This circuit that emits siren sound can be used in a fire alarm. We found it in an old American documentation. The signal must be applied to a good audio amplifier.
This circuit was found in Motorola documentation from 1968, using high power transistors and...
Also able to use the LM291, this circuit was found in a Radio Electronics magazine from October 1977....
This circuit generates a linear sawtooth signal. The circuit was found in the December 1992 issue...