We found this circuit in an old Mullard (Philips) documentation on the 555 and 556 integrated circuit (double 555). The relay must be 12 V with contacts that support the horn current.
This circuit was found in a 90s Electronic Engineering. The quadruple operational amplifier can be...
This general-purpose two-transistor circuit was found in the November 1993 issue of Electronics Now. The...
This configuration is suggested by Mullard (Philips) in an old manual of 555 integrated circuits....