How can i up the alarm sound?

Other Hardware Audio
1

hi;

i was made a little circuit with arduino.
used a pir sensor, leds and 0,25W 8 ohm little speaker like buzzer.

How can i up the alarm sound?

thanks all, bye.

2

Is the speaker connected to an output pin without resistor ?
You need a resistor of 100 ohm in series with the speaker.

For louder sound, make a box around the speaker, or try a different speaker, or use the toneAC library for double volume. You might even use an amplifier.