Short test of a breadboard siren

[djscrizzle]

I built this siren about a week ago and hooked its output straight to the speaker as to not get too loud. With an amp, this thing gets downright loud...

http://www.youtube.com/watch?v=oVJk0CA1tkI

If I used a Piezo tweeter (like that found in PA cabinets) it has a different sound.

What I did is modified the "typical" wailing siren using 2x LM-555s... I added around 23,000 micro farads in capacitors to provide a wind-down.

There's also a 50K potentiometer on "U1" in place of "R2". A 232-ohm power resistor on the positive power lead offers a slow-ish wind-up by offsetting the inrush current the caps draw. I added 2x 2N3906 wired parallel in place of the 2N5400 on "Q2" using just 1 provides a higher tone. "C1" is a 100uF instead of 470uF.

I also substituted a TLC-555 CMOS timer instead of a LM-555 on "U2" on the provided schematic below.
http://www.uoguelph.ca/~antoon/circ/whooper1.html

[Corey Hudson]

What kind of speaker and amp are you using?

[djscrizzle]

What kind of speaker and amp are you using?

In this test, none. this is straight off the board. If I want more power, I use a Pyramid PA-800X pa amp and 2 piezo compression horn drivers. They get loud. Testing them in the basement later in the afternoon, I'd say they get close to 120 dB at about 440 to 500 Hz...
I use Piezo compression horns because they're immune to burning out like most speakers do. they're also cheaper.

[Corey Hudson]

Piezo compression? Never heard of it.

TO WIKIPEDIA!

EDIT Cant find anything on it? I have a Powerhorn if thats what you mean but it has a coil.

[JasonC]

A piezo speaker is basically a powerful, high pitched tweeter, usually lo-fi but high output.

[Corey Hudson]

Thats cool where did you get it. And for how much. 8 Ohms?

[djscrizzle]

Thats cool where did you get it. And for how much. 8 Ohms?

http://www.mcmelectronics.com/ carries 4x10 Piezo horns... Both compression and one-piece horns. Shouldn't be more than $40 a pop for tweeters like these... They're absolutely lovely for a siren application as they're tough and don't burn out (if your amp puts out a clean, non-clipping signal)

EDIT: They're MCM part # 53-900 for the driver and part# 53-965 for the horn lenses...

The piezos do voice relatively well for mass warning applications where hi-fi is NOT needed...

Power them with at least 100 watts/ driver and you'll get decent SPL figures.
Make sure you're feeding 1-1.5 volts RMS into the amplifier and keep the gain at 75% or less to avoid clipping.
Clipping can kill a speaker of any design by sending DC into the voice coil, heating it up and eventually burning it out.

Piezo compression horns work best wired in Parallel in groups of two per amp output channel.

[djscrizzle]

Piezo compression? Never heard of it.

TO WIKIPEDIA!

EDIT Cant find anything on it? I have a Powerhorn if thats what you mean but it has a coil.

Power horns are great, but you have to be more careful with them as they have a voice coil and can burn out pretty easy if the amp powering them goes into clipping.

Feel free to try my modded siren for yourself... a little experimentation is expected... feel free to bend the circuit and take video if you wish to... I'd like to see other people make these sirens...

[Corey Hudson]

I'm better with circuits, but haven't a clue when i hook up paging amps to speakers!

This is what i have.





1) Does anyone know how to hook it up to a regular 8 Ohm speaker/Powerhorn?

2) Does anyone know how to hook it up to a piezo?

[djscrizzle]

I'm better with circuits, but haven't a clue when i hook up paging amps to speakers!

This is what i have.





1) Does anyone know how to hook it up to a regular 8 Ohm speaker/Powerhorn?

2) Does anyone know how to hook it up to a piezo?

Yes and yes.
Wire the powerhorn to the 4 ohms out. it will have HALF the rated output though due to the Ohm's law applying to loudspeakers.
Piezo speakers are wired in the same as normal coiled speakers.

Your signal input is wired to the signal in, and the common.