hey fire alarm fans! we all know those mechanical fire alarms right? the 2901 9800 series horns or the old wheelock alarms (the DC ones) the reason im posting this is because i want to make one. any ideas how? requirements: runs on DC, all parts on back ACCEPT daifram, buzzes, and is LLLOOOUUUDDD. tell me if you have any ideas.
thanks, S 9833
A good place to start would be building a simple buzzer based on projects you can find online and then building upon your knowledge gained from the project in order to build a more complex horn. Once you reach that point, or if you already understand the mechanics of the device, start by making a plan of how the parts will fit together, how the magnet and components will be mounted, etc. A 4" conduit box extender ring would make a good frame for the horn, and then you could cut a piece of flexible metal to size and mount it to the “back”, where the extender ring would normally connect to the main conduit box, using the existing mounting holes and some screws and nuts, for use as the diagram. Mount a 2 gang adapter ring over this, to keep the plate in place and allow it to vibrate correctly. Then you could use a blank plate, which would attach to the “front” of the box, to mount the electromagnet and switching mechanism. Finally, using the two gang adapter plate added earlier, you could mount a grille or cover over the diaphragm, or in the future, even a light or strobe assembly. If you want I could make a diagram of how I envision this going together, or maybe even a picture because I now feel motivated to build one :lol:
I don’t know if someone who can barely form a sentence will be able to build a fire alarm horn. 
Are you including a diaphragm or not? You will need one to make any buzzer work.
i will be including the diaphragm.
as for the solenoin couls a sprinkler valve solenoid work?
The solenoid you use has to be strong enough to move the diaphragm, if even only a small bit. So if it is strong and you can find a way to mount it inside the horn, it should work.
I’d recommend basing your design off the Type 2 Electromechanical Horn design.
Below are some animated GIFs I made a while back showing different methods of making electromechanical horns.
Type 1 Horn:
Examples: Federal Vibratone 350, Faraday 5720, 5740, Simplex 4030, 4040, 4050, Edwards AdaptaHorns
Type 2 Horn:
Examples: Federal Vibratone 450 (Series A & B), Simplex 4041, 2901-9806, Wheelock 31, 34, 31T, 34T, 7001, 7002, 7001T, 7002T, 7004, 7004T, Amseco BZ-series
Type 2 Horn (Faraday version):
Examples: Federal Vibratone 450 (Series C), Simplex 2901-9833, 2901-9838, 2901-9840, 2901-9845, 2901-9846, Faraday 4120, 5920, 5940, 6020, 6040, 6120, 6140
Type 3 Horn:
Examples: Federal Vibratone 450 (Series D), Simplex 4901, 4903 series, Faraday 6230 – 6258, Siemens / Cerberus Pyrotronics U-HN, U-NH, U-HNH, Gentex GMS / GMH
Just a question, which one would the Edwards 895 use?
A slightly different version of the Type 1, same thing for all Adaptahorns.
Okay, thanks! 
Weren’t those on the DFA site?
my sprinkler valve solenoid should work i will be using the type 2 design
thx!
someone just gave me a few more solenoids imma be daring and thy to make a type 3 horn. i got the type 2 horn done and it works great. and i was surprised by the sound output-- 117.3 db
Can you make a short video? I’d LOVE to see this.
You must be very skeptical…
No, I’m just curious how it came out and how it sounds!
sorry i cant as my camera died a couple weeks ago. but i will somehow try to get a vid of an alarm that sounds like it.
I would say really low pitch