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Discussion Starter · #1 ·
There is nothing quite so “alarming” as a loud horn blasting when you least expect it. This year I decided to make two of these horn scares for the Haunted Forest. They both work on basically the same principle with just a slight difference in the triggering mechanism. One works on a pressure switch trigger and the other works with a pressure release switch as the trigger. Since they both are made with basically the same wiring configuration I am only showing the build for the seat box scare in this tutorial.

I should mention now that after I built these two props a few weeks ago I did notice that another member had posted a tutorial titled “Horn and Light Scare DYI” by Mike and Tiff. Their prop is a really great build and I like it a lot. The design of my build is very similar to Mike and TIff's except rather than being a “passive” scare where people only have to walk by the prop to trigger it this design does not require anyone to push a button or rely on a motion sensor or any other external controller to trigger. The design of this prop is an “interactive” scare where the poor unsuspecting souls in the Haunted Forest unwittingly actually SCARE THEMSELVES!!! Muwahahaha.

Here is what you need:

A box to put the device in. I found these at a thrift store for $4.00 each. The box on the left I made into my Treat Box Scare and the one on the right is my Seat Box Scare.

Furniture Box Wood Chest Wood stain

A horn or any other loud sound device. The AhOooGaa horn was $9.95 at Harbor Freight and the Air Horn was $14.95 also at Harbor Freight

Product Red Cylinder Plumbing fitting Plastic
Plastic Wheel

A Pipe Rail Tie to mount the horn - $3.19 at Lowes

Aluminium Metal

An “ON-OFF” switch - $2.95 at Wal-Mart

Product Electronic device Tool accessory Switch

A 12v battery with enough amps to power the horn - $19.95 at Wal-Mart (Lawn Mower Battery)

Automotive battery Product Auto part Technology Electronic device

Some light gauge stranded wire and wire connectors
Short pieces of light chain
Depending on how you want to trigger the horn you will need either:
A SPDT Micro switch for pressure release activation or a momentary switch for pressure activation. Each was $3.95 at Radio Shack.

Technology Switch Electronic device Electronic component Circuit component
Circuit component Technology Electronic component Electronic device Electronics

2- springs - $4.49 at Lowes
2- short pieces of ½” PVC pipe
4 - ½” PVC pipe hangers

Drill and drill bits
Wire crimpers
Some screws
Screw driver or screw driver bit for the drill
Maybe a hot glue gun and glue sticks

OK, Now we’re ready! Since the basic wiring circuit is the same for both props I am only showing wiring photos of the seat prop. The only difference is the type of trigger used in each box.

First decide on the design of your scare and determine where each component will be placed in the box. Now place each component where you want it in the box. This seat box scare will be operated by a pressure switch using the AhOooGaa horn and the treat box prop will be triggered using the pressure release switch using the air horn. I added the larger feet to the seat box prop to make it more stable.

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Now drill a hole in the back of your box to install the ‘ON-OFF” switch. You want this switch so you will be able to turn the device off in the event someone manages to set the thing off and it won’t quit alarming. Install the switch and drill another small hole near this switch to run wires from inside the box to the switch terminals.

Wood Wood stain Plywood Hardwood Table

Now run a wire from the positive side of the battery to one terminal of the “ON-OFF” switch.

Wire Electrical wiring Electronics Cable Electrical network

Then run a wire from the other side of the “ON-OFF” switch to one terminal of your trigger switch.

Wire Electrical wiring Electronics Electrical network Technology

Now run a wire from the other terminal of your trigger switch to the positive terminal of your horn.

Wire Electrical wiring Electronics Electrical network Technology
Floor Tool accessory Machine Flooring

Last run a wire from the negative terminal of the horn back to the negative side of the battery.

Wire Electrical wiring Electronics Electrical network Cable

For this seat box prop I put the AhOooGaa horn under the box since the lid will be closed on the box when it triggers this horn. If I put the AhOoooGaa horn inside the box the sound would be muffled quite a bit by the lid closing on the box and enclosing the horn inside.

Since invariably there will be people who cannot resist messing with props you will also want some way to keep nosey people from opening your box but still allow the lid of the box to move to trigger the horn. I solved this problem by attaching a very short piece of chain from the box lid to the side of the box.

Wood Wood stain Hardwood Plywood Table

Now that everything is ready all you need to do is adjust the triggers to allow the switches to work. On the pressure switch scare the horn will sound when pressure is put on the momentary switch and the electrical circuit is completed but when the pressure is released the circuit is broken and the horn will stop sounding. For this adjustment I used two springs from Lowes placed in ½” PVC pipe to hold the lid off the pressure switch. Now when the lid is depressed (in this case someone sits on the small bench) the horn will sound but when they jump up (and of course they will) the horn will stop.

On the pressure release switch scare I used a screw attached to the underside of the lid to hold the switch down until the box lid is lifted slightly. When the switch is depressed by the lid the circuit is open and no current flows to the horn. When the switch is released by someone attempting to open the box the circuit is completed and the horn sounds. When they jump back and release the lid it depresses the switch which opens the circuit and shuts down the horn.

Here is a photo of the two types of switches. The fist photo is the pressure switch. You can also see one of the adjustment springs in this photo. The second photo shows the pressure release switch.

Wire Technology Wood Hardwood Electrical wiring
Wire Electrical wiring Cable Electrical connector Electronics accessory

You will probably find that you will need to take a little time to make adjustments for the triggers to work properly.
If desired you can also add any other 12v device to trigger at the same time as the horn such as a light like the one made by Mike and Tiff. All you have to do is wire it into the circuit along with the horn.

Once you get everything together it really only takes about 45 minutes to put it together. These props are quick, easy, not overly expensive and it scared Wicket Grandma right out from under her pointy hat when she foolishly ventured into the shop to see what I was doing.

You can see both of these props in operation here: https://youtu.be/h7BOhoIHv9E

1,367 Posts
Fantastic thread! I would post a sign or paint on the items something like "do not open" or "do not sit". It will give the offenders quite a surprise. I will certainly be stealing this for next year. I can see making a throne chair with a sign saying "reserved for the chosen one" and if someone sits on it then the horn goes off.

Great job.

1,367 Posts
Damn you SP. I am in for this year. I pulled the trigger on a large 4 inch LED lit red push button. Even with my expert level of procrastination, I should be able to knock out this project before Halloween. I plan to make sign that says "Do Not Push" and have an air horn activate when pushed. It will almost be a behavioral experiment in addition to a startle scare. :D

I will attach my build to your thread if you don't mind, so people can see my variation. Below is the LED lit red button that I purchased.


572 Posts
Discussion Starter · #5 ·
Thanks DaveintheGrave, The toilet paper might not be a bad idea at that! :D

Col. Fryght, LOL...Can't wait to see your build. Of course I am happy for you to add it to this thread.

I have the Spirit Halloween Electrocution panel prop that I added a couple of "Danger" and "Do Not Flip This Switch" signs to as you suggested for these props. I actually have it wired up to the Death Row Inmate guy from Spirit Halloween as well but rather than having him in an electrocution chair I have him set up as an electrician working on the "Haunted Forest Power Plant" prop that I made. He is sitting on his tool box next to the power generator holding a couple of bare electric wires in his hands. Of course as you suspect everyone automatically flipped that switch. They just can't resist doing something they are told not to do, and when they do flip the switch the electrician gets the shock of his life as well as the guest getting a scare from the electric panel springing open. The combination of the two props working together was a big hit for our Haunted Forest guests last Halloween.

For these horn scare props I am going to just let them be sitting around innocently minding their own business. No warning signs or anything like that. I think that way no one will be actually expecting anything to happen. The treat box prop will be on Wicked Grandma's food table with maybe some candy or other treats around it to give the idea there is something good inside and the seat box prop will be either in the campground around the bonfire or along one of the trails in the Haunted Forest. I might add my small, table top, sound activated jumping spider next to the treat box prop for an additional scare when the spider activates at the sound of the horn. At about 135 decibels each these props should produce some exciting results when some unsuspecting victim operates them. The horns are actually much louder than it appears in the video.

By the way...I finally got around to posting the video of my horn scare working on youtube so the link is now in my original post above.
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