Previous information that was listed on this page was incorrect. In return, I have done a major edit of this page.

A telephone controllable relay was used. If the number that the device was assigned to was called, the relay would switch, setting off the siren.

The 6000R's design is quite similar to the 3016 in my opinion. Both have speaker drivers in a back panel connecting to a triangular-rectangle shaped horn via several cone shaped tubes.

Wow, I never really looked at these before. Looks like ACA ripped off these patents pretty hard with their rotating Alertronics. Didn't the Alertronic directional sirens come out before the Whelen 3000s? I read somewhere that they had copied ACA's design. the thing about design copying I think you ...

I imagine these units are used for notification regarding the tunnel?

Tyler wrote: Wow, I never really looked at these before. Looks like ACA ripped off these patents pretty hard with their rotating Alertronics.

Didn't the Alertronic directional sirens come out before the Whelen 3000s? I read somewhere that they had copied ACA's design.

After doing some research I had found that the GE Powercall siren had the Alert feature as well. Was the Alert signal dedicated for emergency alerting? Or was it used for other purposes?

I know, but there was a dedicated button for it on the siren units themselves.

A while back I was looking at local Emergency Planning documents, and I found something intriguing I've never seen before. In areas that aren't served by A Fixed Siren, Emergency Vehicles would be driving with their sirens producing A Steady "Alert" tone. I've never seen a vehicle siren wi...

They did use polarity reversal to make a yelp signal. In the manual of the Allertor and Screamer, it said the 3rd signal would be such. For the rotator, they might've used a separate motor.

How rare are ACA sirens with the yelp tone capability anyways?