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.
Capacitors determine the frequency range together with resistors, and these components can be...
This circuit was found in the June 1970 Radio Electronics magazine. The power to the load is triac...
This circuit has its application suggested in an alarm system. The circuit is from an old RCA...