The Siren Board

Very cool! I'm reminded of how danwisbey85 restored a few Carters sirens and did a great job on them.

If you don't mind my asking, how much did it set you back? Hopefully less than a dollar per pound...

so whats the reason behind having more ports if it makes the same sound

Remingtoncountry wrote:so whats the reason behind having more ports if it makes the same sound

I think it lets the motor spin at a slower speed and more ports means less load. It also draws less volts since it runs slower

Remingtoncountry wrote:so whats the reason behind having more ports if it makes the same sound

Comparing my two Carters, the 10/12 (220V, 3Phase) does 3600 RPM with a 13 Amp draw, my 20/24 (220V, 3Phase) does 1800 RPM (or 1500, has two motor tags) with a 14.5 Amp draw. The amount of ports is directly proportional to the motor RPMs, I'm guessing they would have a very similar dB output. So by doubling ports you can get close to the same output with half RPMs VS Less ports and more RPMs. Is there anyone here that may know more about this and can elaborate?

Mark N wrote:I think it lets the motor spin at a slower speed and more ports means less load.

The pitch of a siren is proportional to the number of ports for a given speed, but more ports don't necessarily mean less load. Designing a siren to operate at a certain pitch can be accomplished by a number of port/speed combinations. The load on the motor will depend more on the size of the impeller and the resulting volume of air that it moves.

Mark N wrote: It also draws less volts since it runs slower

Motors don't draw volts, they draw current, which is measured in Amps. The product of voltage applied and current drawn is power, which is measured in Watts. In the case of a three phase induction motor (which I believe this siren has), the speed depends on the line frequency, number of poles, and (to a lesser extent) the slip. The speed is pretty much independent of the voltage.

If the motor is running at half the speed but chopping air twice as many times per revolution, you get the same pitch. This will sound the same as a 2T22.

Awesome find. You sure have a way with rarities!

Siren_Dude wrote:The amount of ports is directly proportional to the motor RPMs, I'm guessing they would have a very similar dB output.

The pitches would be practically identical, but having the motor spin half as fast will still get you a lower output intensity.

Nice Score. I wish there were some like that to be found in my area.

On Sept 11th, I spooled my big "Blues Brothers" CLM up for the opening of the local museum's EMO display.
Had the tripod set up with the camera to record it, but ended up with one still photo instead of any video.
Got the camera issue sorted out this evening, so will see about filming a proper video this weekend.

The Denver Quadruplex is IN the museum display, but a friend recorded a short "phone" video before it was delivered.
I did not know he was going to film it, as I believe he thought it was some sort of "blower", and I only
fired it up to show him how it worked.
He missed the first part of the run up, but did get most of the wind down.
I kind of felt sorry for him, as he was using 2 hands to hold the camera.

The video is at: https://www.facebook.com/photo.php?v=597328556976820

Oy-ving wrote:Nice Score. I wish there were some like that to be found in my area.

On Sept 11th, I spooled my big "Blues Brothers" CLM up for the opening of the local museum's EMO display.
Had the tripod set up with the camera to record it, but ended up with one still photo instead of any video.
Got the camera issue sorted out this evening, so will see about filming a proper video this weekend.

The Denver Quadruplex is IN the museum display, but a friend recorded a short "phone" video before it was delivered.
I did not know he was going to film it, as I believe he thought it was some sort of "blower", and I only
fired it up to show him how it worked.
He missed the first part of the run up, but did get most of the wind down.
I kind of felt sorry for him, as he was using 2 hands to hold the camera.

The video is at: https://www.facebook.com/photo.php?v=597328556976820

Could you get more pictures of the Denver siren? name plate, etc? thanks

There are a couple of photos of the Denver taken last year here: http://www.flickr.com/photos/oy-ving/

I will be at the museum later this week, and can get some new photos of it cleaned up a bit.
The motor may not be original (we think it was 32v DC to start with) but is what powered it when it was taken out of service.

I recorded a video of the CLM yesterday. It is 3 minutes long, and 237 MB in size.
It will not upload to my Flickr page, and I don't have any other "hosted" accounts.
What other service would you suggest? (I'm not very computer skilled, and don't usually do video. No cell phone either.)