A Few Questions

[Nelso90]

For the port ratios on sirens, simply listen to the audio to discern the 2 tones separately, then find their values in Hz. Multiply the tone by 60 to get pulses per minute, then divide by motor RPM, usually 3450 or 3600 for synchronous motors. T-Bolts are a bit different. I can always tell the 5 port choppers by listening to the dominant tone, and the harmonics of the rotor vibration. I also listen to F1 a lot, and they used to run V10 engines to around 19000 rpm, which sounds quite a bit like a thunderbolt rotor turning 9K.

[whelen4004tech]

actually last thansgiving when i went out to georgia i crossed Talladega county and encountered i believe three whelen WPS-2807's here is a video of one:

http://www.youtube.com/watch?v=Nl81JFWGLN8