I have an application where I need to sound an alarm when the device losses AC power. I was planning on using a 10,000uF 25V electrolytic capacitor to provide backup for the alarm. If the device loses ac power which causes my 3.3 volt supply to drop to 0 volt a FET would activate the alarm which is powered by the capacitor which is charged to 15 volts. The circuit works and the alarm sounds continuously for a few minutes until the capacitor discharges.
I thought to make the alarm last longer I would pulse the alarm for 1 second every 5 seconds. I thought the best way to do this would be a low power 555 timer circuit. But, it has been several years (25 to be exact) since I have used a 555 and thought maybe by now there would be something better, cheaper, ???.
This project is very cost sensitive and the fewer components the better. I basically want a very low power device at very low cost that can run directly off the 15 volt capacitor and keep working until the cap discharges to below about 3 volts. Just looking to see what TI would recommend for me.
