Use an active buzzer like this. Then just hook them up in parallel from the same output pin. That's what I did when I made a geiger counter. Put a switch on the buzzer line so you have a bit of quiet.
Use an active buzzer like this. Then just hook them up in parallel from the same output pin. That's what I did when I made a geiger counter. Put a switch on the buzzer line so you have a bit of quiet.