Is this N-channel mosfet wired right?
If signal is detected by the mosfet, i want it to turn on.
Yeah, although the MOSFET will not really "detect" a signal as such. However, if you pull its gate high, it will start to conduct alright.
Wether your MOSFET will survive depends on whether the kickback diode that you omitted is necessary. I'd include it for good measure.
Is the sirene piezo or inductive?
Why do you mean? Why can 't the mosfet detect a signal?
And yes, it's a 5V piezo sirene.
Technically the 10k pull-down resistor should go to the other end of the 220R resistor, but it probably wont cause any change to operation in this case.
The mosfet is not strictly a logic-level device either, but Vgs is low enough that it should work OK, so I wouldnt worry about changing that if you already have it. (I think - given that I am not a mosfet expert)
I would have chosen the IRL3705 if you want to stay with the same manufacturer/series.
There's always the good old MTP3055L if you can get them.
Okay.
My problem is following:
When the mosfet Gate has 5V (i have measured) the sirene does not turn on. When i measure sirene output i get 0V.
Just wondering why this happend...
It's probably a bad MOSFET.
That is an old MOSFET that is no longer manufactured. You may have a fake or a really old part that was damaged.
What is the voltage at the MOSFET drain when the gate is 5V?
0V. No reading at all...
Interesting, first grab the data sheet for the MOSFET you are using. Then look for a Vgs chart usually at the end. Now place your ground lead to the source of the MOSFET (That is the reference point for both P and N devices). Now measure the gate voltage. For the MOSFET to turn on it has to exceed the Vgs voltage. For a N-Channel it needs to be positive, for a P-Channel it needs to be negative.
Your drive circuit is also wrong, the 10K resistors belongs on the port pin, the way you have it is a voltage divider.
Take the measurements using the Source as the reference point and let us know what you have. I expect you will get about a + 3.2V.
Is the siren good?
Does it work if you put 5V and ground to it.
Or does it need a square wave to make it work?
Remove the siren
Put a 220 resistor in it's place.
With the gate 0V, the drain should be 5V
With the gate 5V, the drain should be 0V
Hi, @Bjerknez
Can you please measure the voltages at A, B, C, and D with respect to gnd.
With and without 5V to the gate.
Can you post some images of your project?
So we can see your component layout.
Thanks.. Tom.. 
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When signal to gate:
A= 4.99V
B= 4.88V
C= 0V
D= 0V
When no signal:
A= 0V
B= 0V
C= 0V
D= 0V
Here is datacheet for Mosfet i using:
The sirene works fine and its LOUD!
With 0 volts at point āDā you have no 5 volts applied to the siren. Looking at your photo it appears that the siren is separate from the rest of the circuit. Check all of your connections and wires for continuity. There should be 5 volts af āDā at all times.
5V to siren is an output from mosfet. If the mosfet is not working when signal is given to the gate there is no 5V to "D"?
The MOSFET's function is to supply a path to ground when it is active. It can never supply 5V.
Off course. You've right.
Its wery strange that i don't get 5V to "D" when i power the board with 5V. The chematic over is the same as PCB that i ordered form JLCPCB.
I will measure continuity to morrom between 5V input and 5V to siren.
With the power removed, check for continuity between point D and pin 1 on P1.
Please upload an image of the PCB design. Maybe you forgot to route one trace.