LED Light Emitting Diode Electronic Circuits, page 10

LED (Light Emitting Diodes) Circuits Page 10
LED: # A B C D - E F - H I - K L M - O P- R S T U - Z
Last Updated on: Friday, March 12, 2010 12:07 PM

Circuits Designed by Dave Johnson, P.E. :

Reduced Power Sequential LED Flasher
The 74HC4017 is a neat decade counter which has 10 decoded outputs. When supplied with a low frequency clock and with a LED attached to each of the outputs, an interesting ten step sequential flasher effect can be produced. The LEDs can be configured in a wide variety of patterns of loops, lines or arrows. But, these circuits can often be power hogs. To reduce the average current needed to produce the same effect, you can strobe the individual LEDs with a short 10mS pulse.

Remote LED Indicator Light -- NEW
There are times when you would like to transmit a signal from one LED indicator light to second LED at another location. The circuit below works well for this application. It takes advantage of the fact that the internal infrared LED inside an opto-isolator has a lower voltage drop than the visible LED being tapped into. Using a darlington type opto-isolator also means very little current needs to be diverted to the isolator.....

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

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)

Photo Sensor Circuit - Here's a circuit that takes advantage of the photo-voltaic voltage of an ordinary LED. The LED voltage is buffered by a junction FET transistor and then applied to the inverting input of an op-amp with a gain of about 20. This produces a change of about 5 volts at the output from darkness to bright light. The 100K potentiometer can be set so that the output is around 7 volts in darkness and falls to about 2 volts in bright light... (added 4/05)

Photovoltaic Switch disables unused LEDs - 03/18/04 EDN-Design Ideas: In many applications, it's desirable to disable LEDs used for system verification. Many options are available for the disabling function, including manual SPST (single-pole single-throw)switches, enhancementand depletion-mode MOSFETs, bipolar-junction transistors, and JFETs.....(design idea added 1/05)

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

PIC Digital Timer (4 timed outputs) - This circuit uses the PIC16F628 microcontroller to provide 4 timed outputs that can be programmed from 1 minute to 1 week. An extra 8 bit shift register (74HC164) is used for the 4 timer outputs and to display four additional indicator lights….(electronic circuit added 05/09)

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

PIC microprocessor drives 20 LED dot or bar graph display - 09/01/06 EDN-Design Ideas: Indicator circuit features low cost and minimal component count.....(design idea added 05/06/07)

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

PIC16F84 LED Chaser (ke4nyv) - (electronic circuit added 7/03)

PIC16F84 LED Signboard (Seiichi Inoue) - (circuit / schematic design added 6/06)

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

Picxie 2 8x8 Animated LED Signboard - The firmware supplied in current sourcecode archive is VERY BASIC. I do intend to draw more patterns. However, a vast workload coupled with possible emigration has put finished firmware on hold. Please do go ahead and build this circuit though supplied firmware is fully functional. You can have hours of fun designing your own patterns and effects! Uses PIC16F84. (schematic / circuit added 10/02)

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

Pong in a 3D LED matrix - If you have ever wanted to play pong on a three dimensional display, then this one is for you. There are 1,000 white LEDs in the matrix that can refresh at a rate of 60 fps….(project added 6/07)

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: Bright LEDs are becoming prominent sources of light. They often have better efficiency and reliability than.....(design idea added 1/05)

Powering LEDs costs mere pennies 33 - Lately the hoopla concerning LED lighting has been overwhelming. Everyone claims this costs mere pennies to power. I decided to put a new twist on a classic science experiment to prove that LEDs do cost pennies to power. Literally….(project added 6/07)

Powers LED with Constant Current Starting at 100MV over VF - This is a proof of concept circuit which needs improvement. The part values shown will run a high efficiency red LED with a Vf of 1.9V from only 2 nicads, right down to 2 volts. For a white LED you will need more batteries and you must increase the 1.0K resistor to a higher value. Current sensing at a .... (added 2/05)

Processor's PWM output Controls LCD/LED Driver - 05/27/04 EDN-Design Ideas: 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,.....(design idea added 1/05)

Programmable LED Flashers - LED goes to steady state after a preset number of flashes. Two simple, wide supply range operating circuits. (schematic added 6/07)

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

Propellor clock PIC16F84 - a few light emitting diodes spin, precisely controlled by a PIC microprocessor, giving the illusion of a larger array. (added 7/03)

Pulsed LED Test Circuit - This circuit is designed to test visible and infrared LEDs in pulsed mode operations. It can drive the LED with peak currents in excess of 10 amps. A light detector nearby can monitor the response time and intensity of the LED under test. ….(designed by David A. Johnson)

Pulsed LEDA High Current Circuit. - Just to Play withBut it Might have some Practical Applications....(circuit design added 12/08)

PWM Controller Drives LEDs from High Voltage Lines - 03/04/04 EDN-Design Ideas: 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.....(design idea added1/05)

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)

Quiz - This project can be used for a quiz with up to 4 contestants (or teams). Each contestant has a trigger push-switch and LED. When a trigger switch is pressed it lights the corresponding LED, sounds the bleeper and prevents the other trigger switches from working, therefore showing which contestant ....Designed by John Hewes (circuit added 06/07/08)

Rainbow LED indicates voltage With color - 12/07/04 EDN-Design Ideas: …..(design idea added 1/05)

Ramping LED Driver - The circuit below was designed to drive a LED with an intensity ramping mode. Two 555 timers generate two different triangle waveforms. The upper device generates a 10KHz signal while the lower unit produces a 1Hz signal. The two signals are fed to a voltage comparator. The result is a pulse width modulation (PWM) signal, which with the aid of the FET, drives the LED in such a way that its average light output slowly ramps from about zero light to maximum and then slowly dims back down. The circuit should operate over a supply voltage ranging from 3v to 12v. You can easily vary the ramping time by changing the value of the 1M resistor. For an interesting effect, you can place a 1N4148 diode in parallel with the 1M resistor, with the cathode (banded end) side connected to pin 3. ….(designed by David A. Johnson)

Random Flasher for 8 LEDs Project - This project flashes eight LEDs in an apparently random manner. It uses a 4026 combined counter and display driver IC which is designed for driving 7-segment LED displays. The sequence is not really random because seven of the LEDs would normally be the display segments, the eighth LED is driven by an output that is normally ....(circuit added 06/07/08)

Red LEDs function as light sensors - 03/20/08 EDN-Design Ideas: You can build simple LED illuminators using the red LED to sense ambient-light level.....(design idea added 03/08)

Reduced Power Sequential LED Flasher - The 74HC4017 is a neat decade counter which has 10 decoded outputs. When supplied with a low frequency clock and with a LED attached to each of the outputs, an interesting ten step sequential flasher effect can be produced. The LEDs can be configured in a wide variety of patterns of loops, lines or arrows. But, these circuits can often be power hogs. To reduce the average current needed to produce the same effect, you can strobe the individual LEDs with a short 10mS pulse. ….(designed by David A. Johnson)

Remote LED Indicator Light - There are times when you would like to transmit a signal from one LED indicator light to second LED at another location. The circuit below works well for this application. It takes advantage of the fact that the internal infrared LED inside an opto-isolator has a lower voltage drop than the visible LED being tapped into. Using a darlington type opto-isolator also means very little current needs to be diverted to the isolator..... ….(designed by David A. Johnson)

Remote Solar LED light - (electronic diagram added 6/03)

Reset Circuit Provides Snappy Action - 04/29/99 EDN-Design Ideas: 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,.....(design idea added 11/05)

RGB LED colour wash light - This PIC based circuit uses Red, Green and Blue high brightness LEDs that are pulse width modulated (PWM) to vary the intensity of each colour LED. This allows effectively any colour to be generated. The circuit is designed to fit into a low voltage Halogen light fitting. A look up table is used to program .... (added 6/06)

Robot Beacon - One of the biggest hurdles to overcome is the "image" of the PIC12C508A chip. We tend to think of it as a single chip, just like any other 8-pin chip. But it's not. It's really equivalent to 5, 6, 8 or even more chips in a single package! And each chip can be programmed to do almost exactly what you want!....(circuit design added 04/09)

Robot beacon light display for mounting on top of a robot - (diagram added 05/07)

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

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

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