Production of emergency lights

The production of simple and practical emergency lights. It can automatically switch power supply during a power outage. During normal power supply, the backup battery is automatically charged and has a charging protection function. Below is an introduction to its working principle. When the power supply is normal, J2 is powered on and closed, and its moving contact is connected to the "N/O (normally open point)". The positive end of the backup battery is connected to the reverse phase end of IC1. IC1 (LM308) and D5, D6 form a voltage comparator, and the reference voltage is determined by D5, D6. Here, a reference voltage of 6.9V is composed of a silicon diode (D5) and a 6.2V voltage regulator diode (D6) to monitor the charging voltage. When the input voltage of pin 2 of IC1 (i.e. battery voltage) is lower than 6.9V, pin 6 of IC1 outputs a high level, T1 conducts, J1 is powered on, and its moving contact is connected to "N/O (normally open point)". The power voltage charges the battery through R2, and LED2 illuminates as a charging indicator. Changing the R2 resistance value can adjust the charging current. As the charging time increases, the voltage of the two pins of IC1 gradually increases. When the voltage is greater than the reference voltage of 6.9V, the six pins of IC1 output a low level, T1 is cut off, J1 loses power, and the charging circuit is disconnected to achieve automatic charging protection function.
When there is a power outage, J2 loses power and its moving contact is connected to the "N/C" (normally closed point). The battery supplies power through the emergency light circuit corresponding to S1, achieving automatic switching function during power outage. S1 is used here to manually cut off the emergency light circuit. The emergency light circuit is composed of IC2 (NE555), T2, T3, T4, X2, etc. IC2 forms a 50Hz signal generator, which outputs a 50Hz signal from the three pins of IC2. T2 inverts and amplifies it to drive the push pull circuits composed of T3, T4, and X2, respectively. On the high-voltage side of X2, 220V AC is induced, causing the fluorescent lamp to light up. The X2 here can directly use a finished power transformer with a secondary voltage of 4.5V and a primary voltage of 220V, and the power is determined by the power of the fluorescent lamp tube. When using, pay attention to adding radiators to T3 and T4.
During production, X1 uses a power transformer with a secondary voltage of 6V/200mA. J1 and J2 select relays with a coil voltage of 6V. Other device choices can refer to the diagram without special requirements. Circuit debugging is very simple. When the main power supply is connected, J2 should act, and LED1 is the power indicator. Then measure whether the voltage of pin 3 of IC1 is around 6.9V, and then use an external power supply to connect to pin 2 of IC1 to adjust the charging protection circuit. When the input voltage is greater than 6.9V, J1 should act to disconnect. Short open S1 and connect it to the emergency light circuit with an external power source. Measure whether the output of IC2 is 50Hz, and then measure whether the voltage of X2 output is around 220V. LED3 is a power outage/emergency light operation indicator.