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Power LEDs have changed the world of illumination. The number of experimentation on the ouput of power LEDs is the highest in the electronic hobby world. Before going through the intricacies of the luminance of power LEDs we must first know the characteristics of LEDs. A white LED is generally biased at a voltage range of 2.5 to 3.5V DC. Depending on the wattage of LED, the input current is determined. White LEDs are used for illumination purposes and are available right from 0.1Watt to 3Watts in general, with the same voltage characteristic but different current rating. Though very simplistic, it is interesting to use the following serially connected white LEDs in a chain. Here in this circuit 25 LEDs in a series have been considered a safe zone operation. We decide the bias voltage to be 3V DC in each of this rung. The total potential required to bias the LEDs is 25x3= 75V DC. A bridge rectifier is employed to rectify 120V AC line without any filter circuit being employe...

This is a Step-Up Booster Powers Eight White LEDs Project . Simal white LEDs are capable of delivering ample white light without the fragility problems and costs associated with fluorescent backlights. They do pose a problem however in that their forward voltage can be as high as 4 V, precluding them being from powered directly from a single Li-Ion cell. Applications requiring more white LEDs or higher efficiency can use an LT1615 boost converter to drive a series connected array of LEDs . The high efficiency circuit (about 80%) shown here can provide a constant-current drive for up to eight LEDs . Driving eight white LEDs in series requires at least 29 V at the output and this is possible thanks to the internal 36-V, 350-mA switch in the LT1615. The constant-current design of the circuit guarantees a steady current through all LEDs , regardless of the forward voltage differences between them. Although this circuit was designed to operate from a single Li-Ion battery (2.5V to 4.5V), ...

This is a generator circuit which is very useful, it simultaneously generates two types of noise, pink and white. The noise generator is a circuit that produces electrical noise . Noise generators are used to test , measure noise , frequency response , and other parameters . The circuit described here is based on the operational amplifier 741 .  Dual White Noise and Pink Noise Generator Circuit Diagram

This circuit will be used for a toy automotive to follow a white line. The motor is either a 3v sort with gearing to steer the automotive or a rotary actuator or a servo motor.When equal lightweight is detected by the photo resistors the voltage on the base of the primary transistor are mid rail and the circuit is adjusted via the 2k2 pot that the motor doesn't receive any voltage. When one in all the LDR's receives a lot of (or less) lightweight, the motor is activated. and also the same thing happens when the other LDR receives less or more light.

LOW NOISE WHITE LED DRIVER SYSTEM ELECTRONIC DIAGRAM The LM3570 evaluation board has a chip enable pin (active high logic) as well as a PWM (active high logic) pin which allows current sources to be turned on and off without completely disabling the part..The LM3570 is capable of supplying up to 80mA of current split between the regulated current sources and VOUT. The LM3570 comes in National’s LLP-14 package.