Simple and easy to make energy-saving LED flashlight

Flashlight batteries are not durable, and they need to be replaced after a short time, which will bring great trouble. Recently, a small flashlight was modified into an energy-saving LED flashlight, which solved this problem. Because a special LED driver integrated circuit is used, the original small flashlight can be slightly modified. It saves electricity, is easy to use, and has a long life of light-emitting components. As long as it is used correctly, the light-emitting diode does not need to be replaced for a long time.

How it works

AMC7135 is a 350mA ultra-low voltage dropout current regulator. AMC7135 can drive 1~3W high-power LEDs with 350mA constant current output to achieve stable brightness and increase the total output power of the battery. Its ultra-low voltage dropout and low quiescent current characteristics extend the battery working time. No external components are required, and it has output short circuit/open circuit protection and built-in overheat protection device.

High-brightness white light-emitting diodes are new energy-saving lamps based on the semiconductor material gallium nitride. Their luminous intensity is 4 to 6 times that of fluorescent lamps and 15 to 30 times that of incandescent lamps. They can be used continuously for 100,000 hours, and their lifespan is about 100 times longer than that of ordinary incandescent bulbs. The working voltage of white light-emitting diodes is higher than that of other color light-emitting diodes, generally 2.5~3.5V. When the light-emitting diode starts working, as the current increases, the brightness of the light-emitting tube also increases. When the current reaches 10mA, the brightness does not change much, but the brightness of the surrounding darker areas increases more. Therefore, the working current is determined to be around 10~30mA. The working principle diagram is shown in the attached figure.

Component Selection

When purchasing LEDs, be sure to ask about the actual working voltage and current of the LED, and observe whether the white light emitted from the top of the LED is bright under the specified voltage and current. Some LED parameters are very discrete, such as its forward and reverse resistance has a large deviation in the LED current value under the standard voltage. If you want to use it because it is cheap, it is best to measure its actual working voltage and actual working current value.

Production and debugging

Since there is only one AMC7135 integrated block, no circuit board is used here. Instead, the components and wires are directly soldered and fixed in the flashlight with wax. The specific method is: after the components are soldered correctly, find a small flashlight (must have a larger head), solder the original glass bulb of the small electric bead with an electric soldering iron, and solder the light-emitting tube to the small electric bead holder. Install the prepared circuit on the head of the flashlight, and the light-emitting diode flashlight is made. It should be noted that the battery should be removed when the flashlight is not used for a long time to prevent battery leakage from corroding the flashlight and causing malfunctions.

This circuit is very simple and does not require any adjustment. It can be used after modification.