I asked a few days ago about horn relays and found out there was
none.  The reason for asking is that I wanted a bit more oomph from
an audio warning device and decided on air horns.

Now, the Wolo cheapie set I got said to use a 30A primary circuit and
a relay to set it off.  Whoa!  30A!  Well, I tried a few alligator
clip tests and sure enough, it burns out a 10A fuse, but 20A seems to
work.

After wrestling with how to do the wiring, I decided to keep it
separate from the horn circuit and installed a button on the steering
column.  Not as intuitive, but still not bad.  I ran a separate fused
line directly from the battery and through the firewall to the
compressor.  The compressor and horns are mounted on the frame near
the "meep-meep" horn.  I bled the button circuit power off the
cigarette lighter and mounted the relay to the right of the steering
column.

The sound is pretty impressive and unlike some stories I heard of lag
in air horns, this one comes on just about right away.  I've already
managed to scare some geese and my wife said the cat went through the
ceiling when I was testing (even though the door to the house was
closed).

Maybe not as elegant a solution as Michael Sullivan with his six horn
array, but still LOUD.  >:->

-Karl

Karl and Kristina Bloss, Trexlertown, PA
'87 GL Weekender  "Beverley"
Busses by the Trail: http://www.enter.net/~bloss/vw/bbtt