Timer for a buzzer

[Melkor6000]

As part of a recent electronics project, I included a piezo buzzer, which I want to have buzz for about a second, and then stop.

I have tried using a 555 timer in monostable mode, but that doesn't work, since the voltage that triggers the buzz is continuous (I gather from other reading that a monostable oscillator only works when the lifetime of the trigger voltage is shorter than the discharge time.)

Is there a way to put something in-line with the buzzer, which causes a continuous voltage to become a ~1 second pulse? It would need to be able to do this time after time (a reset button is an option, since I have space for it on the console).

Thanks, and please respond if something is unclear in my question.

 

[(*steve*)]

Place a capacitor between the "continuous voltage" and the trigger pin of the 555.

That way, whenever the voltage turns off, a brief pulse will set off the monostable.

See here. Note that you need a negative going transition to trigger the 555.