LED emergency light circuit diagram
Phone line LED light:
Also known as free Electric light (that is, the Burmese light commonly known by online sellers), because it uses the incoming line voltage of ordinary household landline phones as power supply, no battery or AC mains is required, and the crystal head at the rear is inserted into the telephone extension interface to illuminate without paying extra electricity. And don’t worry about power outages. In addition, it can also be used as a flashing light for incoming calls. It reminds the elderly with poor hearing to answer the phone in time, because the LED light will go out after the phone is off-hook, it can also help you find out whether the phone has been stolen by others, and it also has certain lightning protection. hit protection. However, because this product uses the power supply of the telecommunications room to which the telephone belongs, if the current is too large, it will inevitably affect the telephone dialing and fax sending and receiving, especially when ADSL broadband users dial up the Internet, it is easy to cause frequent disconnection. Figure 3 is the working principle diagram of the telephone line LED light circuit. The 36V or 48V telephone line DC voltage is applied to the LED after a 10kΩ current limiting resistor and 4 diodes (or rectifier bridges) for polarity conversion. When the telephone feed voltage When it is 36V, the measured working current is about 1.2mA, and the brightness is low. When the current limiting resistor is changed to 5.6kΩ, the working current is increased to 2.1mA: the brightness is slightly increased.
Considering that the LED light of the telephone line has an adverse effect on the Internet and cannot be connected to the telephone line frequently, the author has carried out some modifications to the light. The circuit schematic diagram after the modification is shown in Figure 4. Change the 6 LEDs in the middle to parallel, and add a 3.6V mobile phone lithium-ion battery at the same time, usually use the built-in new lithium battery to work, when the current limiting resistance is 5.6Ω, the working current is about 120mA, and the brightness is relatively satisfactory. In case of emergency, it can still be used to insert the telephone extension interface for lighting. The working current after the transformation is about 4.6mA, and the brightness is reasonable.
The LED lamp with its own lead-acid battery can be charged:
The working principle diagram of the circuit drawn according to the actual object is shown in Figure 5. The 220V AC power supply After the electricity is stepped down by the capacitor and rectified by the diode, the lead-acid battery is charged, and the red LED is used for charging indication. After charging and using, close the button switch K, it will first turn on the 3 colored flashing LEDs, giving off a dreamy and unpredictable colorful light, adding some life fun at night, and then pressing the switch K will turn off the colored flashing LEDs, and then Press again to turn on 24 high-brightness LEDs connected in parallel. Due to the large number, the lighting effect is very good.
When the lead-acid battery voltage is 4V, the actual measured working current of the lantern is about 60mA, and the high-brightness LED current reaches more than 600mA. Such a large current not only makes the lighting time not too long after each full charge, but also damages the internal structure of the battery and shortens its service life. When the test selects 1.2Ω, the working current is finally reduced to 320mA, and the brightness change is not obvious. Because the lamp has not changed much, the circuit schematic diagram after the transformation is omitted.
Through the above analysis, it is found that most of the various LED lamp circuits on the market are too simple. Although the price is very cheap, it will still cause energy waste objectively. It has the advantages of economy and portability, and effectively improves the safety and reliability of use.
