ee5391aa@hydra.unm.edu (Duke McMullan n5gax) (07/19/90)
In article <1990Jul16.220245.6545@mtcchi.uucp> cas@mtcchi.uucp (2668-Charles A Sherwood(Z550900)0000) writes: >My brother is interested in a fog horn for his boat. >Does anyone have a circuit that produces a fog horn like sound?? >How about an idea as what frequencies a fog horn puts out? Chuck, the frequency characteristic of the sound isn't the big thing: power is. IMHO, if you want a REAL loud sound, get a gas- or air-powered horn. Which you want depends on your bank account and "environmental consciousness". Unless I've missed a bet somewhere, an electronic foghorn of equivalent power to an acoustical horn is gonna cost huge bucks. Not ten feet from me is a little freon-driven hand-held horn I picked up for a few bucks at Wal-mart. It'll pin your ears together. It has some drawbacks, too -- get water in it, and it's likely to freeze up when you use it from the heat soaked up by the vaporizing freon. (I discovered this while blatting it underwater on Glendo Reservoir in Wyoming. Hey, I had to have SOMETHING to do while sitting in that dumb raft!) You can get electrically-driven (12v) compressor/reservoir/airhorn combos that may be what you want. They're electrically activated, too. A friend put one in his little Nipponese car about ten years back. Scared the feces out of me.... I don't recall the supplier...J.C. Whitney it may have been. BEEEEEEEP!, d -- "Peace is hell." -- Skyler Duke McMullan n5gax nss13429r phon505-255-4642 ee5391aa@hydra.unm.edu
ken@argus.UUCP (Kenneth Ng) (07/21/90)
In article <1990Jul18.172626.29473@ariel.unm.edu>, ee5391aa@hydra.unm.edu (Duke McMullan n5gax) writes:
: You can get electrically-driven (12v) compressor/reservoir/airhorn combos
: that may be what you want. They're electrically activated, too. A friend put
: one in his little Nipponese car about ten years back. Scared the feces out
: of me.... I don't recall the supplier...J.C. Whitney it may have been.
HeeHeeHee. My father has this interesting habit of "enhancing" the
characteristics of everything he is around. When we got the first
non American pickup truck (Toyota) he was, um, mildly displeased with
the <beep> toy horn. Rumaging around the basement he found the air horn
that was required by the Coast Guard (or some such agency) back when we
had the boat. So a couple weekends later he had a real horn, switchable
with a switch on the dash. Well, the next day, my mother had to take the
car to inspection, and didn't know about this switch. Part of inspection
was to toot the horn. According to her, the sound reverberated in the
hanger style garage and everyone turned around wondering what the hell
that was. She was furious that night, but my dad and I couldn't stop
giggling :-).europa@cbnewsh.att.com (r.j.capik) (07/24/90)
From article <1990Jul18.172626.29473@ariel.unm.edu>, by ee5391aa@hydra.unm.edu (Duke McMullan n5gax): > In article <1990Jul16.220245.6545@mtcchi.uucp> cas@mtcchi.uucp > (2668-Charles A Sherwood(Z550900)0000) writes: >>My brother is interested in a fog horn for his boat. >>Does anyone have a circuit that produces a fog horn like sound?? >>How about an idea as what frequencies a fog horn puts out? > > Chuck, the frequency characteristic of the sound isn't the big thing: power is. This is not correct. The sound power level and frequency range are fixed by both National and International regulations (typically 72 COLREGS), and depend on vessel size. In international waters for vessels less than 75 meters in length the fundamental frequency should be in the 250-700 Hz range. Minimum sound power levels also differ by vessel size. For vessels less than 20 meters in length the sound pressure level at one meter should be no less than 120 db (0.5 nautical mile range), and for vessels more than 20 and less than 70 meters the spl should be no less than 130 db at 1 meter (1 nautical mile range). The specifics are slightly different for inland waters. Sound signals in restricted visibility (ie: fog), should be sounded as one prolonged blast at intervals of not more than two minutes. > > > Unless I've missed a bet somewhere, an electronic foghorn of equivalent power > to an acoustical horn is gonna cost huge bucks. > OK, I'll buy that. However, small vessels only need a 0.5 nautical mile audibility range (90% probability of being heard on axis, in still air, with a ~63 db background level). I think you can get that range with a typical boom-box. Ron Capik homxa!lotus@ATT.COM