The Siren Board

Chicagosiren-hunters wrote: ↑

Mon Nov 27, 2017 2:57 am

I have a theory as for the High-Low signal: I remember seeing a siren from a foreign country (I sadly cannot remember where) that ran a "mock-up" High-Low by altering the voltage going to the motor; full speed for the high, and a lower voltage for the low. There may have been a transformer attached to a timer that alternated between full and partial chopper voltages to make a fire signal.

It had a mechanical valve that would open and close. While the valve was closed, it would change in speed

An even better question, was the hi-lo signal regularly used or determined to be used as a ''special'' nuclear accident signal? Or was it just something it could theoretically do?

FS Rotor wrote: ↑

Mon Nov 27, 2017 3:33 am

Chicagosiren-hunters wrote: ↑

Mon Nov 27, 2017 2:57 am

I have a theory as for the High-Low signal: I remember seeing a siren from a foreign country (I sadly cannot remember where) that ran a "mock-up" High-Low by altering the voltage going to the motor; full speed for the high, and a lower voltage for the low. There may have been a transformer attached to a timer that alternated between full and partial chopper voltages to make a fire signal.

The “hi-low” it produced was referring to the sound. It had a mechanical valve that would open and close thus producing high sound output for a few seconds, and low sound output for a few seconds.

In a pneumatic siren that would result in pulse not high low one minute the siren is audible the next minute no sound.

Great find! I had a few pictures, some where, of these.

I wonder if Eclipse8 horns would work? Not having a directional horn does eliminate any rotor drive issues.

Hacksaw wrote: ↑

Mon Nov 27, 2017 4:04 am

Great find! I had a few pictures, some where, of these.

I wonder if Eclipse8 horns would work? Not having a directional horn does eliminate any rotor drive issues.

Me and FS Rotor will be making horns for it ,since I have all the blue prints and the horn designs. The horns were actually made of fiberglass and were 32" long.

FS Rotor wrote: ↑

Mon Nov 27, 2017 3:33 am

Chicagosiren-hunters wrote: ↑

Mon Nov 27, 2017 2:57 am

I have a theory as for the High-Low signal: I remember seeing a siren from a foreign country (I sadly cannot remember where) that ran a "mock-up" High-Low by altering the voltage going to the motor; full speed for the high, and a lower voltage for the low. There may have been a transformer attached to a timer that alternated between full and partial chopper voltages to make a fire signal.

The “hi-low” it produced was referring to the sound. It had a mechanical valve that would open and close thus producing high sound output for a few seconds, and low sound output for a few seconds.

I though I was referring to sound; the full power would make a high tone, and the reduced power would make a low tone, just with a minor wind-up/wind-down in between.

If you look at the spec sheet, you can see that this is, in fact, an unconventional octave-interval siren. It clearly says, "240 AND 480 HZ".

FSThunderboltfan1000 wrote: ↑

Mon Nov 27, 2017 2:33 am

FahmiRBLX wrote: ↑

Mon Nov 27, 2017 1:40 am

So this siren is Hi-Lo Capable? Exited to hear it sound all three signals, but wait, is it Alternate Wail-Capable? In my logic, if it's Hi-Lo Capable, of course it could sound Alternate Wail. And I'm also curious, if this siren works the same manner as a Thunderbolt and a Hurricane, meaning it has a typical Chopper/Rotor w/Stator and a blower to pump in more air?

Not trying to be mean or anything, but take a good look at that rotor on the siren it is a single tone rotor so no this siren will never sound any sort of high low signal. The sirens if rigged right could theoretically be capable of doing pulse, but not high low.

Replying to you, this makes me curious : (Look at the "THREE SIGNAL CAPABILITY" Part)

It's actually not an octave interval siren. The 240 and 480 means that its 240 Hz running with the blower and 480 Hz without the blower.

The two frequencies part intrigues me, I have a problem with it. If this siren was on a typical single phase induction motor it's only going to do one pitch, 250 Hz. Since the rotor is 4 port that only way you can get 480 Hz out of it is if you double its RPM. The only way that could happen is if you increase the frequency of the AC. The only other way you can double the pitch is by doubling the port count on the rotor. With a universal motor you can spin the chopper up to 7200 RPM like you could see with the Deutsch pneumatic sirens, and you can change the speed by changing the voltage with a transformer or using a MOSFET and micro-controller to control it via PWM. With the universal motor concept it's possible to have a high low tone by alternating the voltages or frequency of the PWM. While you can change the speed of the AC motor by changing the frequency, that chopper isn't going any higher than 250 Hz unless you couple it to a VFD and drive the motor at a higher frequency. I have a feeling that the two frequencies list were options for the the siren and hi-lo was pulsed steady.

I wonder what kind of pressure that blower generates. With the design of the chopper having such close tolerances it won't take much to make it punch pretty good. I though it was amazing to see how close they were able to get it with my Model 1 siren, but with this thing it seems that the rotor actually contacts the stator. That's nuts! I wonder if changing the pulley ratio to increase the blower's RPM will make it any louder or swapping it for a roots or screw blower to apply more pressure to the system. It's definitely a one of a kind siren for sure.