I just got my license thank God and wanna get my truck running and get me a nice loud horn goin so far I just thru in a wolo for giggles but I dont have the funds of getting a expensive set so im building pvc horns but with a metal trumpets off a flipped truck that was in the sticks (the actual horns were broke) I also wanna know how I can run a regular compressor on my battery and if anyone knows how to make a lanyard valve
Would really appreciate the help
When you say “regular compressor” , do you mean a mains power compressor (like a shop compressor)? If so, you may want to reconsider. To get 110 or 240 volts from a car, you’ll need an inverter. Even with a moderately powerful inverter you’ll have issues with amperage loads and so forth.
Consider how big a tank you’re going to install, then get a compressor to suit, otherwise you’re wasting your money. If funds are tight, something like a 2 gallon tank with a Viair 280C is not a bad starting point. Spending a bit more on your compressor will pay dividends later as it’s the hardest working component.
Now… a “lanyard valve” ? I’m guessing you want a truck type manual valve. Check on eBay for a Grover style air horn valve. They’re cheap, but not designed to flow huge amounts of air though. You’ll find that Manual Valves aren’t cheap, especially big flowing train horn types. There’s some cheaper copies of the Graham White style valves being sold at various places and you can rig up a pulley to one of those. Check out what Marlin009 did with his version (http://www.trainhornforums.com/showthread.php?t=6092)
Anyhoo… welcome to the forum and I look forward to seeing another horn install soon. Plenty of friendly help available here, but try not to double-post 
going over some installs im planing on just going thru a a line that u use a manual release seems simple and beter and this weekend im going to a flea market to see what I can get my hands on with a tank and a compressor that would work in my truck than just a house hold type . My bronco in the vab has so much room to install a line from the back to the under part of the body then a valve would be perfect on the center console and ill fersure have pics for a build (sorry bout tge douple post realised id get beter chances on the build thread ) :b
Manual valve on a budget, I use a 15mm compression fit plumbing lever valve, works perfect. a bit of 15mm copper pipe into each side of the valve and the 1/2" airline slips over the 15mm copper pipe, then with a generous helping of super glue & 2 x jubilee clips, Job done 
http://www.youtube.com/watch?v=0Malslmdxus
p.s I dont know if you guys use 15mm copper over there?
Welcome.
I was thinking like stinkypete - a ball valve would do the trick.
Getting one with 1/2" NPT threads would make your fittings easy.
I’ll just delete your other thread…
Welcome to the forum!
Welcome to the thread. Before I got my set of horns from Hornblasters, I built a set of PVC horns which I loved. The following link is to some suggestions I offered to another horn lover that was going to attempt to build a set of PVC horns. If you have any questions, feel free to PM me and I’ll do my best to help. I also agree with ear2ear that a cheap ball valve worked great. Thats what I used on mine. Good luck.
http://www.trainhornforums.com/showpost.php?p=64251&postcount=8