Circuit Working Principle: such as photo shows, the closed power switch S1, the normal power supply when the mains voltage of 220V, then the capacitors C1, C2, after blood pressure, VD1-VD4 after full-wave rectifier, regulator VD5 and regulator filter capacitor C3, the resulting stable 11.5V DC voltage and 75mA of current, for the nine 1.2V rechargeable battery, while the work of the relay coil K is energized, the normally closed contact K1 off, LED lights without electricity not bright; the other hand, normally open contact K2 is closed, while switch S1 dial pulse current to the rechargeable battery on the formation of E 11.5V battery float charge. R3 is a current limiting resistor, the battery does not heat the battery voltage to maintain peace in the state, charging current small, that is, they say, the floating charge, the battery life of 1-2 years. LED1 ~ LED24 is a white LED, to a group every three strung, so that may constitute 24 to 8 group, and after the 8 sets of parallel circuit in Figure received. Since the operating voltage of each LED to 3.5V. 3 series for the 10.5V basically meet the requirements. And the work of each LED current between the 25-30mA, which makes each LED can work
Once the mains power circuit fault outage or household fuse blown. Relay coil K stolen electricity. K2 contacts open, when the normally closed contact K1 is closed, turn the power rechargeable battery, LED’s 24 light LED, to provide people with emergency lighting;
The choice of components: Figure in the C1, C2 use 1µF/400V quality polyester capacitors. K use voltage of 10 ~ 12V, current 45mA relay sensitive about, such as the JPX-12F, etc., LED1-LED24 are white light-emitting tubes f5mm’s. E 9 7 1.2V use rechargeable batteries in series, can also be a 12V maintenance-free animal cells. Other selected tagging according to the figure, the condemnation, no special requirements.
Whole circuit is better placed in an insulated plastic box PVC fire, wire leads connected electricity, according to the need to LED1-LED24 placed in many different places is completed.