Telephone line power LED light circuit diagram

Also known as the electric light (known as the Burmese lamp commonly used by online sellers), because it uses the incoming line voltage of ordinary household fixed telephones as the power source, without battery or AC mains, the tail crystal head can be inserted into the telephone extension interface to illuminate without another Pay electricity, don't worry about power outages. In addition, it can also double as a telephone call flashing light. It reminds the elderly who are not very good at hearing to answer the phone in time. The LED light will go out after the phone picks up the phone. It can also help you find out if the phone is stolen by others, and also has a certain lightning protection. Hit protection. However, since the product uses the telecom engine room feed power source to which the phone belongs, it is inevitable that the current demand is too large, which will affect the telephone dialing and fax transmission and reception, especially when the ADSL broadband user dials the Internet, which is likely to cause frequent dropped calls. The following figure 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 by the 10kΩ current limiting resistor and the polarity is changed by 4 diodes (or rectifier bridge). When the telephone feed voltage is applied. When it is 36V, the measured working current is about 1.2mA, and the brightness is low. When the current limiting resistor is replaced by 5.6kΩ, the working current is increased to 2.1mA: the brightness is slightly increased.

Considering that the telephone line LED light has an adverse effect on the Internet, it can not be connected to the telephone line frequently. The author has also made some modifications to the lamp. The circuit schematic of the transformation is shown in the figure below, and the middle 6 LEDs are changed into Parallel, at the same time add a 3.6V mobile phone lithium-ion battery, usually use the built-in new lithium battery work, when the current limiting resistor is 5.6Ω, the working current is about 120mA, the brightness is more satisfactory. In case of emergency, the telephone extension interface illumination can still be used. The modified working current is about 4.6mA, and the brightness is fairly good.