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.
Update: 7/2/2024
Special thanks to OSFA for making this possible!
Website: oldschoolfirealarms.com
YouTube: www.youtube.com/@OldSchoolFireAlarms
I bought a Simplex 4045-12 from Old School Fire Alarms!
This chime plays the E note.
Click here to listen to it ring.
According to OSFA, this particular chime was decommissioned from Kent State University, in Kent, Ohio, in April 2023. Unfortunately, the exact building it came out of is unknown. However, the building also had a Simplex 4203-4 FACP, dated 1967.
The chime must have been connected to a clock system, as it is attached to a Simplex 4033-13, with a semi-flush plate. I’m thinking that’s what allowed the chimes to go off when the clocks reached a certain time.
The self-regulating mechanism in the 4033-13 was made by IBM, patented in 1956. (2,754,495)
Click here to see the official PDF of the patent.
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Update: 11/3/2024
Sorry for the late update! Here are some new devices and parts in my collection.
Autocall Executive chime (from OSFA!)
Simplex 624-458 Single Projector (NIB) (Wishlist Item!)
The Autocall Executive chime plays the A note.
I’m not sure what ACDCSER means… Glenn told me that it ran on a 115 VAC control panel when it was previously installed. All of the bells and chimes on said system were 2.5 amps, which I think this chime is.
I recently discovered that MSU Mankato also had Autocall Executive chimes, though they were the later Federal Signal versions. I took this photo when I first visited campus. I think it was in one of the Highland buildings…
Special thanks to Old School Fire Alarms for selling me this chime! You’re the best!
I also found a red Simplex Type PR-1 single projector, NIB.
Apparently, the box was for a beige single projector, which is even more rare.
Part numbers:
624-458 - Red
624-457 - Beige
These are rebrands of Faraday’s 5001 single projector. I have one of these in beige, further back in my posts. Apparently, this one was repainted by Simplex. It’s the same high-quality red finish they use on their other products.
On my 4051
Here are some bonus photos of my collection!
The School Salvage Collection
Last December, I salvaged a handful of bells, and a few one-off devices from a 1950s school in my area, before it was sadly demolished earlier this year. I’d like to share the whole story sometime, but this will do for now.
1954 Building (IBM)
IBM 4015-4 RVF
IBM 4015-6 RVF
(all voltages unknown, as they were painted over)
Since the other bells were 120VAC, I’d like to assume these are, too, but I’m not sure…
IBM RVG 10" Bell (unknown model and voltage)
This bell is sadly in parts, right now, as it had to be taken apart in order to remove it from the building. It was an exterior bell, and was painted over a few times.
As you can see, the striker is also in pieces. It fell out as my dad was removing it. I’d like to fix it and restore it someday.
1971 Addition (Simplex)
Simplex 4017-42 4" Bells
Simplex 4017-62 6" Bell
Simplex RVG4018-3A 8" Weatherproof Bell
Edwards 241 Heat Detector on a unique plate
Edwards 870/871 flush-mounted horn (unknown voltage)
The back of this Edwards horn is very rusty… I wish I took another one of the plates in the building that weren’t. This was the only one of its kind in the building.
This bell was in the swimming pool area of the 1971 addition, resulting in the corroded finish.
One-Off Devices
American Time & Signal 1005 4" Bell (120VAC, W.L. Jenkins rebrand)
Silent Knight PS-SATK Pull Station
ESL 711U Photoelectric 2-Wire Smoke Head (semi-NIB)
Chemetronics 603 Heat Detector w/base
System Sensor I3 Smoke Detector Head Box (no detector)
Wheelock AS Horn Strobe (destroyed by scrappers)
I wasn’t able to find any I3 heads in the building, sadly… I re-used the leftover box to store the Chemetronics heat detector.
My first official smoke detector head! It even came somewhat NIB, with a dust cover.
Sadly, when I was there to salvage what I could, the scrappers already got the fire alarm system… (hence the missing I3) I found this shell of one of the Wheelock AS’s that were there. All that’s left is a speaker, and a broken base. RIP
I found this unused pull station on top of the Silent Knight 5207 in the janitor’s closet. (also scrapped when I got there
) The key is actually from that panel.
I donated two of the bells to the town’s museum. They also have the building’s original blueprints in their archives.
Here’s a sneak peek of what the school looked like. I’ll share more when I post my story. This was a very interesting and beautiful building, and I’m still sad it’s now gone…
(You can see one of the 4017 bells that I now have in my collection in this photo!)
Click HERE for the story about this school.
did that chime come out of a hospital somewhere in his territory? I know another collector from Ann Arbor that has one of those in black, he goes by Mr4246-2 on YouTube. I personally wish I let him know about the demolition of a historic hospital in Akron (St. Thomas, where Alcoholics Anonymous was formed) it may have had something cool
also do the semi-flush IBM bells have their original backboxes?
I’m not sure where the chime came from… Just looked up St. Thomas. What a beautiful building it was. Maybe my Executive chime came from there? I’ll have to ask Glenn about that. Update: 11/5/2024 - The Autocall Executive chime in my collection came from Stockdale Hall, at Kent State University. (c. 1948) Stockdale Safety Building · Kent State University Libraries. Special Collections and Archives
I’m familiar with his video. That’s cool that he was able to get a chime from his school! Pretty neat collection, too.
No, I don’t have the backboxes for them, unfortunately… They were stuck pretty good, and even if I did have the tools to get them out, I didn’t want to risk lyme or asbestos exposure breaking the walls.
The box on the right is where the 6" bell was mounted. This was in the cafetorium. The bells were screwed directly to the wall. I’m not familiar with IBM’s bells, so whether these were the original backboxes or not, I don’t know… If they were, RIP.
I wonder if you thought of using a chisel or an orbital saw for those kinds of backboxes.
My mother might be familiar with that building at Kent State; she was a student there in the mid 80s. One of my favorite buildings is Engelman Hall, which has a really cool sign
also, I plan to move to Pittsburgh since Akron keeps demolishing all of its historic buildings, really is a waste of my tax dollars, I personally wish they turned it into apartments instead of imploding it