5v battery backup? Answered
I have a 555 timer circuit running in monostable mode which I need a battery backup for.
Anyone have a simple, reliable circuit that can achieve the following results :
1. Switch power between the 5v cell phone charger and the battery in the event of a power outage. The "switch" needs to be seemless otherwise it will trigger the monostable as it is set to trigger or re-trigger whenever the power goes off and on again.
2. Charge the battery when the power is on.
3. Stop charging the battery when it is fully charged.
Any other suggestions will be much appreciated. I am not rigid on the design and use of parts, although....the cheaper the better without compromising on reliability (of course).
This is for a security system that drives two lasers, a camera and a cell phone. Not sure if the cell phone battery can be used to power the "backup system" as well as run the cell phone.
Thanks in advance.