FIGnition FUZE Hardware Reference Manual page 24

Fig 4.3
When 5v is output from the capacitor, the voltage on the output of D6 rises to 5v; the ca-
pacitor charges by 5v producing a 7.5v transition on the output which is heard as a click.
The capacitor then discharges returning the voltage back to 0v [Fig 4.4].