This schematic is simply a basic system of UPS (uninteruptible power supply). The main schematic gives a continuous regulated 5 Volt result with an not regulated 12 Volt supply. Regarding electricity line fail the battery will take control, without any surges within the regulated supply.
These schematic may possibly customized for the purpose of different regulated and even unregulated voltages with the use of different regulators and rechargeable batteries. For a about 15 Volt regulated supply use a couple of twelve Volt electric batteries using series along with a 7815 regulator. There flexibility on this schematic.
Between terminals VP1 and also VP3 the nominal unregulated supply is available and a 5 Volt regulated supply between VP1 and VP2. Resistor R1 and D1 will be the charging guide for battery pack B1. D1 and also D3 prevent LED1 being lit up under electricity fail conditions. Battery is designed to be trickle charged, charging current defined as :
(VP5 – 0.6 ) / R1
in which VP5 would be the unregulated DC power supply voltage.
D2 must be as part of the circuit, with out D2 the battery would charge from the full supply voltage with no current limit, which would cause damage and overheating for some rechargeable batteries. An electrical power outage is simulated below:
Note that in every case the 5 Volt regulated supply is actually kept constantly, while the unregulated supply will be different a few volts.
The capacity to maintain the regulated supply with no electrical supply determined by the load used from the UPS and also the A/h capacity of the battery pack. If you were working with a 7A/h 12 Volt battery pack and load with the 5 Volt regulator was 0.5 A (and no load via the unregulated supply) the particular regulated supply would be handled for around 14 hours. Higher A/h capacity battery packs gives you an extended standby hours, and vice versa.