Circuit operation principle of the device shown in Figure 11. Power outages are frequent thing, but some occasions, the power does not allow (such as the ongoing surgery, etc.)
. LSE with simple circuit design, fully automated. When 220V AC, the lamp H1 lights up, while the LSE feet high output, transistor VT end, the relay J is released, it does not shine direct light H2. Once a power outage, H1 off, LSEs pin output low, then transistor VT conduction, the relay J pull, turn the power lights H2, H2 light automatically convert between almost two lights interruption.