Police Siren Amplifier

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OlivePizza

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Joined 2020
#1
Hello everyone,
Im pretty new to amplifiers and all this, but some time ago I wanted to make a police siren amplifier (only the electronic air horn part) for my car. So I researched a little bit on the internet and was able to find schematics of some 80s and 90s siren amplifiers. With these I was able to recreate the exact air horn sound I wanted but now that I have the sound generated I dont know how to amplify it.
The Airhorn sound is a square wave of around 500 Hz and 10 Vpp.
I have an 100W 11Ohm and two 70W 8Ohm siren speakers.
Here is the schematic of the amplifier that is used by the original siren.

amp.jpg

The design uses some kind of push pull amplifier which i cant get my head around.

My question now is if anyone can help me understand this amplifier or recommend me other designs that could work in a car, like a Class D amplifier maybe.

Thank you all

Best Regards
 
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#2
If you have a signal, you can use virtually any full range amplifier.

Full range class D amplifiers are available but generally not as cheap as class B or class AB amps.


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#4
What's your budget, where are you located, are you opposed to buying used?

There's an absurd amount of used gear out there that will do exactly what you want at very low prices.

Also, I'm not sure you need the full 100 watts. What is it, double the power for a 3db increase?
 
#6
Thats true, I wouldnt mind using the 8 ohm 70 watt speaker aswell.
Im located in germany so used from the US isn't the best solution but if you can point me in the right direction I would know what to look for on the used market here.
 
#7
That complicates things slightly as the brands in the EU are quite different from what is sold in the US.

I would look for a 2 channel amp that can be bridged with an output of 100 - 200 watts RMS. These are typically quite inexpensive on the used market in the US, my guess is it would be similar in the EU but that's just a guess.
 
#9
Just a little cautionary note if I may.

Here in australia... using any device that is similar to emergency vehicles (that includes lights, sirens, uniforms, identification, vehicle signage etc) without the proper permits is a federal offence.
The feds do Not take kindly to this offence.

I once saw a pair of 'kids' driving a car, playing with a home made siren.
They thought it was a right laugh.
Up until they were pulled over by the police and put in the back of a patrol car in hand cuffs.
 
#16
OlivePizza said:
Links for used amps in Germany? Im sure you will find good deals in France too.
Click to expand...
It's not to buy directly for germany, it's to have references for amplifiers you have choosen for this application.
analog_sa said:
Class D is perfect for the job. Every time i hear one i freeze😛
Click to expand...
It's also what I plan to use : just look for amplifier board with supply converter included:scratch2:
 
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#17
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