Hi there

I have a 12v door access system that activates a maglock door. I have wired in a new exit door switch (the one with the big green knob). Using one pair of it's blue/red wires I have successfully wired the 12v system so that the closed circuit becomes open when you press the switch.

My question is I want to run a buzzer to the same switch so that the open circuit becomes closed when the button is pressed, the buzzer goes off and announcing that the door lock is off. I know that for this I need to wire the swichtes black/white pair to the buzzer. However what I am not sure of is do I have to a bring a separate 12v supply to the buzzer or by activating the switch the 12v will get diverted to the buzzer?. If I need a separate supply, can I take a spur (sorry for the poor term) from the door switch supply and link it to the buzzer?.

thanks in advance