Suggested by Intersil in documentation from the 90's, this circuit is valid for modern operating equivalents, including types that operate with low voltages.
A modulated (flashing) siren using the four gates of the 4001 integrated is shown in the figure....
May 2017 - Mouser Electronics already has Microchip's new MCP14A0451 and MCP14A0452 integrated...
Mouser Electronics has in stock Texas Instruments Buck controllers LM5145 to operate with voltage...