I’ve never seen this old Federal Signal logo before! Very cool!
I’m wondering how these old mechanical horn/strobes generate high voltage power for the flashbulbs inside… Back in the age when these horns were widely used, it’s kinda unlikely that there were any solid state voltage boosters that’re tiny enough to be placed inside’em.
Is the high voltage generated from another set of windings on the horn solenoid?
Sorry for the late reply.
I’m not an expert on this, but here’s what I know from some research.
On older devices, such as the Wheelock 7002-24, the strobe is connected in a series circuit, starting from the positive (red) lead, to the electromagnet, then to the horn solenoid, and to the strobe circuit itself. The strobe then connects to the main negative (black) lead, and either goes to another DC horn, or the source itself.
This diagram shows how it works.
(I know it’s not a proper electrical diagram, but this is how I’m able to visualize it.)
In a series circuit, every device (e.g. the horn mechanism and strobe) is hooked up to one-another with one path of current flow (through the pigtail wires). This applies to most fire alarm systems and NA’s themselves from this era, afaik. That’s why some devices can’t be tested strobe-only, as the strobe provides the only path back to the source. You’d have to disconnect the strobe from the horn to test it independently.
The 7002-24 was first produced in the mid-late 1970s. Back then, horn-strobes weren’t even a thing yet. Horns with light plates were available, such as the well-known Simplex 4050-80 series, but Wheelock was the first company to offer horn-strobes. (I found this out from Vintage Vibratone.)
The strobe is powered by a capacitor in the plastic strobe housing itself. Wheelock had to compromise between the flashtube’s required voltage to flash bright enough, and the horn mechanism itself, when they chose the capacitor. As it needs a certain voltage for the tube to flash, it takes power away from the horn until it fully charges up. When the strobe flashes, it stops charging for a split second, causing extra power to go to the horn instead. This is what causes that iconic “skipping noise.”
Newer devices from the 80s and early 90s, such as the simplex 2903/4903 series horn-strobes, almost-never have this problem. Over time, strobes evolved to be smaller, flash brighter, and require less voltage. Thus, the horns don’t skip, unless it’s starting to die out, like this Simplex 4903-9217, featured in this video by Fahrenheit4051.
Fire Alarm Signals - Edwards & Simplex (Fahrenheit4051)
I would’ve checked the voltage of the strobes themselves, but I didn’t want to risk damaging my devices… But I think that’s how they work. I hope this answers your question. 
Experts, feel free to correct me.
Thanks for your explanation. Now I’ve got some idea.
I got these new devices long ago, but I haven’t been able to post them until today.
First off:
My Simplex 4050 (left) and Simplex 4051 (right)
Simplex 4050 (old label, from a demolition site in Champaign, IL)
Simplex 4051 (newer label, from VibratoneKing)
Both horns, with 624-449 flush grilles. My 4050 came with the original plate. I bought one for my 4051.
Now all I need is a single-zone 4208 panel… lol
Faraday 5002 double-projector (beige) with original box. R.I.P. box…
I now have the beige variants of both projectors! Now I just need to find some beige flush mount plates…
My 5410 with the 5002
The last devices I could take pictures of:
My two FCI MS-2s.
These pull stations were taken out of service because they wouldn’t stay pulled.
My high school has those exact 4050s, except they’re 6 volts. You might know what high school I go to. Those are rare devices you have!! Whenever I find stuff like that, it’s way out of my budget!!
Yep, I watched your video. Pretty cool to see they still have those double projectors on them.
I know your pain. The beige 5002 double projector set me back $100. Ironically, the same seller was selling NIB horns for $50. Still happy with my purchase, though. Collecting vintage fire alarms can be an expensive hobby. lol
Nice finds!
Yeah!! I may be getting two 4050s!! OSFA will be getting this rare FA system once it gets replaced in the near future!! The newer buildings in my district have automated voice FA systems. One of them has been painted over several times; I will be sending that to Liftinmike for destruction. I think the replacement FA system may be the same type!
Those are some really nice vintage alarms, I especially like that break glass t-bar from the 70.s and those Hutson keys are cool too
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BIG Update. Here we go…
Simplex 4048 R (6VAC)
Simplex 4050 (6VAC) (Spartex variant)
This particular 4050 has spartex coating, which dates this horn back to the late 70s/early 80s.
The label has larger text, but still has the classic Simplex “globe” logo.
80s ← Mid 70s ← Late 60s
It also came with a spartex 2905-9907 double projector, which I’ve been looking for for a long time.
Faraday 5970 (Beige 120VAC ver. of 9833)
Simplex 4251-111 and 4299-3 backbox
This pull station probably came from the same system as my older 4050. Previous owners re-painted parts of the box.
Gamewell/FCI MS-95T (Man. 2001)
This is a common pull station I saw at my local university. Since I won’t be able to get devices from there (all property is state-owned and would have to be auctioned), I got lucky and found this one instead.
~Plates Galore!~
Simplex 2905-9909 Concealed Circuit plate (NIB)
Simplex 2905-9903 Semi-Flush plate (NIB, 80s spartex version)
Simplex 2905-9904 Semi-Flush plate (Rare beige variant)
Simplex 2905-9902 Flush Grille plate (Rare beige variant)
I think I have an unhealthy obsession with mounting apparatus… lol
And last, but not least…
Simplex 4025-13 (3VAC)
I’ve seen other variants and rebrands of this particular chime before, but not a Simplex version… If anyone has any information about these chimes, please spill the beans. I’m rather curious.
I like that ms-95t and those plates
Update: 11/6/2023
Uffdah! It’s been almost a year since I’ve updated my collection list. I’ve gotten a few new devices and parts since then that I would like to show you.
Group Photo
Simplex 4060-8 Bell Mechanism w/ Chime Kit (1.2VDC)
Simplex 4050 (Red, smooth finish, 6VAC)
Simplex 2905-9907 (Red, smooth finish)
Simplex 2904-9005 remote light (24VAC)
Simplex 4040 (Red, smooth finish, 12VAC)
Simplex 4090-2 w/ 4" Gong (Beige, smooth finish, 120VAC)
Simplex 2905-9903 (white spartex, NIB)
Simplex 2905-9901 (red spartex, NIB)
Edwards 364 Adaptahorn (20VAC)
Faraday 10123-1 pull station w/key
Federal Signal PR* Single Projector (FS metallic finish, NIB)
IBM 4047-1A Chime (IBM silver finish) (most-recent addition)
I was finally able to find some items on my wishlist, and those are:
Simplex 2905-9907 Red, Smooth Finish Double Projector (which came with a 6VAC Simplex 4050)
And… an IBM 4047-1A Chime
I never knew IBM made the 4047-1A. Apparently, these date back to Autocall, as they were called “Xylotones.” Since these chimes sell fast, I just had to get it before it disappeared into the hands of a secretive collector.
CLICK HERE to watch a video of me ringing it. (Google Drive)
No recordings or videos of these chimes have ever surfaced, so I’m proud to possibly be the first one to make one.
The chime plays the B note, same as my Simplex 4025-13.
I unfortunately don’t know how to power this chime, as it doesn’t say what voltage it takes on the tag. It only says 2.5 Amps, AC-DC in the voltage section, and SER (probably series) in the cycles section.