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Re: Haifa, Israel Hörmann F71
Posted: Thu Dec 14, 2017 5:30 pm
by Duderocks5539
Chem_Boffin_6589 wrote: ↑Thu Dec 14, 2017 5:21 pm
Duderocks5539 wrote: ↑Thu Dec 14, 2017 5:17 pm
Does anyone what HTZ these are?
They're DC operated so hertz don't really matter. These sirens use a petrol powered or diesel powered compressor which are started using a deep cycle battery like a car.
No ,I mean what was the frequency these produced.
Re: Haifa, Israel Hörmann F71
Posted: Thu Dec 14, 2017 5:33 pm
by Chem_Boffin_6589
Duderocks5539 wrote: ↑Thu Dec 14, 2017 5:30 pm
Chem_Boffin_6589 wrote: ↑Thu Dec 14, 2017 5:21 pm
Duderocks5539 wrote: ↑Thu Dec 14, 2017 5:17 pm
Does anyone what HTZ these are?
They're DC operated so hertz don't really matter. These sirens use a petrol powered or diesel powered compressor which are started using a deep cycle battery like a car.
No ,I mean what was the frequency these produced.
Maybe you should have asked what the sound frequency is then. Output is meant to be similar or the same as the E-57 who's sound frequency is about 533 Hz I think. Musically the note produced as an A5 (or just the first A note after middle C)
Re: Haifa, Israel Hörmann F71
Posted: Fri Dec 15, 2017 2:25 am
by DJ2226
The E57 is a 9 port siren, so it does 425 Hz when on 50 Hz AC. They do 530 Hz on 60 Hz like a Screamer S-5.
These sirens actually had speed control of some sort on the chopper motor which is why they have such a linear wind up. Battery voltage would only affect how fast the chopper would ramp up. Most of them tended to be somewhere in the 415 Hz or 425 Hz area so long as the batteries were in good condition; if the voltage falls too far below 24 VDC it would have slow wind ups and peak lower than normal just like any typical DC powered siren. When that speed controller or whatever it is gives up the ghost, the chopper will spin up and run at any pitch. Cologne has 273's like that that sound like 508s and T-128's in the distance, roughly 485 Hz at full speed with one that likes to peak out at around 530 Hz.
Re: Haifa, Israel Hörmann F71
Posted: Thu Nov 01, 2018 7:31 pm
by Duderocks5539
Bump. I forgot to ask ,but why do some F-71s have long wind downs?
Re: Haifa, Israel Hörmann F71
Posted: Thu Nov 01, 2018 8:01 pm
by Chem_Boffin_6589
Depends on how good the bearings are versus the air pressure being forced up.
Re: Haifa, Israel Hörmann F71
Posted: Thu Nov 01, 2018 11:42 pm
by Duderocks5539