Federal Signal 500AT Prototype?

[FahmiRBLX]

I remembered the moment I saw a presumably a Federal Signal 500AT Prototype in a YouTube video (I said "presumably" since IIRC the title said about the particular siren) but failed to relocate it at both Google Images & YT. The siren has a short horn, just like the series A and/or B we know and hunt for, but with a diameter of roughly a height of 2 average American adult standing on each other (If an average Southeast Asian adult, then around 3 or 4 of them), has 8 support bars placed in (About the same manner of the A or B (?) series 500) and seemingly has no clear evidence of rotating due to the fact it was held up a support.

Has anyone have more detail on those units such as surviving units, videos of one sounding, more pictures, ads, etc. & additional info regarding on the unit?

Making this as the grand, dedicated 500 series discussion is fine. Other details on other 500 series prototype than the stated above is welcome, but still, try not to go too offtopic.

[Darley Champion]

There was also this gigantic 500 siren prototype picture that "J" posted (long story... PM me for details to not to derail the topic) I think this is what you're referring to...

Sadly I think this prototype was long scrapped by then and even so the guy who posted the picture has long disappeared (or are they still silently lurking this board). So consider this picture lost.

[Siren_Dude]

I believe this is it

[Darley Champion]

Yes! This is the only known photo of the 500 prototype that I was referring to.

[FahmiRBLX]

I believe this is it

Absolutely this one. Great find!

[Tyler]

I wonder what year that was. Looks like it's possibly late 40s given the old Federal Electric branding. Makes me wonder if there were 2 design teams working towards a rotating siren, one on Thunderbolt, one on 500.

[FahmiRBLX]

Long story... PM me for details to not to derail the topic.

Feel free to post the details here. I bet many others went very curious at this time.

[Siren_Dude]

I believe this is it

Absolutely this one. Great find!

I have a tone of pictures saved over the years

[Darley Champion]

Long story... PM me for details to not to derail the topic.

Feel free to post the details here. I bet many others went very curious at this time.

I'm not going to lie, I don't remember much about that... Incident.

All I can recall, it involved a disagreement of some sort on the grounds of Trade secrets or something like that, of course this happened behind closed doors, all I know is what seeped through... So take that with a grain of salt.

[Model L]

I forgot about this image. that thing is huge! apparently didn't work very well though.