The Siren Board

Darley Champion wrote: ↑

Tue Oct 02, 2018 10:00 am

Travis wrote: ↑

Mon Oct 01, 2018 2:33 pm

There once existed a recording of either an Allertor or Banshee doing this "yelp" signal. From what I understand this was accomplished by changing the polarity of the motor leads to electrically "brake" the motor. I don't know how many units were ordered with that capability, but it would seem this would damage the motor over time.

IIRC Doerr made special motors intended for this yelping signal, that polarity revarsal thing was dropped when ACA started using Baldor motors

It would still mean having to quickly stop the from siren rotating also, which I'd think that would wear out the gear reducer due to it going from 3450 RPM to 0 in only a few seconds.

That too, it would still have pulled a lot of strain, I don't really know much if ACA did indeed used polarity reversal to achieve a yelping signal (only that I've heard long ago from a certain member of the board) but if they wanted to go down that way, they must have designed the reducer so it could take the extra strain... Again ICBW

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?

MaineCivilDefense wrote: ↑

Tue Oct 02, 2018 6:43 pm

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?

I'm going to assume none exist anymore. But I would think that there were some that existed, probably long before my time though.

Yup, I'm not even sure if they ever sold any with the 3rd signal capacity.

Darley Champion wrote: ↑

Wed Oct 03, 2018 5:42 am

Yup, I'm not even sure if they ever sold any with the 3rd signal capacity.

They probably sold until ACA realized that this could damage the siren.

They would know if it damaged it during their own quality control tests surely.

T'was most likely a special order that never caught on... Or technically was too complicated when it came to mass production.

Check page 14: https://wiki.airraidsirens.net/images/c ... Manual.pdf

Pretty much.. I'm not denying this option was never used but rather saying the existing ones were eithier removed or stripped of their "yelping" capacity.