Power LED Driver Circuit. Circuit parts refer to the schematic diagram. R1 approximately 1. Yageo CFR 2. 5JB series. R3 current set resistor see below. Q1 small NPN transistor Fairchild 2. N5. 08. 8BU. Q2 large N channel FET Fairchild FQP5. N0. 6L. LED power LED Luxeon 1 watt white star LXHL MWEC. Power Led Driver Circuit Diagram' title='Power Led Driver Circuit Diagram' />In electronics, an LED circuit or LED driver is an electrical circuit used to power a lightemitting diode LED. The circuit must provide sufficient current to light. Semiconductor Components Industries, LLC, 2012 September, 2012 Rev. Publication Order Number NCL30000D NCL30000 Power Factor Corrected Dimmable LED Driver. LED Knight Rider Running Light Circuit Diagram In this 4017 Knight Rider circuit, the 555 is wired as an oscillator. It can be adjusted to give the. LED Cube driver project. Circuit Description. The LED cube is made up from 125 LEDs arranged into 5 layers of 25 LEDs each. This simple LED driver circuit can be used to drive many types of high power LEDs of different watts. The circuit is using LM317T voltage regulator. LgDBS.png' alt='Power Led Driver Circuit Diagram' title='Power Led Driver Circuit Diagram' />I used an old wall wart transformer, or you could use batteries. LED anything between 4 and 6 volts with enough current will be fine. A LED current. for more current you need to put the LED and Q2 on a heatsink see my notes in other power led instructables ive done. The circuit is a constant current source, the value of R3 sets the current. LED current is set by R3, it is approximately equal to 0. R3. R3 power the power dissipated by the resistor is approximately 0. R3. I set the LED current to 2. A by using R3 of 2. R3 power is 0. 1 watt, so a standard 14 watt resistor is fine. Here ill explain how the circuit works, and what the maximum limits are, you can skip this if you want. Specifications. input voltage 2. V to 1. 8V. output voltage up to 0. V less than the input voltage 0. V dropout. current 2. Maximum limits. the only real limit to the current source is Q2, and the power source used. Q2 acts as a variable resistor, stepping down the voltage from the power supply to match the need of the LEDs. Q2 will need a heatsink if there is a high LED current or if the power source voltage is a lot higher than the LED string voltage. LOT of power. The Q2 transistor specified will work up to about 1. V power supply. If you want more, look at my Instructable on LED circuits to see how the circuit needs to change. With no heat sinks at all, Q2 can only dissipate about 12 watt before getting really hot thats enough for a 2. A current with up to 3 volt difference between power supply and LED. Circuit function. Q2 is used as a variable resistor. Q2 starts out turned on by R1. Q1 is used as an over current sensing switch, and R3 is the sense resistor or set resistor that triggers Q1 when too much current is flowing. The main current flow is through the LEDs, through Q2, and through R3. When too much current flows through R3, Q1 will start to turn on, which starts turning off Q2. Turning off Q2 reduces the current through the LEDs and R3. So weve created a feedback loop, which continuously tracks the current and keeps it exactly at the set point at all times. This circuit is so simple, im going to build it without a circuit board. Q1 and Q2. laying the parts in front of you with the labels up and the pins down, pin 1 is on the left and pin 3 is on the right. LED negative to pin 2 of Q2. Now well start connecting Q1. Q1 upside down to the front of Q2 so that it is easier to work with. Q2 gets very hot, it will cause Q1 to reduce the current limit a safety feature Q1 to pin 1 of Q2. Q1 to pin 3 of Q2. R1 to that dangling LED plus wire. R1 to pin 1 of Q2. LED plus wire. it probably would have been easier to do that first actually. R3 to the side of Q2 so it stays in place. R3 to pin 3 of Q2. R3 to pin 1 of Q1. Q1. youre done well make it less flimsy in the next step. BLOB TRONICS. it doent look like much, but it works really well and is cheap and easy. Free Download Adobe Acrobat Reader For Windows Vista there. Capital US 1. 00.