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White LED
(White Light Emitting Diodes) Circuits
White LEDs: #-B
C - K L - P
Q - V W - Z
LED Circuits
Last Updated on:
Monday, October 03, 2011 06:08 PM |
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Circuits Designed by Dave Johnson, P.E. : |
- Pot
Controlled Variable LED Intensity Circuit
The circuit below uses power from four rechargeable AA NiMH cells to drive 3
white LEDs. A potentiometer varies the duty cycle of a pulse width modulator
circuit to vary the intensity of the LEDs from 0% to 100%. The beauty of the
circuit is that when the pot is all the way toward 0%, very little power is drawn
from the battery. Likewise, when the pot slider is moved toward the 100% end,
full power is fed to the LEDs. In effect, the pot becomes the on/off
switch....
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Links to electronic circuits,
electronic schematics, designs for engineers, hobbyists, students & inventors:
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LED Buck PFM - 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 mere..... [Circuit by Stepan Novotill] |
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LED dimmer uses only two lines - 21-Mar-02 Issue of EDN
The circuit in Figure 1provides 32 steps of brightness control-from 0 to
100%-for a backlight or instrument panel.... [Design Idea by Jerry
Wasinger, WallyWare Inc, Norcross, GA] |
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LED Flasher - 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] |
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Light a white LED from half a cell - 12-Jun-03 Issue of EDN
Whether you use them as indicators or to provide illumination, LEDs are
hard to beat in efficiency, reliability, and cost. White LEDs are rapidly
gaining popularity as sources of illumination,.... [Design Idea by Anthony
Smith, Scitech, Biddenham, Bedfordshire, UK] |
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Lighting Management System for Six White LEDs & One RGB or Flash LEDs -
National Semiconductor Application Note LP3936 June 2004.....[App Note] |
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Lighting Management System for Six White LEDs & Two RGB or Flash LEDs -
National Semiconductor Application Note LP3933 March 2004.....[App Note] |
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Line Powered White LED Array - There has been a lot of excitement lately in
the lighting industry. Some companies are beginning to manufacture general
lighting fixtures, which replace incandescent and fluorescent lamps, using LED lights.
When proper heat management is designed into the light fixtures, these LED lights can
produce more light with less electricity and last much longer than other devices.
They can also operate well in cold temperatures. Some of these new lighting
fixture designs use a large number of white LEDs, wired into long series wired string
arrays. The circuit below is designed to provide a regulated DC voltage for
these strings. [Designed by David A. Johnson] |
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Line Powered White LEDs - The LED circuit above is an example of using 25
white LEDs in series connected to the 120VAC line. It can be modified for more or less
LEDs by changing the R value. The exact resistance value will depend on the particular
LEDs used. In operation, a DC voltage of around 170 is produced from the bridge
rectifier and 50uF capacitor. The capacitor value is not critical.....(electronic
circuit added 1/06) [Bill Bowden design this one] |
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LM27961-Dual-Display White LED Driver with 3/2x Switched Capacitor Boost -
National Semiconductor Application Note (app note added 2/06) |
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Optical feedback extends white LEDs' operating life - 18-Jan-07 Issue of EDN
PWM-controller loop stabilizes light output..... [Design Idea by Bjoy Santos, Intersil
Corp, Milpitas, CA; Edited by Brad Thompson and Fran Granville] |
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Parallel White LED Driver - National Semiconductor Application Note LM3595
August 2003.....[App Note] |
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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) |
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Pot Controlled Variable LED Intensity Circuit - The circuit below uses power
from four rechargeable AA NiMH cells to drive 3 white LEDs. A potentiometer
varies the duty cycle of a pulse width modulator circuit to vary the intensity of the
LEDs from 0% to 100%. The beauty of the circuit is that when the pot is all the
way toward 0%, very little power is drawn from the battery. Likewise, when the
pot slider is moved toward the 100% end, full power is fed to the LEDs. In
effect, the pot becomes the on/off switch..... [Designed by David A. Johnson] |
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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 mere.....(added 2/05) [Circuit by Stepan Novotill] |
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PWM White LED Drivers - (electronic circuit added 4/05) |
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White LEDs: #-B
C - K L -
P Q - V
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Circuits |
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