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LED (Light Emitting Diodes) Circuits   Page 8b
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Last Updated on:
Wednesday, November 29, 2017 05:40 AM

Circuits Designed by Dave Johnson, P.E. :
  • Lighthouse LED Flasher
    This was originally designed for a model in a HO train set.  It simulates the behavior of the light from a lighthouse.  The LED intensity gradually increases, then flashes with a bright light and finally decreases slowly in intensity. 

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

LED Flasher & TRAC Pulser work Off AC Line -  15-Jan-98 Issue of EDN  A flashing LED is an excellent visual alarm. Unfortunately, the LED is a dc device and requires additional circuitry to operate from an ac source. Several circuits can perform the necessary function, but the circuit in Figure 1a...This File contains several Design Ideas, please scoll to this one..... [Design Idea by Dennis Eichenberg, Parma Heights, OH]
LED Flasher (Colin Mitchell) -  This is a very simple project using a printed circuit board and 8 components. It will flash an ordinary 3mm or 5mm (1/8" or 1/4") LED at a rate of about one flash per second….(circuit added 4/08)
LED Flasher 2 -  PIC16F84 8-LED Flasher with three selectable patterns......
LED Flasher 2 Transistor -  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...... [Tony van Roon's circuit]
LED flasher checks fiber-optic strands -  7-Jan-10 Issue of EDN  Send visible light through strands to check for breaks..... [Design Idea by Edwin A Mack, Port Republic, NJ]
LED Flasher Indicates Low Battery Condition -  01/02/97 EDN-Design Ideas.....Many portable electronic devices could benefit from a visual indication when their battery requires replacement. Typical low-battery indicators simply turn on an LED when the battery voltage drops below a certain value. Such circuits actually accelerate the.... [Design Idea by David Johnson, Consultant, Littleton, CO]
LED Flasher with a Slow Rise & Fall Time -  A Simple Circuit Using a 555.....(design added 12/08)
Led flasher with audio -  Schematic only, no circuit description
LED Flashers -  (schematic / circuit added 05/07)
 
LED Flashing sweetheart kit -  LED Flashing sweetheart kit.....
LED Flashlight -  It's a little wisp of a circuit that allows you to drive a blue or white LED from a low voltage. Normally, if you want to light up a blue or white LED you need to provide it with 3, 3.5 V, like from a 3 V lithium coin cell. But a 1.5 V battery like a AA cell simply will not work. But using the Joule Thief, it works like a charm. Not only does it work with a brand new battery, but it works until the battery is nearly dead-- down to 0.3 V. That's well below the point where your other toys will tell you the battery is dead, so it can steal every last joule of energy from the battery (hence the name). To learn how to make one, watch the video, which is available in a variety of formats. ….....
LED flashlights -  schematic diagram of an inexpensive LED flashlight which runs on a single AA cell and has a cluster of 5 LED's…. [Reverse engineered schematic by Stepan Novotill]
LED HeadLamps -  This article includes circuits of DC-DC LED drivers step downs to run LEDs on less than Battery Volts, Boost for above. (added 4/02)
LED Light Dimmers uses only Two Lines -  03/21/02 EDN-Design IdeasThis circuit provides32 steps of brightness control (from0 to100%]for a backlight or instrument panel, using just two general-purpose-micr.....PDF contains multiple circuits, scroll to find the one of interest… [Design Idea by Jerry Wasinger,WallyWare Inc, Norcross, GA]
LED Lights for AC line -  Circuit diagram of an LED night light made by a north american manufacturer. Remarkably it only draws 100mW and has some surge voltage immunity. A clear plastic light pipe is used to diffuse the light from the LED into the room…. [Reverse engineered schematic by Stepan Novotill]
LED Load -  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. ….(design added 11/08)
LED Mood Light -  This circuit makes a nice lamp that consumes little power, runs cool, and has an incredibly long lifetime. The lamp puts out a warm yellow shade of light, the color may be adjusted by changing the number of red or green LED strings.  [Circuit by Forrest Cook]
LED or Bulb flicker shimmer randomly like candle flame or fire  -  This may well be the world's only discreet logic circuit to generate truly random output. It makes an excellent candle flicker light for your Halloween pumpkin, and looks much more authentic than a shimmer light wherever a good a simulated flame effect is required. I do not guarantee the accuracy or safety of any information herein.  (added 2/05) [Circuit by Stepan Novotill]
LED or Incadescent 12 Volt Lamp Fader -  .... 
LED or Lamp Flasher -  Minimum parts counting. Designed for3V battery operation.....
LED or Lamp Pulser -  Astonishing effect4.5 Volt supply.....
LED Oscilloscope -  George Katz of Balgowlah Boys high in Sydney presented a solid state oscilloscope. He says "probably the best advantage is its very small size and the fact that it can run off the power supply of the circuit being tested. Although it has a low frequency range, it can still be used for most circuits. Its poor resolution will still allow for most waveforms to be visualized." ….(electronic schematic added 11/08)
LED Oscilloscope 1 -  Uses a matrix of 100 LED as a display (circuit added 11/06) 
LED 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..... [Bill Bowden]
LED Photodetector -  Using the light-emitting diode as the photodetector (circuit added 11/06) 
LED Pilot Light AC or DC -  LED current is constant between 6 and 8 mA at5 to30Vdc…. [Tony van Roon's circuit]
LED power meter -  Used for testing RF transmitters.....
LED Relay 9-Second Timer -  This circuit provides a visual 9 second delay using a 7 segment digital readout LED. When the switch is closed, the CD4010 up/down counter is preset to 9 and the 555 timer is disabled with the output held high. When the switch is opened,… [Bill Bowden]
LED RF Signal Meter -  (circuit added 6/07)
LED senses and displays ambient-light intensity -  9-Nov-06 Issue of EDN  LED doubles as photosensor and visual indicator of ambient-light intensity..... [Design Idea by Dhananjay V Gadre and Sheetal Vashist, ECE Division, Netaji Subhas Institute of Technology, New Delhi, India; Edited by Brad Thompson and Fran Granville]
LED Sensor Relay Tracker Schematic -  I have been looking for truly low cost and yet accurate conventional solar trackers. The CdS tracker is pretty good but lacks accuracy and sensitivity. I was thinking about using PV cells as the sensor. I was experimenting with LEDs and noticed they generate voltage in sunlight.  Bingo!This got me to thinking..... [The site is owned by Duane C. Johnson]
LED Sequencer -  The model 4017 integrated circuit is a CMOS counter with ten output terminals. One of these ten terminals will be in a "high" state at any given time, with all others being "low," giving a "one-of-ten" output sequence. If low-to-high voltage pulses are applied to the "clock" (Clk) terminal of the 4017, it will increment its count, forcing the next output into a "high" state(circuit added 6/07)
LED shine -  If you wish to have some really nice looking LED's shining out of your equipment panel, you may try the following trick: pass repeatedly a fine sandpaper on the surface of any transparent and clear LED until the same  … (added 9/07)
LED Sign -  uses two LED arrays to form a 7 X 10 matrix. It produces moving messages or animations stored in an EPROM......
LED Strobe -  This circuit drives a high brightness LED as a strobe.  The BD136 (I had one spare) transistor can be used to drive an LED from a higher voltage source than the PIC operates from if required….  (added 6/06)
LED strobe has independent delay and duration -  11-Jun-09 Issue of EDN  High-brightness LEDs, with independent delay and duration, find use in a visual-inspection application..... [Design Idea by Michael C Page, Chelmsford, MA]
LED Stroboscope -  This simple LED Stroboscope circuit which I designed, maintains constant
LED Tester -  ….must register on this site.... [Published in Elecktor July/August 2010]
LED Torch -  Based on the Maxim MAX660, designed to power three 3mm/5mm white LED's from 3V (1.5V min) , intended for replacing incandescent bulbs in small torches…. [Submitted by Andre]
LED Torch -  A common problem with small torches is the short life-span both of the batteries and the bulb. The average incandescent torch, for instance, consumes around 2 Watts. The LED Torch in Fig. 1 consumes just 24 mW, giving it more than80 times longer service from 4 AA alkaline batteries (that is, up to one month's continuous service)..... [Rev Thomas Scarborough]
LED Torch Circuits -  (design added 04/08)
LED Traffic Lights -  The LED traffic Light circuit controls 6 LEDs (red, yellow and green) for both north/south directions and east/west directions. The timing sequence is generated using a CMOS 4017 decade counter and a 555 timer. Counter outputs 1 through 4 are wire ORed using 4 diodes so that the (Red, North/South) and (Green, East/West) LEDs will be on during.... [Bill Bowden]
LED Voltage Indicator -  This teensy little board is only 1 inch (25mm) square, and is handy as a combined power on and low battery voltage indicator. The two colour LED changes from green to red when the battery voltage drops below the adjustable trigger voltage. It's usable between about 6V and 30VDC, and uses a precision LM336Z-2.5 voltage reference. The LED can be reversed so it changes from green to red if the preset voltage is exceeded, if required. (circuits added 09/05)
LED Voltmeter -  Measures voltages up to 199.9V with 0.1V resolution.  (circuit added 8/06) 
LED Voltmeter Expanded Scale (ideal for your car) -  Its Useful to see the charge voltage. This Helps in detecting a Bad Alternator before it creates a dead battery.....(electronic schematic added 12/08)
LED VU Meter -  The circuit is completely conventional, and is based on the application notes from National Semiconductor. The circuit is shown in Figure 1 and as you can see it uses a single IC and a few discrete components. The extra diode (D3) is included to ensure that the DC to the LEDs is almost unfiltered.....
LED Zeppelin -  The name of our game, LED Zeppelin, is a play on words. It comes not from the pop group of the same name but from Graf Von Zeppelin, a German who invented the first rigid air ship in 1900.  The association fits perfectly. The game consists of six LEDs and an indicator LED that flashes at a rate of about 2 cycles per second. A push button is the "Operations Control" and by carefully pushing the button in synchronisation with the flashing LED, the row of LEDs will gradually light up.....(electronic circuit added 2/07)
LED2 LED Sensor Relay Tracker -  Circuit 1 tends to chatter the relays under certain lighting conditions as there is no built in hysteresis.  This version uses a Schmitt trigger hex inverter circuit to eliminate the chatter. It works better but is more complex..... [The site is owned by Duane C. Johnson]
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