The post describes a clear-cut mains malfunction backup circuit for offering Arduino boards an uninterruptible supply throughout this kind of circumstances.
The most basic solution to put into practice the offered application is as simple as utilizing two diodes as demonstrated in the above diagram.
The layout demonstrates two diodes with their cathodes associated collectively and anodes terminated to a 14 V source and anodes to the positive of a 12 V battery source respectively. The typical cathodes of the diodes are additional hooked up to a IC 7805 IC whose output is lastly put on to the Arduino board.
When mains exists the 14 V supply guarantees s continuous trickle charge supply to the connected battery via R1 as well as gives the Arduino borad by means of D1 and the 7805 IC.
Within this circumstances D1 cathode encounters a much higher potential than the cathode of D2 due a comparatively lower battery potential at D2 cathode.
The above circumstance maintains D2 reverse one-sided enabling the battery charge to stay blocked and pass only the adapter voltage to the Arduino board.
However the moment the mains provide fails, D1 immediately prevents carrying out and allows D2 to get forward not balanced to ensure that now the battery immediately requires over and starts providing the Arduino via the 7805 IC.