EOWS-115 help needed

[ver tum]

Jon and I are trying to figure out how to correctly hook up a couple of the horns on his EOWS-115 so that we can do a relatively quiet dual tone test in his garage. Yesterday we thought we had two of the horns hooked up right, but we could still only get it to sound single tone. We know it's a dual tone unit because of what the controller sounds like. If anyone can help us, we would greatly appreciate it. We could also use some help in hooking up all twelve of the horns. Thanks.

[CrazyCalvinWilliams]

How did you record those noises without any speakers? Is there a built-in speaker in the box? Like a piezo?

[Mysterious T-Bolt 111]

How did you record those noises without any speakers? Is there a built-in speaker in the box? Like a piezo?

The sound emits from the control's amplifiers. It is stated in the description.

[CrazyCalvinWilliams]

But how does it emit from the amps? I'm confused.

[CDV777-1]

But how does it emit from the amps? I'm confused.

It just does. Maybe the sound comes from the transformers since it's such a high power amp? I can't think of anywhere else in the circuit that might do it. I have a Federal PA 70 siren and back when it used to work the siren sound could clearly be heard from inside the amp when the siren was running with no speaker hooked up.

[CrazyCalvinWilliams]

See, now I get it! i just needed more of a description.

[ver tum]

Thanks FS-Thunderbolt-Man for hijacking this thread...

If anyone has a downloadable EOWS-115 manual or schematic, please post it here. Please only post here if you can help us. Thanks.

[kb4mdz]

OK, I've to 2 count them two EOWS manuals; off the top of my head I don't know the differences between them.

I tried to upload one in this message, but got a file too big error.

Any idea how to do this? One file is about 3.3 meg, the other about 4.3 meg.



Chuk

[Jim Z]

But how does it emit from the amps? I'm confused.

It just does. Maybe the sound comes from the transformers since it's such a high power amp? I can't think of anywhere else in the circuit that might do it. I have a Federal PA 70 siren and back when it used to work the siren sound could clearly be heard from inside the amp when the siren was running with no speaker hooked up.

These amplifiers use inductors in the signal path, either as noise filters or as part of a high-pass or low-pass crossover. When you pass alternating current (which is what an audio signal is) through an inductor at high currents, the coils of the inductor can vibrate and "sing" along with the audio signal passing through. It's the same reason you hear the 60 Hz hum from power transformers.

late last year I was testing a couple of electronic police siren setups for another group in my company, a Federal Signal and a Whelen. I had the controller/amplifier connected to a resistive dummy load instead of the siren speaker, and I could clearly hear the siren signals coming out of the amplifier.

OK, I've to 2 count them two EOWS manuals; off the top of my head I don't know the differences between them.

I tried to upload one in this message, but got a file too big error.

Any idea how to do this? One file is about 3.3 meg, the other about 4.3 meg.

try emailing them to me, I'll put them on my FTP site.

[Taterworks]

If the amplifiers are the Class-D type, using a switch-mode output stage, they contain an output filter to remove the PWM carrier frequency (which would otherwise overheat the drivers with the superimposed but inaudible carrier frequency) and 'reconstruct' the output waveform from the modulated signal, and this filter does contain large and heavy-gauge inductors that can 'sing' as described. Class-D amplification has actually come a long way since these sirens were designed, and many Class-D amps can even match the distortion characteristics of conventional Class-AB designs (the most common type). I think it's unlikely that these amps would be transformer-coupled to the drivers, but it could be done to prevent DC from a failed amp module from blowing the connected driver.

The tone generator may be dual tone, but only one of the tone outputs might be connected to the amplifiers. Try connecting one driver to each of the amplifier outputs, one by one, until you find which modules are feeding which tone, and if they all feed one tone then maybe the tone generator has two channels, one of which is unused in your configuration. If you can figure out which terminals of the tone generator are the signal outputs, you can probably connect the siren driver directly to those outputs and hear a low-level signal at one tone or the other.