Old Whelen Power Supplies

[JohnMarcson]

Starting in this thread we have been looking at older Whelen power supplies. Here are a few more.

This strobe II of dubious nature (opened up and markings written over), looks modified, but works. Note the small dial in one of the pics changes the flash rate. It was inside a 5000 series beacon but looked like it had been used as a replacement. The attached par36 strobes I used to test it were just known working tubes that I didn't mind if they were damaged (no attempt to be accurate).

 

[JohnMarcson]

Starting in this thread we have been looking at older Whelen power supplies. Here are a few more.

Strobe II of dubious nature, looks modified, but works. Note the small dial in one of the pics changes the flash rate.

View attachment 235995View attachment 235994

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A more intact 2 head version, perhaps a bit newer

 

[JohnMarcson]

Starting in this thread we have been looking at older Whelen power supplies. Here are a few more.

Strobe II of dubious nature, looks modified, but works. Note the small dial in one of the pics changes the flash rate.

View attachment 235995View attachment 235994

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A 4 head version UPS60 used in various applications, no speed control "knob"

 

[JohnMarcson]

Starting in this thread we have been looking at older Whelen power supplies. Here are a few more.

Strobe II of dubious nature, looks modified, but works. Note the small dial in one of the pics changes the flash rate.

View attachment 235995View attachment 235994

View attachment 235996

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A UPS65 supply with variable flash rate (note speed "knob"), used in various applications.

 

[RS485]

So, FWIW -- To me, Whelen's power supplies broke down in four eras:
1: https://patentimages.storage.googleapis.com/f9/29/5d/d07de18375a040/US3515973.pdf
2: https://patentimages.storage.googleapis.com/9e/6d/fd/00db4b9bd20e80/US4013921.pdf
3: https://patentimages.storage.googleapis.com/ac/b2/7a/c8827c6c360890/US4321507.pdf
4: https://patentimages.storage.googleapis.com/fe/72/1b/590040789fc131/US5013973.pdf
Whelen wasn't by any means the only party exploring the physics here, and anyone really interested in pure Xenon gas discharge technology, there are plenty of other great sources of info out there.
But W/R/T Whelen (which I personally dig) -- I found these patents "enlightening".

 

[JohnMarcson]

So, FWIW -- To me, Whelen's power supplies broke down in four eras:
1: https://patentimages.storage.googleapis.com/f9/29/5d/d07de18375a040/US3515973.pdf
2: https://patentimages.storage.googleapis.com/9e/6d/fd/00db4b9bd20e80/US4013921.pdf
3: https://patentimages.storage.googleapis.com/ac/b2/7a/c8827c6c360890/US4321507.pdf
4: https://patentimages.storage.googleapis.com/fe/72/1b/590040789fc131/US5013973.pdf
Whelen wasn't by any means the only party exploring the physics here, and anyone really interested in pure Xenon gas discharge technology, there are plenty of other great sources of info out there.
But W/R/T Whelen (which I personally dig) -- I found these patents "enlightening".

Very good info. Any idea what the specific relationship between Austin Electronics and Whelen started out as? Was Austin the strobe tech company and Whelen the overall lights? I was never clear on the exact relationship, especially in the beginning. Separate Austin products didn't fully appear as the amber line until the 80s then rejoined into overall Whelen line in the late 90s.

 

[RS485]

I wish I knew more about the Whelen/Austin relationship.

I too have strange 15.2 Volt 1200:


John, you might find the "speed knob" on the back of your UPS64. Here's mine:

The knob on the right side adjusts the point at which the inverter turns off either because of low-power, or missing/defective tube(s). The '507 patent describes this in good detail.

Also, it looks like the newer USP64 you have was an example of patent US5013973 applied where rather than using a clunky old-school power transistor, it used a FET instead which allowed the inverter to cycle much more quickly but ended the era of "singing" power supplies.

There's also an interesting difference between the older UPSs you first showed (these pics are from a couple very similar ones I have).


On the left is a single "AE1 219" integrated circuit. On the right, 3 "555" timer ICs and a common flip-flop

In both cases, these ICs drive the trigger circuit (flash timing and output selection)
I believe the "AE1 219" was a custom-made IC (hence the "AE") and that it was likely pricey. As IC prices fell, I'm guessing it became more attractive to use common (less expensive) ICs...but this is just my interpretation.

Sorry if this is boring but this stuff fascinates me!

 

[JohnMarcson]

I wish I knew more about the Whelen/Austin relationship.

I too have strange 15.2 Volt 1200:
View attachment 236048

John, you might find the "speed knob" on the back of your UPS64. Here's mine:
View attachment 236049
The knob on the right side adjusts the point at which the inverter turns off either because of low-power, or missing/defective tube(s). The '507 patent describes this in good detail.

Also, it looks like the newer USP64 you have was an example of patent US5013973 applied where rather than using a clunky old-school power transistor, it used a FET instead which allowed the inverter to cycle much more quickly but ended the era of "singing" power supplies.

There's also an interesting difference between the older UPSs you first showed (these pics are from a couple very similar ones I have).

View attachment 236050
On the left is a single "AE1 219" integrated circuit. On the right, 3 "555" timer ICs and a common flip-flop

In both cases, these ICs drive the trigger circuit (flash timing and output selection)
I believe the "AE1 219" was a custom-made IC (hence the "AE") and that it was likely pricey. As IC prices fell, I'm guessing it became more attractive to use common (less expensive) ICs...but this is just my interpretation.

Sorry if this is boring but this stuff fascinates me!

This is all really interesting to me. I had another older supply with "15.2" written in too. I'm not sure if it's the max voltage or why that would be noted like that. The part sourcing is also interesting because I have noticed similar differences in "the same model". I have some supplies in devices like the dash master II that have "speed" or cutoff "knobs" and then ones from the same year that do not. I also have Austin version of items that are identical to their Whelen version, but two Whelen items that have differences. Power supplies seemed to evolve in the three or four major steps you outlined with the patents. It's interesting to see the small changes in between. I have lots of older beacons I should check out the internals on.

 

[RS485]

Here's a UPS 52 (made ~1990) and an "AUSTIN MODEL -RS-" (made ~91):

Zooming in the boards:

The UPS-52 was double-flash two-outlet PS with two user-exposed options:Low-power and "Rapid Rate" flash pattern which seems like double flash with no extra time between sides.

The "-RS-" is double-flash but doesn't have any user-exposed options (not even low-power)

Both boards seem very similar but the option-sensing circuitry is simply not built out in the "-RS-". While the power transformer looks different, the part numbers appear the same ("PAC 66207") however the newer board has an extra diode and resistor.

Interestingly, the options circuitry uses the same "H11A1" opto-coupler as the Diagnostics I/O board "01-0266955-00C" we encountered recently.

Also of interest, it looks like the UPS52 and "-RS-" share their hybrid board with a "Galls"-rebranded DashMasterII (ca. 2000):

They look very similar and if they are identical, then one should be able to actuate the "Rapid-Rate".
(I do an experiment)
Of course! If I turn the speed knob to its max position on the DashMasterII, it _is_ effectively "Rapid Rate" where there's no additional time between each double-flash (i.e. LLRRLLRR rather than LL...RR...LL...RR). Same for the "-RS-"

After measuring resistance at the speed knob, the higher the resistance, the slower flash the frash-rate.

So the only thing special in the UPS52 (compared to the "-RS-" is a few more components soldered in to expose a direct-route to lower the resistance whatever's going to PIN # 3 of the hybrid-board...and the equivalent for low-power control.

Not sure yet what the extra "fast diode" and resister do in the "-RS-".

Maybe the biggest difference between the two was the heavy aluminum housing for the UPS52 compared to the simple plastic housing on the "-RS-" (and maybe the price )

(edit): Also, there was an interesting little sticker on the bottom of the UPS52:

 

[JohnMarcson]

Here's a UPS 52 (made ~1990) and an "AUSTIN MODEL -RS-" (made ~91):
View attachment 236091
Zooming in the boards:
View attachment 236092
The UPS-52 was double-flash two-outlet PS with two user-exposed options:Low-power and "Rapid Rate" flash pattern which seems like double flash with no extra time between sides.

The "-RS-" is double-flash but doesn't have any user-exposed options (not even low-power)

Both boards seem very similar but the option-sensing circuitry is simply not built out in the "-RS-". While the power transformer looks different, the part numbers appear the same ("PAC 66207") however the newer board has an extra diode and resistor.

Interestingly, the options circuitry uses the same "H11A1" opto-coupler as the Diagnostics I/O board "01-0266955-00C" we encountered recently.

Also of interest, it looks like the UPS52 and "-RS-" share their hybrid board with a "Galls"-rebranded DashMasterII (ca. 2000):
View attachment 236094
They look very similar and if they are identical, then one should be able to actuate the "Rapid-Rate".
(I do an experiment)
Of course! If I turn the speed knob to its max position on the DashMasterII, it _is_ effectively "Rapid Rate" where there's no additional time between each double-flash (i.e. LLRRLLRR rather than LL...RR...LL...RR). Same for the "-RS-"

After measuring resistance at the speed knob, the higher the resistance, the slower flash the frash-rate.

So the only thing special in the UPS52 (compared to the "-RS-" is a few more components soldered in to expose a direct-route to lower the resistance whatever's going to PIN # 3 of the hybrid-board...and the equivalent for low-power control.

Not sure yet what the extra "fast diode" and resister do in the "-RS-".

Maybe the biggest difference between the two was the heavy aluminum housing for the UPS52 compared to the simple plastic housing on the "-RS-" (and maybe the price )

(edit): Also, there was an interesting little sticker on the bottom of the UPS52:
View attachment 236096

I have a lot of power supplies to open up.... I have lots of duplicates ready to sacrifice. This is very interesting analysis.

 

[shues]

Also, there was an interesting little sticker on the bottom of the UPS52:
View attachment 236096

Rapid rats?! I know the sticker says rapid rate, but the preview makes it look otherwise.

 

[RS485]

Rapid rats?! I know the sticker says rapid rate, but the preview makes it look otherwise.

This is the best I can do (with a Jewler's magnifier and an iPad): If there were just a few more scratches on the "P" of "RAPID", we'd be looking at "RABID RATS"

 

[JohnMarcson]

Rapid rats?! I know the sticker says rapid rate, but the preview makes it look otherwise.

You haven't used infected vermin as a traffic clearing device? I mean of course CA doesn't allow it but around other parts of the country throwing plague rats at cars refusing yield was standard practice in the 1990s.

 

[RS485]

Digging a bit more into the hybrid board...
Here's an aircraft PS "A414A" from about the same time period (mfg in '91):

(note the board (C) of 1989)

It looks to be functionally similar to the "-RS-" - no low-power, no options of any kind. For an aircraft power supply that seems to be expected.

The "A414A" has a visibly beefier transformer and storage caps but otherwise, it seems like the same basic design and it also contains the same hybrid board:


I managed to break the hybrid board up from conformal coating to reveal its part #, then did the same with the UPS52. Same part number and rev level!


I also confirmed that pegging the speed knob counter-clockwise, caused the aircraft power supply to go "RAPID RATE". So it looks like there's a lot in common between these samples yet they're aimed at different markets and price-points.

 

[JohnMarcson]

Digging a bit more into the hybrid board...
Here's an aircraft PS "A414A" from about the same time period (mfg in '91):
View attachment 236102
(note the board (C) of 1989)

It looks to be functionally similar to the "-RS-" - no low-power, no options of any kind. For an aircraft power supply that seems to be expected.

The "A414A" has a visibly beefier transformer and storage caps but otherwise, it seems like the same basic design and it also contains the same hybrid board:
View attachment 236103

I managed to break the hybrid board up from conformal coating to reveal its part #, then did the same with the UPS52. Same part number and rev level!
View attachment 236104

I also confirmed that pegging the speed knob counter-clockwise, caused the aircraft power supply to go "RAPID RATE". So it looks like there's a lot in common between these samples yet they're aimed at different markets and price-points.

I suppose it would make sense to have as much overlap as possible, that would keep costs down. I keep getting outbid on "cheap" aircraft supplies on ebay, I've wanted to open one. The hybrid boards keeping a part number while looking so different is surprising.

User ur20v discovered that the power supply for the par 36 respond-a-strobe looks a lot like an Austin 1510 beacon, including the squared off sides, although probably a slightly older model beacon (which had holes in the center for the older round pinned tubes). The board style and size as well as the mount are the same, just turned in mounting orientation. I also noted that while I cannot find them listed as an option, I have self contained "respond-a-strobe type" rear strobes in one of my very late model 80h bars.

I'm interested in what else was "cross used" on platforms and between products and Austin and Whelen.

 

[RS485]

Here's an Austin model "19S-AP" (dome pictured is _not_ original. Original was "FRONT>"-style asymetric):


I converted this from a single-flash to double -- by doing exactly what Whelen did at the time. I had an "Austin" equivalent of Whelen "DMS" which was already double-flash. Both boards appeared identical...except the trigger circuit. In the "single-flash" case, it had an SCR soldered in but in the "double-flash" case, it was a TRIAC.

Quoting patent '507:
"Timer pin 3 is coupled, via a differentiator circuit comprising capacitor C8 and resistor R19, to the gate of a triac 28. The differentiator generates pulses, for application to triac 28, which correspond to the leading and trailing edges of the signal which appears at output pin 3 of timer 26 as its internal flip-flop is set and reset."

Point being, an SCR will only fire on the leading edge. a TRIAC will fire on both leading and trailing.

So it seems that's all it took for Whelen to offer both single/double in the Austin line at the time. There might be more to this story but I don't have the means to explore it further at the moment.

Also, comparing this to a Whelen 800 at around the same time -- it looks like the main power transistor isn't physically as beefy:



Side note: That 80h is awesome looking! I love the amber cutout within the red lens!

 

[JohnMarcson]

Here's an Austin model "19S-AP" (dome pictured is _not_ original. Original was "FRONT>"-style asymetric):
View attachment 236119

I converted this from a single-flash to double -- by doing exactly what Whelen did at the time. I had an "Austin" equivalent of Whelen "DMS" which was already double-flash. Both boards appeared identical...except the trigger circuit. In the "single-flash" case, it had an SCR soldered in but in the "double-flash" case, it was a TRIAC.

Quoting patent '507:
"Timer pin 3 is coupled, via a differentiator circuit comprising capacitor C8 and resistor R19, to the gate of a triac 28. The differentiator generates pulses, for application to triac 28, which correspond to the leading and trailing edges of the signal which appears at output pin 3 of timer 26 as its internal flip-flop is set and reset."

Point being, an SCR will only fire on the leading edge. a TRIAC will fire on both leading and trailing.

So it seems that's all it took for Whelen to offer both single/double in the Austin line at the time. There might be more to this story but I don't have the means to explore it further at the moment.

Also, comparing this to a Whelen 800 at around the same time -- it looks like the main power transistor isn't physically as beefy:

View attachment 236120

Side note: That 80h is awesome looking! I love the amber cutout within the red lens!

Nice, that makes a lot of sense, that explains the advancement to double flash. The debut of comet flash took a while, looking at the info you had posted previously I'm assuming that update wasn't as simple as using both leading and trailing ends of an impulse, although admittedly I'm not well versed in electronics enough to fully "decode" that.

The 80h was a very late bar, open end domes, gasketed center speaker, slightly different wires feeding the rotators and the stand alone par 36s were all things I hadn't seen in other 80h bars. I will get a better video, but here is my existing one. The strobes a tough to see but they are not synched or linked in any way. The PAR36s could be added to a fully loaded bar whereas putting in the standard linked larger inboard strobes took up a rotator spot.

 

[ur20v]

@JohnMarcson it sounds like you have a model 80H-5 which could be ordered with a pair of forward *or rearward* facing par36 strobes mounted behind the v-mirror.

 

[JohnMarcson]

@JohnMarcson it sounds like you have a model 80H-5 which could be ordered with a pair of forward *or rearward* facing par36 strobes mounted behind the v-mirror.

That is my understanding, except by that point it was the model 81-H technically which denoted the open end domes etc. I just didn't realize "pair" meant unsynchronized with their own power supplies. This option was only seen the last year-ish of the bars 1988-89. By 1990, a year after the option was offered, the 81h (and the whole 8000 / 90 / 80 line) was special order only, then gone.

 

[RS485]

John, getting back to your 5000 PS:

Are the X/Y dimensions about 3-1/8" x 3" ?
If so, this board would fit in a standalone aircraft beacon like this:

The rounded off corners would would be consistent with that too.
I don't recognize the PCB though...and the bolt pattern doesn't agree with the the mounting brackets I've seen so I'm wondering what else your PS might have fit into.

 

[JohnMarcson]

John, getting back to your 5000 PS:
View attachment 236173
Are the X/Y dimensions about 3-1/8" x 3" ?
If so, this board would fit in a standalone aircraft beacon like this:
View attachment 236174
The rounded off corners would would be consistent with that too.
I don't recognize the PCB though...and the bolt pattern doesn't agree with the the mounting brackets I've seen so I'm wondering what else your PS might have fit into.

I am guessing that it was designed to fit into the smaller 1000 beacon previously posted. I also saw a similar size and shape in the original M80 motorcycle beacon, which was basically an aircraft beacon. The "cut corners" look very similar to the internals of the smaller M80 and previous "M" light which were basically aircraft beacons. I haven't seen this particular board in any of my other current lights, but the glass 5000 is my oldest strobe right now. I will measure it when I get home. It doesn't seem to be close to the next oldest 5000 I have which is a much more standard supply. I was also surprised at the "non-enclosed" nature of the supply considering there is no sign of any cover having been there and the bottom of the beacon is open. I have a model M80 on order, we can compare that when it arrives.

I also dug out my "power supply graveyard" which is my box of non-working or incomplete supplies. I will photograph those too, I think there are a few interesting ones, and some other not so interesting ones.

 

[RS485]

I finally found it!

I knew I'd seen that PCB before

This does measure about 3x3-1/4. This was originally in an aluminum box (still looking for it) and was an aircraft PS. I powers up but doesn't flash (yet )

This is the oldest Whelen PS I have but there's no hint of a date on any of the parts. It looks pretty much like what US3515973 describes.

 

[JohnMarcson]

I finally found it!
View attachment 236181
I knew I'd seen that PCB before

This does measure about 3x3-1/4. This was originally in an aluminum box (still looking for it) and was an aircraft PS. I powers up but doesn't flash (yet )

This is the oldest Whelen PS I have but there's no hint of a date on any of the parts. It looks pretty much like what US35515973 describes.

Nice. It has to be a common part between aircraft and early vehicle strobes. The glass 5000 I have is extremely early, it predates any documentation I have. That's why I am hoping dmathieu can post his document that lists his 1000. Whelen started with the rotating rotabeam and strobes were a bit later. As I understand it "Whelen began researching strobe light technology in order to introduce affordable, reliable and highly effective strobe products to the light aircraft industry and then to the automotive market." That was about 1962-63. The first power supplies were probably shared between the markets. Between the early 1960s and 1970s the tech diverged a bit with the crossbars and 6000 bars. I like the fact that the aircraft and emergency vehicle crossover didn't end there and can be seen moving forward too.

 

[dmathieu]

John and Ken, this is a power supply that I'm holding to fit one of the for sale crossbars/3300 Series. Am I correct? What say you?

 

[RS485]

John and Ken, this is a power supply that I'm holding to fit one of the for sale crossbars/3300 Series. Am I correct? What say you?

Looks correct to me...except it has the non-cast base (spun?). I *remember* that! That was on one of the bars I got from Central Eqp in Millis way back when!

In theory, you should be able to drill out the two rivets there in the base and (hopefully) they'll match two holes in the cast base you have. By my measuring, they look to be about 3-1/4".

The transformer should also match the cast base at about 2-3/4"

Wicked cool, man!

UPDATE: I don't see a push-button switch. At some point, that was added to enable low-power mode. If the crossbar expects that (i.e. if there's a hole cutout in the ring) then this power supply might pre-date the lightbar.

Given that it has two transistors, I'd guess it was made before the '507 patent (i.e. early to mid '70s).

 

[JohnMarcson]

Looks correct to me...except it has the non-cast base (spun?). I *remember* that! That was on one of the bars I got from Central Eqp in Millis way back when!

In theory, you should be able to drill out the two rivets there in the base and (hopefully) they'll match two holes in the case base you have. By my measuring, they look to be about 3-1/4".

The transformer should also match the cast base at about 2-3/4"

Wicked cool, man!

The rivets kind of threw me off, but if it fits into the base it should be correct.

 

[dmathieu]

The only pics, info that I have on the 1000. From 1968 and 1969 Darley catalogs. Then the switch to 1200.

 

[JohnMarcson]

The only pics, info that I have on the 1000. From 1968 and 1969 Darley catalogs. Then the switch to 1200.

That is really good info. Thanks for posting the catalogs.

 

[JohnMarcson]

As promised, the power supply graveyard. I think I have a few more somewhere. There is a late 90s super strobe, two "pie pans", an 1980s edge, an unknown 1200 sized beacon, two different year single dashmasters, and a newer beacon.

 

[RS485]

One of those pie plates is intriguing (the one showing the solder/backside of the PCB). I don't think I've seen one like it before. Is there anything special about?

Here's a bit of an oddball:

It came with a cable matching the color-coded stick-ons:

Seems the only thing "special" about it is the photo-cell connection which has a what looks like a special daughter-board to handle the photo-cell port.

 

[shues]

Is the Indiana one the first three-outlet suppy in the thread so far?

 

[RS485]

Is the Indiana one the first three-outlet suppy in the thread so far?

Yes, I believe it is.

 

[shues]

I'd say that fact makes it somewhat special. Most multi-outlet strobe power supplies are designed to run an even number of lightheads.

Edit: This appears to have been my 10,000th post!

 

[RS485]

I'd say that fact makes it somewhat special. Most multi-outlet strobe power supplies are designed to run an even number of lightheads.

Edit: This appears to have been my 10,000th post!

Congrats to 10K!!!!

 

[RS485]

I'd say that fact makes it somewhat special. Most multi-outlet strobe power supplies are designed to run an even number of lightheads.

Edit: This appears to have been my 10,000th post!

I'm not sure it's that special...left is an automotive UPS, right is aircraft.
To me, Whelen lays out that even though you have 4 ports to plug into, you'll only get N joules of flash out of each channel. "Do what you will with it"

In the case of the Indiana PS, it seems like they just burned up a port for the photocell connection and settled on the "3 light system" as shown in the possibilities described in the general-purpose PSs.

That said, I swear back in the day, I saw a municipal truck with one 360 head, and two sealed-beams...and it flashed:
LEFT....CENTER....RIGHT....CENTER...(repeat).

That, to me, was a true 3-light system as it had two levels of "alternating".

 

[JohnMarcson]

I can take some closer pics of the pie pans, I'll probably send them with the one you offered to repair for me, you can have them if you like for experimentation or whatever.

 

[RS485]

I finally found it!
View attachment 236181
I knew I'd seen that PCB before

This does measure about 3x3-1/4. This was originally in an aluminum box (still looking for it) and was an aircraft PS. I powers up but doesn't flash (yet )

This is the oldest Whelen PS I have but there's no hint of a date on any of the parts. It looks pretty much like what US3515973 describes.

I finally got this flashing and found the original capacitors ("Sprague" "Compulytic") and they do appear to have a date code, "6747" which I believe is 47th week of 1967.

This is the only remote Whelen PS I have that does not include a trigger circuit. Exactly as US3515973 shows, the circuit only produces a tiny timing pulse delivered elsewhere.

@John unless I'm missing something, you should be able to observe a small circuit near the flash tube in your 5000. It might look like this (marked "AEI 102" on the other side):

 

[JohnMarcson]

I finally got this flashing and found the original capacitors ("Sprague" "Compulytic") and they do appear to have a date code, "6747" which I believe is 47th week of 1967.

This is the only remote Whelen PS I have that does not include a trigger circuit. Exactly as US3515973 shows, the circuit only produces a tiny timing pulse delivered elsewhere.

@John unless I'm missing something, you should be able to observe a small circuit near the flash tube in your 5000. It might look like this (marked "AEI 102" on the other side):
View attachment 236297

I will check that out. I also just got my M8* strobe and I want to open that. First day I have off I will send you that dead supply etc. Any idea why the blue M80 is 48vdc?

 

[RS485]

I will check that out. I also just got my M8* strobe and I want to open that. First day I have off I will send you that dead supply etc. Any idea why the blue M80 is 48vdc?

View attachment 236304

This is just a guess but maybe either a) 48vdc is in industrial automation sometimes or b) Bell System. I have some '90s era post-Ma-Bell eqp that runs on 48v (with batter backup too).

 

[JohnMarcson]

This is just a guess but maybe either a) 48vdc is in industrial automation sometimes or b) Bell System. I have some '90s era post-Ma-Bell eqp that runs on 48v (with batter backup too).

I will see what is in it and if it has a date. Industrial is probably the right idea. I was thinking a fire suppression system, I want to say the halon system that we looked for training years ago was 48vdc. I also know the solar array that we trained to respond on has 48vdc portions. I don't know of any vehicle that uses 48vdc. It has to be something industrial or stationary. I will compare the supply to my explosion proof 120vac and 24vdc industrial beacons. I might have another 48vdc light from Whelen but I think it is explosion proof rotating.