Instructables
Picture of Loud foghorn from plumbing parts
old one01.jpg
This is a how to for building a loud foghorn from easy to get plumbing fittings and an inexpensive double acting air pump, the idea was to emulate the hand operated type used on small ships until the 1950's shown in pic 2.
 
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Step 1: What you need

Picture of what you need
Here are the basic parts to make a noise

A hand operated pump, a sink waste trap and a rubber glove (for the diaphragm)

Step 2: Preparing parts

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The trap needs the down tube cutting off 1mm above the level of the outer edge, this cut needs to be accurate as this is where the diapragm will go so make sure you smoothe the cut edge with emery cloth.
 I cut the bowl down to size by cutting a section out and sticking the 2 end parts back together. drill a small hole in the back of this part so that it isn't fully sealed.

Step 3: The noise maker

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Cut a circle of rubber from the glove that is just bigger than the size of the o'ring that seals the bowl, lay it on to the o'ring joint  face and trap it with the o'ring before winding on the bowl.

At this stage if you blow into the side of the fitting you will make a noise :)

Step 4: Attaching to the pump

Picture of Attaching to the pump
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I am fortunate as I have a lathe and turned up the adaptor from a piece of plastic, but an adaptor can be made from standard plumbing plastic fittings glued together, the main thing to remember is to have a short length of the connection tube that comes with ther pump glued into one end to allow the adaptor to be screwed on and off (allowing the pump to be used for its original purpose).

Step 5: It should now work

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With the parts assembled you now have a working horn and could leave it right there......

Step 6: Making it lower and louder

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This where you can go mad!  Get as many plumbing parts as you can screw and glue together to make the sound path long and wider.
I added a second sink trap........
KevinOKane1 year ago
I have seen several items built out of recycled plumbing parts but this is something new to me. I did not know that you could actually build a sound instrument that actually works fine out of plumbing fittings. I am still unable to figure out how air from the pump can actually produce sound just by passing through the pipings. I guess I would have to build one up to experience it personally.
rog8811 (author)  KevinOKane12 months ago
The sound is made when the air from the pump forces its way past the rubber glove diaphragm the pipes just shape and amplify the sound.
Good luck with building your own.

Regards rog
Chief6661 year ago
Dear rog 8811,

I love your project and will start to build one soon. Just so I get my mind around what you are suggesting - the larger the diameter (of the horn section) the deeper the noise? If this is the case have you any comment on the max size that is achievable?

I was thinking of using an old fire extinguisher and cutting the bottom off.....

Thanks in advance
rog8811 (author)  Chief6661 year ago
Hi Chief, from experiments when building mine every time I lengthened the air path, by adding bits in, the pitch went lower.
The bigger the horn outlet the louder it became.

I hope that helps you with the design, good luck!

Regards rog8811
IvanGorski2 years ago
Hey Rog, Great project! I want to make one, but where can I find a bottle trap like the one you used?
rog8811 (author)  IvanGorski2 years ago
Hi, I am UK based and found the trap in either a B&Q or Wickes store, sorry I cannot give you any more than that.
Good luck with finding the correct part.
rog8811 (author) 2 years ago
You could use pvc solvent adhesive, the sort used when joining plastic pipes.
I think I used quick setting 2 part epoxy...5 minute araldite.
xnerdyxboyx2 years ago
How do you "stick" the 2 end parts back together?
Bubbler2 years ago
This horn could be used to accompany the barking dog from next door. Or better still, use it when the barking dog's owner is trying to get some sleep. I like this one, and with a bit of echo added to the sound, we could be out on the calm icy seas off of Newfoundland.
rog8811 (author)  Bubbler2 years ago
I mounted a motor in the end of the horn to rotate a baffle, a sort of leslie speaker cabinet type thing, it spun up a baffle to try for a reverb... I didn't have time to get it working as I was a day away from halloween and didn't have the time to play.....

I must try it again with a higher geared motor some time.

I am pleased that folk like this build.

Regards Rog8811
halzark3 years ago
Awesome Possum!
thejiggse3 years ago
Get some aluminum flashing, roll it into a cone shape, use aluminum hvac tape to retain the shape and then use the tape to secure it to the foghorn. By building four or five of these things with differing megaphone sizes your neighbors will quake with fear, as they think that they are hearing the aliens from War of the Worlds. How fun would it be to build about 20, and then set the neighborhood kids loose with them?

I think of Robert Duvall in Apocalypse Now, "I love the smell of napalm in the morning,..., it smells like victory!"

I say, "I love the sound of foghorns in the morning,...,it sounds like aliens have emerged from underground!"
tanniynim3 years ago
I'm not following where we need to "drill a small hole in the back of this part so that it isn't fully sealed." Can you clarify this with another diagram or more information?

Also, is it necessary to "cut the bowl down to size by cutting a section out and sticking the 2 end parts back together?" Does this effect the sound if you don't?
rog8811 (author)  tanniynim3 years ago
The hole is just a small one drilled somewhere in the screw on domed cover  to make sure that the volume behind the diapragm isn't sealed. The same part in fact that you asked about cutting.......
I do not know what difference not cutting this same part down in length will make, try it!
I shortened it as most fog horns have a very small volume of air space behind the diapragm.

Hope that helps.

Regards rog8811
I will try it before cutting! If we can save a step, lets do it!
ynze3 years ago
Vuvuzela-horror! GREAT PROJECT!!!

Y.
Kiteman3 years ago
You could add to the authenticity by adding a traffic cone.

Oh, and paint it.
rog8811 (author)  Kiteman3 years ago
I did look at a traffic cone when I was gathering parts, the trouble with them I found was that they are very heavy and actually damp the sound a bit due to the thick wall. I doubt I will paint it as I like the fact it looks like what it is, a load of plumbing fittings connected to a pump :)
Just use one of those small cheap ones. Those should do fine.
SHIFT!3 years ago
This is such a fantastic project! I love foghorns but I hate having to refill the compressed air canister- plus this is much more affordable and hand powered too!

This is going straight to my "Favorites"!
bwells23 years ago
Awesome!
Cabe3 years ago
Did we learn nothing from the scourge of the Vuvuzela ? :)
rimar20003 years ago
Some years ago (maybe 20) I did a passive megaphone using a wasted central rotor from a cloth-washing machine. It was very effective, because its almost perfect horn shape.
rog8811 (author)  rimar20003 years ago
I remember my old mum had one like that many years ago, if I had come across one of those I would have given it a go, it would look good too!
Thanks for your response. I found one of these "horns" a week ago in the waste, and brings it at home. Anyway, they are cheap even new, as replacement.

Maybe I will post soon an instructable about that passive megaphone.