops amps (one chip) and a few resistors, if interested email me and ill design the circuit for you.If you say "I already know how", don't ask me a single question.