Hi
Sorry to dig up an old topic but I have searched for hours and yours is the only topic I could find with a schematic i understand and good explanation of what it does.
Can I ask whether something like a L7805CV will be okay as the 5v regulator?
Also, I am planning on installing this into a car and DC in will come from a separate 10V regulated supply (found in Smiths instrument clusters) so can I use the 9v1 zenner and 100nF stated in an earlier reply or should I use something else?
My use of your circuit is to enable a digital odometer I've made to write back to EEPROM during power down of the car circuits. I am only updating EEPROM so hope this will allow enough time to achieve that.
Many thanks
Luke.