A Torch Made of LED

Figure 1 

The circuit demonstrates a torch out of Light-Emitting Diode (LED).

LED’s are semiconductor diodes that are commonly electronic light source when electric current pass through them. Although they have a resistor in series to limit the current to a safer value, a large amount of current can destroy them easily. They are available in a wide variety of shapes and sizes. The typical LED has a round cross-section which are usually used because of ease of installation. They are also available in variety of colors such as red, green, yellow, orange and amber. White and blue are more expensive than the others. The colour is not determined by the enclosure but by the semiconductor material.

LED torches have several uses being a nigh light, tiny transforming terminator or a flashlight. Having a short life term of the bulb and battery is one common problem with an average consumption of 2W. But the circuit was designed to consume 24mW, giving the batteries longer life. The circuit being this simple can still shed a light on a darker pathway.

The circuit did not utilize an ordinary 555 timer due to its resistance value. Instead, it used a CMOS type 555 timer (7555) for low power consumption and high noise immunity. Using a white LED, the illumination can reach 30 meters. To focus the beam, short focal length convex lens is placed ahead of LED. For smoother beam, utilize another very short focal length lens. The corresponding values for resistor R3 would result to 9 V at 47 Ohms or 12 V at 560 Ohms if a different voltage supply is used.

LED torches have evolved from the past years placing itself on the cutting edge of technology. The technology of LED provides intense efficient illumination surpassing 10 times the conventional incandescent technology bulb. Unlike these bulbs which energy is mainly converted to heat, the LED has � of its energy converted to light. Among their other uses are remote control information transmitter, digital clock numbers or indicators in appliances.

Source:www.zen22142.zen.co.uk/Circuits/Misc/torch.htm