The Stovebolt Site Forums The Parking Lot Big Bolts Wanting an Air Horn?

I have a small assortment of air horns that I have picked over the years and decided one should go on my '51 4400. For the Memorial Day parade here in town, I used cable ties and attached one to the mirror bracket and rigged up a scuba tank using a compressed air blow off gizmo for the valve and filled it to 120psi with my shop compressor. Unfortunately the blow off gizmo leaked both at the button trigger and out its nozzle so my night before preparations did me no good as the tank was empty in the morning. I have since bought a true air horn valve but wonder if there are 6v air compressors out there. I would still use the scuba tank has a reservoir but would like the system to be self sustaining rather than having to fill the tank before going on the road. I will be mounting the horns to the cab roof soon. Thanks for any guidance on this!