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Police Siren Modifications

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Suraj143

Active Member
Hi I made the below siren.It worked but I'm still not satisfy with the sound.

Help me to fine tune this circuit.

Note that it has not used the pin 3 of the 1st IC.
 

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  • 555 Siren.gif
    555 Siren.gif
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Square waves usually don't sound better.

Boncuk
 
The thing is this is working speedily i need to slow a little bit.

I turn the preset but its effective in the near end.That means if I can turn the preset 180" degrees it will effect only 170" - 180".
 
Use 100µF instead of 47µF for the timing capacitor of the left hand timer IC.

It will change the frequency from 0.318 to 0.149Hz.

Boncuk
 
Hello boncuk i changed the c value to 470uf it worked with the timing that i was expected.
The txo issues are

when power up the sound is very ugly.i think this is due to the charge level of the 470uf cap.how to get a smooth sound when power up?

Still the 1st preset is effective in the near end.so its very hard to tune with a screw driver.
 
Next try 47K instead of 2.2K for the top resistor (VCC -> pin7).

470µF seems to be a very high value. Better experiment with the resistors and limit the timing cap to 100µF.

Boncuk
 
Hi I have changed the below modifications.

Please see is it ok?

When I supply it from an unregulated supply the sound is not smooth.but if I give it from a SMPS it works smoothly.

But still on first time power up the sound is very ugly.Any method to prevent this?
 

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  • Siren Mod.PNG
    Siren Mod.PNG
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