LED Light Emitting Diode Electronic Circuits, page 2

LED (Light Emitting Diodes) Circuits Page 2
LED: # A B C D - E F - H I - K L M - O P- R S T U - Z
Last Updated on: Friday, October 16, 2009 03:42 AM

Circuits Designed by Dave Johnson, P.E. :

AC Powered White LED Strings
A while back a guy by the name of Ken Schultz sent me a simple drawing of how he connected a string of 30 LEDs, to make a nice under the counter accent light, powered by 120vac. He wired the strings in two series sections of 15 LED each, but wired in opposite directions. He then used just one capacitor to limit the AC current through the two stings. I looked at the circuit and decided that it seemed quite reasonable. The only change I decided to make was to add a metal oxide resistor in series with the capacitor, to act as fuse and to limit the peak current, should there be a voltage spike on the AC line. With the two strings of 15, the current is first pumped through one series string, then as the AC line polarity changes, it flows through the second string. ...

AC Line Powered LED Pilot Light
This simple circuit can be used to light a LED indicator lamp, powered from the 120vac line. I have included component values for 240vac lines as well. (added 7/06)

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

A Clock Design using the PIC16c54 for LED Displays & Switch Inputs - Microchip Application Note Published 26-Aug-97 (app note added 6/06)

A low power, long life LED flashlight circuit - Scouring the Internet for information on LEDs, I accidentally stumbled upon a PDF detailing a flashlight made from PVC. For the torch, he biases ultra-bright LEDs with ballast resistors as described in my LED lighting guide. This is a simple solution, but a with a slightly more complicated circuit we can extend battery life by over ten times!...(project added 6/07)

A Step-Down Conversion Concept for a PWM-Mode Boost Converter - TI Application Note (added 2/06)

AC LEDs - Some useful Circuits with LEDs using the AC voltage. (5/28/2006)

Ac Line Powered LED Pilot Light - This simple circuit can be used to light a LED indicator lamp, powered from the 120vac line. I have included component values for 240vac lines as well. (added 7/06) ….(designed by David A. Johnson)

AC Line Powered LED Strings - This shows 4 different ways to string white LEDs that are powered by a 120vac or 240vac power line. The circuit was designed by Ken Schultz. (added 12/04) ….(designed by David A. Johnson)

AC Line Powered LEDs - The circuit above illustrates powering a LED (or two) from the 120 volt AC line using a capacitor to drop the voltage and a small resistor to limit the inrush current. Since the capacitor must pass current in both directions, a small diode is connected in parallel with the LED to provide a path for the negative half cycle...(circuit added 06/07/08)

Add Switch & LED I/O to DSP's Serial Port - 05/07/98 EDN-Design Ideas: NOTE: Page includes several designs, scroll to find this one....The circuit in Figure 1 monitors battery voltages from 2.7 to 5.5V while drawing less than 25 m A. When the voltage reaches a minimum threshold established by R1 and R2, (VTH=2.63V for the values shown), the high-side.....(design idea added 11/05)

Adjustable flashing LED - Use a 555 timer IC as the ASCII format (resistor controlled) frequency source, choose component values to run at 2 x desired flash rate, get the data sheet for this part, it's pretty comprehensive. Use the output to clock a flip flop ASCII format (e.g. 74HC74). Feed flip-flop Q and /Q outputs to simple transistor stages, viz... ASCII format (circuit added 05/06/07)

Air display - A Noisemaker without noise. A simple rotating display. Just spin and enjoy. While the "Air display" is rotating, it writes the message on the air. Because the "persistence of the vision", you will be able to read the message. Circuit, see JP6293E.gif. Download the HEX file, Program the PIC with JP6293E.hex. Algorithm, Build your own Air Display using code.txt....(electronic design added 06/07/08)

Alphanumeric LED Display Project - A phenomenal 256-diode ROM acts as a character generator for a two-digit hexadecimal display. (project added 11/06)

Alternating LED Blinker uses Four Parts - 03/26/98 EDN-Design Ideas: (design idea added 6/03) /Grand Prize Winner98

Alternating LED Flasher uses Minimal Parts - 11/20/97 EDN-Design Ideas: -A pair of alternating flashing LEDs makes an excellent visual alarm, this alternating LED flasher is based on one LED with built-in flashing function and two transistors driving or normal LED.....(design idea added 6/03)

Alternating LEDs Flasher - Classic astable multivibrator using 2 transistors. Transistor is not critical. Try these: 2N4401, 2N2222, NTE123A, NTE123AP, NTE159, TUP/TUN and those in your junk box, you may find that most of them will work....(Tony van Roon's electronic schematic / circuit added 4/02)

AN 30 LX1995 LED Driver: Camera Flash Application - Application Note Microsemi 1313 (added 05/07)

An Efficient & Low Cost Alternative to LEDs for Backlighting Handheld Computer Displays - DN1004 Design Notes (Linear Technology) (app note added 1/06)

An LED Flasher with a Slow Rise & Fall Time - A Simple Circuit Using a 555....(design added 12/08)

AN-1250: Inductive Based Switching Regulator Circuits Provide High Efficiency White LED Drives - National Semiconductor Application Note (app note added 2/06)

AN-1251: Switched Capacitor Circuits Provide Efficient & Functional White LED Drive - National Semiconductor Application Note (app note added 2/06)

AN-1291:Driving RGB LEDs using Lp3933 Lighting Management System - National Semiconductor Application Note (app note added 2/06)

AN-1293: Driving RGB LED using Lp3936 Lighting Management System - National Semiconductor Application Note (app note added 2/06)

AN-1324: LM3570: Low Noise White LED Driver System - National Semiconductor Application Note (app note added 2/06)

AN-1362: LM27961-Dual-Display White LED Driver with 3/2x Switched Capacitor Boost - National Semiconductor Application Note (app note added 2/06)

AN-1392:LM3485 LED Demo Board - National Semiconductor Application Note (app note added 2/06)

AN33 ZXSC100 Single cell DC-DC converter LED driving applications - Zetec Semiconductors Applications Notes ZXSC100 single cell DC-DC converter offers an ideal solution to driving white LEDs in flashlights, enabling operation from a single NiCd or NiMH cell. (app note added 6/06)

AN-347: Shielding & Guarding - AN-347 Analog Devices Application Note (app note added 2/06) How to Exclude Interference-Type Noise. What to do and Why to do it-A Rational Approach

AN529: Multiplexing LED Drive & 4x4 Keypad Sampling - Microchip Application Note Published 26-Aug-97 (app note added 2/06)

AN590: A Clock Design using the PIC16c54 for LED Displays & Switch Inputs - Microchip Application Note Published 26-Aug-97 (app note added 6/06)

AN-772: A Design & Manufacturing Guide for the Lead Frame Chip Scale Package - AN-772 Analog Devices Application Note (app note added 2/06)

AN874: Buck Configuration High-Power LED Driver - Microchip Application Note Published 4-Jan-06 (app note added 2/06)

AN948: Efficiently Powering Nine White LEDs with the MCP1650 - Microchip Application Note Published 3-Aug-04 (app note added 2/06)

Analog LED Bar VU Meter - The circuit was designed to work with an audio power amplifier which operated off +18v-0v-18v power rails. The actual voltage used is not too critical except that the feedback is referred to the LED chain which itself is anchored to a +12v rail, hence the separate stabilizer .... (added 5/09)

Analyze LED characteristics with PSPICE - 01/18/01 EDN-Design Ideas: Recent advances in LED technology have lead to LEDs' widespread use in outdoor-signal applications, such as in traffic and railroad signals. A typical LED signal consists of an LED array and a power supply. When a low-voltage power supply is eir desirable or mandatory, series/parallel combinations of LEDs become inevitable. However, analyzing and optimizing series/parallel combinations of LEDs with varying forward characteristics can be complicated. Using parametric and Monte Carlo capabilities of PSpice greatly simplifies this task.....(design idea added 8/03)

AN-H48: Buck-Based LED Drivers using the HV9910 - Supertex Semiconductors (app note added 2/06)

AN-H50: Constant Off-Time Buck-Based LED Drivers using HV9910 - Supertex Semiconductors (app note added 2/06)

AN-H51: Buck/Boost-Based LED Drivers using the HV9910 - Supertex Semiconductors (app note added 2/06)

AN-H52: HV9931 Unity Power Factor LED Driver - Supertex Semiconductors (app note added 2/06)

Animated LED Signboard PIC16C84 - (electronic circuit added 4/05)

Anti-Flicker Circuit for LED Christmas Lights - I like the idea of LED light strings that rarely need new bulbs but the flicker drives me crazy! Here's the solution for single strings of LEDs all in series (circuit added 08/08/08)

Assorted LED circuits - (schematic added 03/04/05)

Astable multivibrator (blinkie) - A pulse generator, or astable, circuit can be made using four resistors, two capacitors, two LEDs and two transistors. 'Blinkie' uses these components to form a face, with the flashing LEDs representing the eyes. (electronic design added 08/08/08

Astable multivibrator lights LED from a single cell - 08/21/08 EDN-Design Ideas: A classical multivibrator drives a step-up inductor to power an LED from a single cell.....(design idea added 09/08)

AT89C2051 Serial Coms to LED Driver - (circuit / schematic design added 6/06)

AT89C2051/4051 Driving Dot Led - (circuit added 7/02)

Audio LED VU Meter - The circuit was designed to work with an audio power amplifier which operated off +18v-0v-18v power rails. The actual voltage used is not too critical except that the feedback is referred to the LED chain which itself is anchored to a +12v rail, hence the separate stabilizer .... (added 5/09)

Audio Light Modulator - Audio light modulations add to enjoyment of music during functions organised at home or outdoors. Presented here is one such simple circuit in which light is modulated using a small fraction of audio output from speaker terminals of audio amplifier. The output from speaker terminals of audio amplifier is connected to a transformer.... (added 10/05)

Automatic Dual Output Display - This circuit lights up ten bulbs sequentially, first in one direction and n in opposite direction, thus presenting a nice visual effect. In this circuit, gates N1 and N2 form an oscillator. The output of this oscillator is used as a clock for BCD up/down counter CD4510 (IC2). Depending on logic state at its pin 10, counter counts up or down. During count up operation, pin 7 of IC2 outputs an active low pulse on reaching ninth count. Similarly, during count-down operation, you again.... (added 10/05)

Automatic Room Lights - An ordinary automatic room power control circuit has only one light sensor. So when a person enters room it gets one pulse and lights come ‘on.’ When person goes out it gets anor pulse and lights go ‘off.’ But what happens when two persons enter room, one after or? It gets two pulses and lights remain in ‘off’ .... (added 10/05)

AVR Dotmatrix - avrDotmatrix, Is a 5x7 LED Matrix Display controlled by a ATMega8 to display scrolling text, time or temperatures. The pattern is generated with multiplexing the 5 matrix columns and setting the correct row bits. This projects is still in development and i'm gonna add a temperature sensor (LM75)...(circuit added 02/09)

LED: # A B C D - E F - H I - K L M - O P- R S T U - Z