Uninterruptible power supply with battery recharging ability. Indication is built around opamp that monitors 12V input DC voltage (blue LED is on). Capacitor emulates a rechargeable battery and charged from 12VDC power supply. When 12VDC supply is disrupted, circuit switches source to the battery so the red LED turns on. Circuit runs on a battery till main 12VDC supply is back or until battery is fully drained out.
