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White LED
(White Light Emitting Diodes) Circuits page 5a
White LEDs: #-B
C - K L - P
Q - V W - Z
LED Circuits
Last Updated on:
Monday, October 03, 2011 06:09 PM |
| Circuits Designed by Dave
Johnson, P.E. : |
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White LED is Powered by One NiMH Cell
There are a lot of white LED driver circuits floating around. A popular
circuit called the “Joule Thief” can drive one white LED from a single 1.2v or 1.5v
battery cell. Most of these circuits use one or two transistors to form a
voltage boost circuit. Yes, they those circuit do drive a LED but they are not
very efficient and they don’t do a good job of controlling the current to the LED.
The circuit below uses a tiny LT1932 IC made by Linear Technology. This IC can
be configured for a wide variety of LED driver needs. I have shown one simple
application. The circuit takes power from one 1.2v NiMH rechargeable battery
or a 1.5v disposable battery and drives a single white LED with 15ma of current.
With an efficiency of about 70%, the circuit should run for about 40 hours, if a
quality 2500ma-hour battery is used.
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White LED Life Tester
There are lots of white LEDs for sale these days. Many eBay and electronic
component surplus sales claim to sell some very bright devices. Over the years
I have purchased some of them to experiment with. I also have purchased some
products, which contain white LEDs. A major disappointment for me was some LED
night lights I bought from Costco. In just three months of operation, the
night lights I purchased were too dim to be of any use. What I have discovered
is that many of the LEDs.
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White LED Night Light
As many of you know, I have a pet peeve with poorly made LED night lights.
Often, the light from the LED quickly fades, so within months, the light is useless.
I have posted several versions of modified night lights using higher quality
components. This circuit is yet another version, which produces much more light than
those other designs. The circuit brings together two high power white LEDs made by
Cree with a compact AC to DC power supply from Bias Power.....
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Wireless LED Driver
The circuit solves this problem by sending power to the LED through the plastic,
using a magnetic coupling technique. The circuit below can route power through
plastic enclosures as thick as ¼ inch. The circuit will not work through metal
boxes.....
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Links to electronic circuits,
electronic schematics, designs for engineers, hobbyists, students & inventors:
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White LED inductorless drive from 1.5V & 3V - The operating
voltage of white LEDs coupled with my emotional need for low cost for a
given function, motivates me to make LED drivers suitable for battery
operated lanterns that can run from a small number of cells. White and
Ultraviolet LEDs available at the time of this writing, require higher
voltages than colored LED's.....(schematic / circuit added 6/07)
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White LED is Powered by One NiMH Cell - There are a lot of white
LED driver circuits floating around. A popular circuit called
the “Joule Thief” can drive one white LED from a single 1.2v or 1.5v
battery cell. Most of these circuits use one or two transistors to
form a voltage boost circuit....[Designed by David A. Johnson] |
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White LED Life Tester - There are lots of white LEDs for sale
these days. Many eBay and electronic component surplus sales claim
to sell some very bright devices. Over the years I have purchased
some of them to experiment with. I also have purchased some
products, which contain white LEDs. A major disappointment for me
was some LED night lights I bought from Costco. In just three months
of operation, the night lights I purchased were too dim to be of any use.
What I have discovered is that many of the LEDs [Hobby Corner
Circuit by Dave Johnson] |
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White LED Night Light - As many of you know, I have a pet peeve with poorly
made LED night lights. Often, the light from the LED quickly fades, so within
months, the light is useless. I have posted several versions of modified night
lights using higher quality components. This circuit is yet another version, which
produces much more light than those other designs. The circuit brings together two
high power white LEDs made by Cree with a compact AC to DC power supply from Bias
Power..... [Designed by David A. Johnson] |
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White LED Power Supply Design Techniques - TI Application Note (added
2/06) |
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White LED shines from piezoelectric oscillator supply - 10-Jan-08 Issue of
EDN A piezoelectric ceramic buzzer powers a white LED from a single cell.....
[Design Idea by TA Babu, Chennai, India] |
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White LED Step-Up Converter in SC70 & ThinSOT - Linear Technology
LT1937.....[App Note] |
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White LED Stroboscope With Constant Duty Cycle & Constant Current Drive -
Finally, white LED's are bright enough to use in a practical stroboscope. This
circuit can operate as a bench-top stroboscope that, in conjunction with an
oscilloscope or frequency meter and bench top power supply can accurately measure
rotational speeds, or it can be operated hand-held from a single 9V
battery,.....(schematic / circuit added 6/07) |
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White Light LED Driver with Gradual Dimming - TI Application Note
(added 6/06) |
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Wireless LED Driver - The circuit solves this problem by sending power to
the LED through the plastic, using a magnetic coupling technique. The circuit below
can route power through plastic enclosures as thick as ¼ inch. The circuit will
not work through metal boxes..... [Hobby Corner Circuit by Dave Johnson] |
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ZXSC100 Single cell DC-DC converter LED driving applications - Zetec
Semiconductors Applications Notes ZXSC100 single cell DC-DC converter offers an
ideal solution to driving white LEDs in flashlights, enabling operation from a single
NiCd or NiMH cell. (app note added 6/07) |
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