Battery Backup with PIC controlling switch

[Dwayne]

Folks, I am looking for a way to make the PIC chip automatically keep the power on, until I programmically turn it off.

For example. If a person presses a switch to apply the 5 volts to the PIC chip, The chip will start up, and I can programmically flip a pin to toggle the base of a transisor. This transistor will short the manual pin, so that when the person lets go, the voltage will still keep the PIC running. Then after I do what I want, I can toggle that same pin, turning off the power to the PIC chip, and killing the chip until next time. I am attaching a JPEG schematic that is kinda what I am looking for. I need the schematic, transistor, resistor values, and the works. I would like to make it in as few pieces as possible. I would also like to make it have a extremely low current drain, so that the battery can be left on it continuously...like a fire detector.

Dwayne

[Melanie]

Try looking for:-

'Soft' On/Off Power Switch in the General Section from 9 August

and

Electronic 'Soft' Power Switch in this Schematics section from 10 August

Most can be adapted for your needs.

Melanie