This circuit was found in a 2005 Linear Technology component manual. The circuit is full bridge and can operate on bridges up to 75 V. The circuit power is 5 V which allows its use as a shield.
This simple stage can operate with low frequency signals (audio), driving a small lodspeaker....
This 3-digit code switch was obtained from an old American documentation. The capacitor is 470 uF...
A modulated (flashing) siren using the four gates of the 4001 integrated is shown in the figure....