Easy PVC Fog Horn




About: I like turning boring things into awesome things! Usually on video.

How to make a simple Air Horn. These horns are LOUD! They can be scaled up as I show in the video and made even larger still, but be aware that the bigger you make them the more air they will take to function.

I went through quite a few ideas before coming up with the final design. The only tools required are a hand saw and scissors. Isn't it great when a project is that simple?

Parts (small version):

  • 1"x 1"x 1/2" T Fitting
  • 1" x 1/2" Adapter
  • 1" Plug
  • 6" x 1/2" PVC Pipe
  • Freezer Bag
  • Long Funnel (found at auto parts stores)

Parts (larger version):

  • 2"x 2"x 2" T Fitting
  • 2"x 1" Adapter
  • 2" Plug
  • 6" x 1" PVC Pipe
  • 1" Coupling
  • Large Funnel
  • Freezer Bag
  • 2"x 1" Reducer
  • 1"x 1/2" Reducer

Both horns are operated using a large manual air pump in the video, though they can also function using compressed air or simply by blowing into the inlet with lung power.

If high pressure air is used it might be necessary to find a more durable diaphragm. Any sort of rubber or film should function nicely, and can be stretched over the end of the T and held in place with a hose clamp rather than being pressed in with a plug.



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8 Discussions


3 years ago on Introduction

i made one and my only problem is inconsistency in the sound. I seem to ned to continuously adjust the closeness of the long sound pipe to the diaphragm to get a decent sound. Sometimes it's practically a squeal, others it's a nice deep foghorn, then sometimes no toot at sll.. Any ideas for me? Thanks.

2 replies

You might do better to use a heavier duty diaphragm that won't stretch and deform. You can take the plug out that holds the plastic bag in and instead use a hose clamp to hold a piece of rubber right over the end of the T. That should be more durable.

The diaphragm is a heavy duty piece of flexible rubber, normally used by phsical therapists to provide stretchy resistance for strength building by standing on the center of the about four foot long segment and pulling the ends up with the arms. Maybe it us too stretchy. I'll try a piece of tougher rubber glove and a hose coamp. Thanks for the quick response. I live on a Puget Sound beach and am looking forward to treating my neighbors to a good deep foghorn sound on a foggy day. We get about a dozen a year here.

Ronald Bragg

4 years ago

Did not show me how to make it .Sure do like it


I like the project, I'm not sure I like the unrelated segued referral to and upselling opportunity of the alleged video sponsor though, but yeah, it does look fun and easy.