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

Last Updated: June 02, 2021 01:45 PM

Circuits Designed by Dave Johnson, P.E. :

 Transmit to a Remote LED Indictor LightThere 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 . . . Hobby Circuit designed by David Johnson P.E.-December, 2008

TV_Fake_Camera_Flasher -  After having my doorbell rung several times in the middle of the night by some kids, I decided to install some fake TV cameras around the outside of my house.  I was not satisfied with the LED lights on the cameras.  The heavy current drain of the original circuit meant I would have to replace the battery every few months.  So, I removed the original LED driver and added my own simple flashing circuit.   . . . Hobby Circuit by David Johnson P.E.-August, 2017


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

Transmit to a Remote LED Indictor 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 . . . Hobby Circuit designed by David Johnson P.E.-December, 2008

TRIAC Dimmable 20W Offline LED Driver using the LT3799 -  This circuit shows a complete LED driver solution.  The LT3799 senses the output current from the primary side switch current waveform.  The IC regulates the output current by adjusting the peak switch current and the duty cycle through a novel feedback control.  Unlike other primary side sensing methods that need to know input power and output voltage information, this new scheme provides much better output current regulation since the accuracy is barely affected by transformer winding resistance, switch RDS  (ON) , output diode forward voltage drop and LED cable voltage drop__ Linear Technology/Analog Devices App Note, Jul 1, 2011

Tricolor LED emits light of any color or hue -  09/09/10 EDN-Design Ideas Vary the current in three LEDs to produce any color.    Design by Marián Štofka, Slovak University of Technology, Bratislava, Slovakia

Tricolor LEDs Create a Flashing Array -  24-Jun-10 EDN-Design Ideas You can build a matrix of RGB (red/green/blue) LEDs using a simple and inexpensive circuit comprising the control logic and driver circuit in Figure 1 and some LEDs (Figure 2) .  The center RGB LED is the first to come on, after which each sequential LED in the 8×8-LED matrix follows.  This process gives the appearance that the display is alive and moving outward.  This sequence repeats, producing a rainbow effect of colors Design by Jeff Tregre, www/BuildingUltimateModels/com, Dallas, TX

Trip the Light Fantastic with LED Gadget Freaks -  Here is a collection of the best LED gadgets that have made themselves home in Gadget Freak.  

TV_Fake_Camera_Flasher -  After having my doorbell rung several times in the middle of the night by some kids, I decided to install some fake TV cameras around the outside of my house.  I was not satisfied with the LED lights on the cameras.  The heavy current drain of the original circuit meant I would have to replace the battery every few months.  So, I removed the original LED driver and added my own simple flashing circuit.   . . . Hobby Circuit by David Johnson P.E.-August, 2017

Twi-Light using White LEDs -  This sunlight-controlled lamp uses a light-dependent resistor  (LDR) as the sunlight sensor and a total of 25 high-brightness white LEDs.  Separate resistors are connected in series with each row of the...__ Electronics Projects for You

Twinkle Twinkle X’mas Star -  Christmas just would not be Christmas if you do not put a flashing star on your Christmas tree.  Here is the circuit of such a flashing star.Fig.1 shows the circuit...__ Electronics Projects for You

Two LED trouble light systE - M -  No circuit description, schematic only__ CdS Electronic

Two LEDs Perform Rudimentary Spectral Analysis -  09/01/94 EDN-Design Ideas A pair of LEDs having different wavelengths can supply the stimulus for a rudimentary spectral analysis during quality-control sorting operations.  By measuring the reflectance of each LED, the circuit in Fig 1 can provide information about the spectral response of the object under test.  The circuit's Design by Peter Bojilov, Isomatik Sortex Ltd, Pazardjik, Bulgaria

Two PIC pins drive six LEDs -  06/09/14 EDN-Design Ideas Here’s a take on LED multiplexing with minimal output pins.  This Design Idea demonstrates a new method of driving six LEDs with only two I/O lines from a microcontroller, and so is particularly suitable for any pin-limited chip.  It uses a pair of I/O lines combined with a pair of complementary bipolar transistors.   Design by Benabadji Noureddine

Two Signals Easily Control Tricolor LED -  09/14/95 EDN-Design Ideas Tricolor LEDs come in two- and three-pin packages.  Although the three-pin, or common-cathode, package easily lends itself to 2-bit control, wiring three crowded pins can be mechanically difficult.  Also, fewer manufacturers produce the three-pin types.  The two-pin package is easier to connect to a wiring harness and is readily available.  However, this package requires more control overhead, because, to light the LED yellow, the device must continuously alternate between red and green.   Design by Bob Richards, Digital Audio Corp, Raleigh, NC

Two Transistor Flasher -  The basic two-transistor flasher shown below has found its way into dozens of applications due to its simplicity and versatility.  Applications have included such diverse circuits as a micropower low battery indicator, a lightning detector, a off-line.   __ Contact: Charles Wenzel of Wenzel Associates, Inc.

Two Transistor LED Flasher -  This circuit will flash a bright red LED as an attention getting device or fake care alarm. __ Designed by Bill Bowden

Two Transistor LED Flasher 1 -  Circuit Only __ Designed by Tony van Roon  VA3AVR

Two Transistor LED Flasher 2 -  This circuit will flash a super-bright LED  (5000+ mcd) .  Good for fake car alarm or other attention getting device.  Component values are not critical, try anything else first from your junkbox.  Obviously, the 470 ohm resistor  (R3) determines the LED's brightness and limits the current flow to about 20mA.390 ohm can also be used as a save value.  If you decide to go with a green or yellow led, which draw more current, you may want to replace the 470 ohm with an appropriate value.  Flash rate is determined by R2 and C1 __ Designed by Tony van Roon  VA3AVR

Two transistor lights LEDs -  04/09/09  EDN-Design Ideas A previous Design Ideasdescribes a circuit that uses an astable multivibrator to drive an LED    (Reference 1].  The circuit in Figure 1 uses a simpler alternative approach.  The circuit uses a 2N3904 NPN transistor and a 2N3906 PNP trans Design by Barry A Tigner, Michigan State University, East Lansing, MI

Two-LED Pilot Light -  230 or 115 Vac mains operated Very simple circuitry __ Contact: Flavio Dellepiane, fladello @ tin.it

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