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Light Emitting Diodes (LED) Circuits
LEDs:   #'s - B     C - G      H - L       M - P       Q - T     U - Z 
 

Last Updated: October 24, 2017 02:55 PM

Circuits Designed by Dave Johnson, P.E. :

 Ultra Low Current 3v LED Flasher #6This circuit takes advantage of a tiny LMC7215 low current draw voltage comparator from National Semiconductor and a super efficient green LED from King Bright.  The 3v powered circuit forms a classic pulse generator circuit, which drives the LED.  The pulse width is set at about 20ms, the pulse rate is about 0.5Hz and the peak LED current is only 100ua. . . Circuit by David Johnson P.E.-February, 2011

 Ultra Low Power LED FlasherThe efficiency of some newer LEDs is amazing.  Some of the latest green LEDs can launch blinding light with just one milliamp of current.  I take advantage of one of these newer devices in the circuit below.  The flashing circuit uses a classic multivibrator . . . Hobby Circuit designed by Dave Johnson P.E.-December, 2008

 Universal LED FlasherThis low power LED flasher circuit draws about 100ua from any DC power supply ranging from 3 volts to 24 volts.  The 1.0Hz 10ms LED pulsed current is held to a constant 10ma. . . Circuit by David A. Johnson P.E.-July, 2006

 Universal-3v-LED-FlasherThe circuit below will flash any LED color with fixed current pulses powered by a 3v battery.  It uses a charge pump approach, which routes a constant current pulse through the LED, regardless of the LED voltage requirement.  Using this approach, white and. . . Circuit by David Johnson P.E.-June, 2008

 Up/Down Ramping Light Pushbutton ControlThere are times when you want a lamp to gradually change from dark to light and from light to dark, with each push of a pushbutton switch.  The circuit below performs this control function using a flip/flop and a classic pulse width modulation or PWM. . . Circuit by David Johnson P.E.-March, 2009

 Version a of 1.5v LED FlasherTo squeeze even more energy from a alkaline battery cell, this circuit adds two transistors to a circuit similar to the above design to boost the efficiency.  A small 1.5 volt alkaline N cell should flash the LED for a full year.  It too uses a "charge pump" technique to provide a LED the needed voltage. . . Circuit by David A. Johnson P.E.-June, 2000

 Voltage Monitor for a 9v BatteryNine voltage batteries are used in a wide variety of electronic devices.  But, you often donít know when it is time to change the battery until the device stops operating.  The hobby circuit below provides a visual indication when the battery needs to be . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

 Voltage to Frequency Converter + 1us LED Pulse DriverThis circuit receives the signal from the above amplifier and launches powerful 1uS infrared light pulses from a low cost LED that are frequency modulated by the audio information.  The 10KHz center frequency of the pulse stream is low enough so a standard. . . Circuit by Dave Johnson P.E.-March, 1999


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

Ultra Low Current 3v LED Flasher #6 -  This circuit takes advantage of a tiny LMC7215 low current draw voltage comparator from National Semiconductor and a super efficient green LED from King Bright.  The 3v powered circuit forms a classic pulse generator circuit, which drives the LED.  The pulse width is set at about 20ms, the pulse rate is about 0.5Hz and the peak LED current is only 100ua. . . Circuit by David Johnson P.E.-February, 2011

Ultra Low Power LED Flasher -  The efficiency of some newer LEDs is amazing.  Some of the latest green LEDs can launch blinding light with just one milliamp of current.  I take advantage of one of these newer devices in the circuit below.  The flashing circuit uses a classic multivibrator . . . Hobby Circuit designed by Dave Johnson P.E.-December, 2008

Ultra-Bright LED Lamp -  This ultra-bright white LED lamp works on 230V AC with minimal power consumption.  It can be used to illuminate VU meters, SWR meters, etc.  Ultra-bright LEDs available in the market cost...__ Electronics Projects for You

Ultra-Simple Circuit Voltage Probe -  Detects 1.8 to 230 Volts DC or AC Minimum parts counting.  Circuit diagram: Parts: D1 5 or 3mm.  Red LED D2 5 or 3mm.  Green or Yellow LED LP1 220V 6W Filament Lamp Bulb P1 Red Probe P2 Black Probe Device purpose: This circuit is not a novelty, but it __ Designed by Flavio Dellepiane

Universal Flasher -  LED flasher with the LM3909 IC and runs from1.5-Volt battery.   __ Designed by Tony van Roon  VA3AVR

Universal Input TRIAC Dimmable 14W LED Driver -  The LT3799 is an isolated flyback controller with power factor correction specifically designed for driving LEDs.  The controller operates using critical conduction mode allowing the use of a small transformer.  Using a novel current sensing scheme, the controller is able to deliver a well regulated current to the secondary side without using an opto-coupler.  A strong gate driver is included to drive an external high voltage MOSFET.  Utilizing an onboard multiplier, the LT3799 typically achieves power factors of 0.97.  __ Linear Technology/Analog Devices App Note, Jun 21, 2010

Universal LED Flasher -  This low power LED flasher circuit draws about 100ua from any DC power supply ranging from 3 volts to 24 volts.  The 1.0Hz 10ms LED pulsed current is held to a constant 10ma. . . Circuit by David A. Johnson P.E.-July, 2006

Universal-3v-LED-Flasher -  The circuit below will flash any LED color with fixed current pulses powered by a 3v battery.  It uses a charge pump approach, which routes a constant current pulse through the LED, regardless of the LED voltage requirement.  Using this approach, white and. . . Circuit by David Johnson P.E.-June, 2008

Up / Down Digital Counter with 7 Segment LED Displays -  REVISED   Really as Simple as you can get and has 4 Displays __ Designed by G.L. Chemelec

Up/Down Ramping Light Pushbutton Control -  There are times when you want a lamp to gradually change from dark to light and from light to dark, with each push of a pushbutton switch.  The circuit below performs this control function using a flip/flop and a classic pulse width modulation or PWM. . . Circuit by David Johnson P.E.-March, 2009

USB LED Light -  A simply and easy-to-make circuit, useful when working with the computer at night.   (6/08/2006)  __ Designed by Jose Pino

USB LED LoA - D -  The board supports driving two separate tri-color LEDs.  More can be setup inline if desired.  Currently the software only uses the second LED and its color represents the CPU load of the system in real-time.  Blue for idle and gradients light blue, green, yellow, orange, and finally red indicating heavy CPU utilization.  If the system fails to respond, the LED begins flashing RED to indicate a lack of communication from the software.  This lets you easily identify a crashed machine in a rack for example.  

USB LED Night Light -  A typical USB LED bulb shown in Fig.1 is a 5V, 5W USB-powered solid-state lamp.  At the heart of this light bulb is a circular aluminium PCB made with a...__ Electronics Projects for You

Use a CFL ballast to drive LEDs -  04/26/07  EDN-Design Ideas A CFL ballast can drive a string of as many as 64 LEDs __ Circuit Design by Christian Rausch, Unterhaching, Germany

Use an LED Matrix Horizontally -  02/16/12  EDN-Design Ideas Using one 5◊7 LED matrix horizontally instead of vertically allows the display of two characters instead of one.  LEDs provide a convenient way to electronically display information.  Although the seven-segment LED display, arranged in the form of the digit 8, is common, it does not allow the display of some alphanumeric characters.  A 5◊7 LED matrix allows the display of all ASCII characters, as well as graphics shapes.  LEDs provide a convenient way to electronically display information.  Although the seven-segment LED display, arranged in the form of the digit 8, is common, it does not allow the display of some alphanumeric characters.  A 5◊7 LED matrix allows the display of all ASCII characters, as well as graphics shapes.  The circuit in this Design Idea shows an unconventional way to use a 5◊7 LED matrix. 
 __ Circuit Design by Benabadji Noureddine

Use an LED to Sense & Emit Light -  14-May-09 EDN-Design Ideas LEDs in portable devices often show power status, battery status, or Bluetooth-connection activity.  LEDs can be major factors in determining battery life because their intensity is directly proportional to power drain __ Circuit Design by Rafael Camarota, Altera Corp, San Jose, CA

Use LEDs as Photodiodes -  11/18/10 EDN-Design Ideas Ambient light changes an LED's resistance, making it act like a photodiode.  [Design Idea   by Raju R Baddi, Raman Research Institute, Bangalore, India __ Circuit Design by Raju R Baddi, Raman Research Institute, Bangalore, India

Use Simple Circuit LED for near-IR light -  09/01/98 EDN-Design Ideas NOTE :  File has many circuits, scroll down.  You can successfully use LEDs as sources of near-infrared light.  However, when you need a source of light with precisely controlled power, a feedback loop is necessary to compensate for the temporal and thermal changes of the LED parameters.  Standard LED types come with neither these monitoring detectors nor an external monitoring photodiode to detect part of the emitted light and generate a feedback signal.  The situation calls for some mechanical fixture to mount the photodiode. __ Circuit Design by Lukasz Sliwczynski, Marcin Lipinski, Institute of Electronics, Krakow, Poland

Using the LM317T with LED Lighting -  Use an LM317T to regulate the current in LED lighting projects.   __ Designed by REUK-Renewable Energy UK website

Using the TPS61040 in High Voltage Applications -  TI App Note 

UV LED Flashlight Driver -  The rapid development of LED technology is also reflected in the production of integrated drivers, often called LED Drivers.  The market is plentiful lots of different integrated circuits for this purpose.  There are circuits for generating serial or parallel cascades LED Step-Up and Step-Down Convertor, charge pumps.  But when you need them to realize any involvement, and usually encounter unexpected problems.  Many drivers LED  (LED Drivers) is designed for a specific range of consumer electronics and often lacks the characteristics required of us. __ Designed by © Pavel Janko

Valentine Heart -  18 LEDs flash at three different rates and you can use these to create an eye-catching Valentine Heart for that special person! A template for the heart shape can be downloaded.  The circuit is kept simple  (and low cost) by using the 4060B IC which is a counter and oscillator  (clock) in one package.  The circuit requires a 9V supply, such as a PP3 battery __ Designed by John Hewes

Versatile LED Display -  This circuit uses an erasable programmable read-only memory  (EPROM) to display various light patterns on LEDs.  Since bicolour LEDs  (comprising green and red LEDs) have been used, display is possible in...__ Electronics Projects for You

Version a of 1.5v LED Flasher -  To squeeze even more energy from a alkaline battery cell, this circuit adds two transistors to a circuit similar to the above design to boost the efficiency.  A small 1.5 volt alkaline N cell should flash the LED for a full year.  It too uses a "charge pump" technique to provide a LED the needed voltage. . . Circuit by David A. Johnson P.E.-June, 2000

Video Design Idea: Buck regulator controls white LED with optical feedback -  10/25/07  EDN-Video Design IdeasBy using optical feedback, you can stabilize the output level of a high-intensity LED __ Circuit Design by Dhananjay V Gadre, Netaji Subhas Institute of Technology, New Delhi, India

Video Design Idea: LED senses & displays Ambient light intensity -  09/05/07  EDN-Video Design IdeasExplains how an LED can double as a photosensor and a visual indicator of ambient-light intensity __ Circuit Design by Dhananjay V Gadre of India's Netaji Subhas Institute of Technology

Voltage Monitor -  This voltage monitor circuit is based on an Elektor design with a 555 timer IC in the book 302 Circuits, which uses two LEDs  (red and green) to indicate whether the voltage is within range.  must register on this site __ Designed by Published in Elecktor July/Aug, 2013

Voltage Monitor -  When the input voltage is 0 the LED glows.  The LED stops glowing when the voltage rises to the level determined by R2.  Reverse + and, pins to reverse operating mode.  To set voltage at which LED goes  __ Contact: IQ Technologies

Voltage Monitor for a 9v Battery -  Nine voltage batteries are used in a wide variety of electronic devices.  But, you often donít know when it is time to change the battery until the device stops operating.  The hobby circuit below provides a visual indication when the battery needs to be . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

Voltage to Frequency Converter + 1us LED Pulse Driver -  This circuit receives the signal from the above amplifier and launches powerful 1uS infrared light pulses from a low cost LED that are frequency modulated by the audio information.  The 10KHz center frequency of the pulse stream is low enough so a standard. . . Circuit by Dave Johnson P.E.-March, 1999

Voltage-to-current converter drives white LEDs -  06/27/02 EDN-Design Ideas Reset generator uses "fleapower" = You sometimes need to drive a white LED from one 1.5V battery.  Unfortunately, the forward voltage of a white LED is 3 to 4V.  So, you would need a DC/DC converter to drive the LED from one battery.  Using the simple circuit in Figure 1, you can drive one white LED or two series-connected green LEDs, using only a few components __ Circuit Design by Susanne Nell, Breitenfurt, Austria

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LEDs:   #'s - B     C - G      H - L       M - P       Q - T     U - Z 

 


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