if you have telephone relays, then buzzing is not an issue. The ones I used years ago would "always" make contact. I used the N.O. contact to apply power to the relay once it received a pulse. I can't tell you now how long the pulse had to be (too long ago). Even if you wired the relay as a buzzer, it still made complete contact before returning to the open position. It would "buzz" at around 10-20hz. You just have to think about what happens while the relay is actuating and all the contacts may be open ( break-before-make ). Otherwise, you'll be making a lot of nice buzzers. More than one phase of clock makes things easier. Dwight