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LED (Light Emitting Diodes) Circuits   Page 1
LED:   #       A        B        C         D - E          F - H        I - K         
L         M - O         P- R         S         T        U - Z
Last Updated on: Saturday, April 26, 2008 07:05 AM
Circuits Designed by Dave Johnson, P.E. :
  • 0.5V Negative Supply
    Although not very efficient, this simple circuit, consisting of two LEDs and a photo diode, generates a negative voltage with a current level of a couple milliamps.  It is ideal for supplying a negative rail to low power “rail to rail” op amp circuits, which need to have a true zero volts output.
  • 1.5V LED Flasher VERSION A
    Many published circuits that Flash LEDs need 3 volts or more. This circuit uses only a single inexpensive C-MOS IC and Flashes the LED for a full year on a single 1.5 volt AA alkaline battery cell. The circuit uses a charge pump technique to provide the LED the needed voltage.
  • 1.5V LED Flasher VERSION B
    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.
  • 2 LINE TELEPHONE LINE STATUS INDICATOR
    Many home businesses use multiple phone lines. This circuit gives you a visual indication when a line is in operation. The two AA battery cells should provide enough power for about one year of operation. The circuit is line polarity insensitive.
  • 9v Battery Voltage Monitor
    This circuit turns on a LED whenever the voltage of a standard 9v battery connected to the circuit drops below 7.2 volts.  It uses a LTC1440 comparator, which also contains a 1.18v reference diode.  In standby mode, the circuit draws only 4uA. (added 7/06)
  • 40KHz TV-VCR LIGHT SOURCE REPEATER
    This circuit is designed to be placed directly in front of a standard TV or VCR remote. The exiting light pulses produced by the circuit match the pulses from the remote but are about 10 times more powerful. Using the device, the remote can operate a TV or VCR over three times the normal distance.
Links to electronic schematics, circuits, designs and/or diagrams for engineers, hobbyists, students & inventors
(AN 30) LX1995 LED Driver: Camera Flash Application: Application Note Microsemi 1313 (added 05/07)

µP Displays 10 Bit Data on Three LEDs:  11/07/96 EDN-Design Ideas / (added 6/06)  circuit in Figure 1 uses a PIC16C55 µP to read 10-bit binary data and directly display  data in decimal format on three common-cathode LED displays. If value of  data exceeds 999,  displays show three hyphens (---) to represent overflow.  PIC16C55 has high drive capability. Each output pin can source 20 mA and sink 25 mA;  outputs can thus directly drive  LED display

0.6/1.6 MHz Boost Converters with 22V Inrternal FET Wsitch in SOT-32:  National Semiconductor Application Note LM2731 July 2003 (app note added 02/05)

1 Watt 5 Volts Power Booster for the MLX90121:  Melexis Application Note  (app note added 2/06)

1.2MHz/2.4MHz White LED Step-Up Converters with Built-In Schottky in ThinSOT:  Linear Technology LT3465 (app note added 6/06)

1.5 Volt LED Flashers #1:  four circuits with description (added 4/02)

1.5V Battery Powers White LED Driver:  09/30/04 EDN Design Ideas  / (added 1/06)  Although white LEDs are common in a variety of lighting applications, ir 3 to 4V forward-voltage drop makes low-voltage applications challenging. Charge pumps and or ICs are available for driving white LEDs, but y generally don't work with  low supply voltage of 1.5V in single-cell-battery applications.

1.5V LED Flasher Oscillator:  Mimics  now discontinued LM3909 IC Can be adapted to a wide variety of applications (added 9/04)

10 Channel LED Sequencer:  based on4017 (added 4/02)

10 LED Sequencer:  in PDF format, text in Finnish (added 4/02)
10, 8 And 6 Step LED Circuits (CD4017):(electronic circuit added 05/07)

100ma UltraLow Noise Charge Pump LED Supply with Output Current Adjust:  Linear Technology LTC3201 (app note added 02/05)

12 Volt Lamp Fader (LEDs or Incandescent):  (electronic circuit added 10/05)

13 Color LED Rainbow:  Only a few years ago,  choice of LEDs was limited to IR, red, yellow, and green.  LED manufacturers have been busy extending  spectrum, and filling in  gaps.  latest generation of organic LEDs (OLEDs) has added some dazzling new colors to  spectrum. This circuit uses a set of 13 differently colored LEDs to generate a full color spectrum.  photo does not fully represent  colors generated due to camera limitations.  real-world display is very eye-catching. If you want to "trick out" your PC, this circuit is for you. Forget about those boring blue PC light displays.  (added 10/05)

13.56MHz RFID Systems and Antennas Design Guide:  Melexis Application Note  (app note added 2/06)

15V Battery Powers White LED Driver:  09/30/04 EDN Design Ideas  /  (added 1/05)  Although white LEDs are common in a variety of lighting applications, ir 3 to 4V forward-voltage drop makes low-voltage applications challenging. Charge pumps and or ICs are available for driving white LEDs, but y generally don't work with  low supply voltage of 1.5V in single-cell-battery applications....

16 Stage Bidirectional LED Sequencer:  (circuit added 7/02)

16x16 LED Matrix and Driver:  (circuit added 9/04)

18 Stage LED Sequencer:  (electronic (schematic / circuit added 11/05)

1a Flash LED Driver :  Sipex Application Note  (app note added 2/06)

1a Low Noise High Current LED Charge Pump with Independent Torch/Flash Current Control:  Linear Technology LT3216 (app note added 02/05)

2 LED Flasher:  simple2transistor circuit which blinks2LEDs (added 4/02)

2 Transistor 2 LED Flasher:  (circuit / schematic design added 6/06)

2 Transistor LED Flasher #1:  (circuit added 7/02)

2 Transistor LED Flasher #2:  (circuit / schematic design added 6/06)

20ma LED Ballast:  I use this circuit for general use to power white LEDs, like a headset light I use on my desk and a keyboard light for my computer. I built it into a tiny Radio Shack project box (270-288), which y no longer sell. I put heat-shrink tubing around  female output connector (RS P/N 273-1743), so that  contacts are not exposed, but you can still plug and unplug it. Designed by Andrew R. Morris  (added 9/05)

27MHz to 67MHz Low-RF Single-Conversion Superhet Receiver:  Melexis Application Note  (app note added 2/06)

28 LED Clock Timer 72 LED Clock:  programmable clock Timer circuit that uses individual LEDs to indicate hours and minutes (added 4/02)

3-Colour Display using Bicolour LEDs:  (electronic Circuit / Schematic added 10/04)

40 LED Bicycle Light (555 Timer 6 Volt):  (circuit added 7/02)
5x7 Display: (electronic circuit added 05/07)

7 by 10 LED Moving Sign ( 27c512 Eprom):  (electronic circuit added 4/05)

7 Segment LED Counter:  (circuit / schematic design added 6/06)

700ma Flash LED Driver :  Sipex Application Note  (app note added 2/06)

72 LED Clock:  (circuit added 7/02)

8 Random Flashing LEDs:  This project flashes eight LEDs in an apparently random manner. It uses a 4060 combined counter and display driver IC which is designed for driving 7-segment LED displays. The sequence is not really random because seven of  LEDs would normally be  display segments,  eighth LED is driven by an output that is normally used for driving furr counters. The table below shows  sequence for  LEDs. You can use less than eight LEDs if you wish and  table may help you decide which ones to use for your purpose. (added 6/06)

8 Stage LED VU Meter:  (electronic circuit added 10/05)

9 Second Digital Readout Timer:  (circuit added 7/02)

9 Second LED Relay Timer:  (circuit added 7/02)

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

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