Home made foghorn
I build a lot of special effects for halloween and other events, I wanted some sound effects to use outdoors. I have seen hand operated foghorns (photo below) but they are not cheap to buy. I decided that I would build my own.
I looked at as many pictures of these foghorns as I could find on the web and realised that there were a few items knocking around in the workshop that could be adapted to make this happen!
The main ingredients, a double acting pump to drive it, a modified bottle trap for the diaphragm housing and a rubber glove for the diaphragm itself.
I started with the bottle trap, take off the trap cover and you will find a tube extending down, this needs to be cut off just above the level of the o-ring seal.
I also cut down the length of the cover to save space, drill a small hole in it to allow air to move when the diaphragm is moving.
The rubber glove needs to be cut to make the diaphragm, cut it to the outside diameter of trap seal o-ring, to assemble remove o-ring and replace it over the diaphrgm, trapping it in place. screwing the cover on will hold it firmly.
!
This can now be tested by blowing into the side hole on the bottle trap. To attach it to the pump an adaptor is required. Cut a short section of the screw on hose that comes with the pump and stick it into a plastic adaptor as below.
This adaptor can unscrewed if you need to use the pump for its original purpose.
