LED (Light Emitting Diodes) Circuits   Page 10
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Last Updated on: Friday, July 18, 2008 11:33 AM
 

Parallel White LED Driver:  National Semiconductor Application Note LM3595 August 2003 (app note added 02/05)

Park Aid:  3-LEDs signal bumper-barrier distance Infrared operation, indoor use (added 9/04)

PIC Digital Clock Timer:  (electronic (schematic / circuit added 11/05)

PIC Micro LED Projects:  (electronic circuit added 7/03)

PIC16F84 LED Chaser #2:  (electronic circuit added 7/03)

PIC16F84 LED Chaser:  (circuit / schematic design added 6/06)

PIC16F84 LED Signboard #2:  (circuit / schematic design added 6/06)

PIC16F84 LED Signboard:  (circuit / schematic design added 6/06)

Picxie 2 8x8 Animated LED Signboard:  (schematic / circuit added 10/02)

Pocket LED Light:  An LED pocket light operates with only one cell of battery.  (added 10/05)

Power Booster for the MLX90121:  Melexis Application Note  (app note added 2/06)

Power Ok LED for PC:  Electronic Design 1/14/98 Simple, low cost three transistor circuit lights LED only if all four PC power supply voltages (+/-5V, +/-12V) are present. (added 9/04)

Power Supply IC Drives Multiple LEDs:  09/02/04 EDN Design Ideas  /  (added 1/05)  Bright LEDs are becoming prominent sources of light. They often have better efficiency and reliability than do conventional light sources. Although LEDs can operate from an energy source as simple as a battery and a resistor, driving a string of LEDs in constant-current mode can better match the luminance between the devices without needing to match LEDs for their forward-voltage drop....

Processor's PWM output Controls LCD/LED Driver:  05/27/04 EDN Design Ideas  /  (added 1/05)  The PWM (pulse-width-modulation) output available from many microprocessors is based on an internal 8or 16-bit counter and features a programmable duty cycle. It is suitable for adjusting the output of an LCD driver, a negative-voltage LCD driver, or a current-controlled LED driver. cost alternative that provides not only a 4to 20-mA output,

Progressive Field Increase for the MLX90121:  Melexis Application Note  (app note added 2/06)

Propeller a mechanically scanned LED clock :  (electronic Circuit / Schematic added 10/04)

Propeller Clock:  a few light emitting diodes spin, precisely controlled by a PIC microprocessor, giving the illusion of a larger array. (added 7/03)

PWM Controller Drives LEDs from High Voltage Lines:  03/04/04 EDN Design Ideas  / (added 11/05)  Powering LEDs from a wide dc range—say, 30 to 380V—without wasting a lot of power in the regulating block, is a difficult task when the LED current needs to be constant. Dedicated LED drivers are available, but they usually implement boost structures and are thus inadequate for high-voltage inputs.

PWM White LED Drivers:  (electronic circuit added 4/05)

Quad DC/DC Converter for Triple Output TFT Supply Plus LED Driver:  Linear Technology LT1942 (app note added 02/05)

Rainbow LED Indicates Voltage with Color:  12/07/04 EDN Design Ideas  / (added 1/05)  Meters that indicate analog levels via a moving-pointer meter, a numeric display, or a column of LEDs typically occupy considerable panel area and require more than a casual glance to read. An indicator lamp or LED takes little space but indicates only an on or off condition. However, an unobtrusive LED that changes color as a function of a measured value would enable an observer to easily asse...

Receiver Design Notes:  Melexis Application Note  (app note added 2/06)

Remote Solar LED Light:  (electronic diagram added 6/03)

Reset Circuit Provides Snappy Action:  04/29/99 EDN-Design Ideas / (added 11/05) The circuit in Figure 1 provides a 1-sec reset, using multiple AND gates for increased fanout. Intended for breadboarding or prototyping, the circuit generates a "snappy" master reset that remains active long enough to eliminate questionable start-ups. When you apply power to the circuit, the timing capacitor begins charging through the 1-Mwresistor, turning on the npn transistor. The AND-gate inputs go low, generating the reset signal and turning on the reset LED. When the timing capacitor brings the transistor's base nearer to ground, the transistor turns off, and the 2.2-kwresistor pulls the AND gates' inputs high. The transistor isolates the capacitor from the AND gates' internal pull-up resistors and provides a smooth transition through the logic threshold. Upon removal of power, the 1N4001 diode discharges the timing capacitor. (DI #2351).

Resistor Calculator :  Luxeon Application Note  (app note added 2/06)

Resistor Color Code Tutorial:  (electronic design / schematic added 2/06)

RF Antenna Basics :  Melexis Application Note  (app note added 2/06)

RR LED flasher (alternating) :  ASCII format (circuit design added 11/06)

Running Message Display:  (electronic circuit added 10/05)

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