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 is from a Radio Electronics from October 1970. The circuit uses transistors from that...
This circuit, found in a 1985 documentation, causes two incandescent lamps to flash alternately. The...
This circuit was found in a 1987 edition of the United States' Hands-On Electronics magazine. The...