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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.
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.
Low Power 10
LED Sequential Flasher
A while back I posted a flasher circuit which flashed 10 LEDs sequentially.
That circuit was powered by four AA alkaline cells. The circuit below operates
much the same way but has been modified to run from a single 3v CR2032 lithium coin
cell. The average battery current drain is a low 400uA. Yet, by using
some super bright green surface mounted LEDs from King Bright, the effect is quite
impressive even if each LED is driven with only 2ma of current........
Links to electronic circuits,
electronic schematics, designs for engineers, hobbyists, students & inventors:
LDR & LED Smoke Detector - Smoke detectors are generally used in
advanced alarm systems. Most of this professional devices use
gas-detectors, ionization rooms or radioactive elements as sensors. In
this circuit we are not using any of this complicated components. Instead
of these, we are using two LDRs and one LED. LM1801 special-purpose IC
,which is designed especially for sm....
LED 12 Volt Lead Acid Battery Meter - In the circuit above, a
quad voltage comparator (LM339) is used as a simple bar graph meter to
indicate the charge condition of a 12 volt, lead acid battery. A 5 volt
reference voltage is connected.....(added 05/06/07)
LED Ammeter - Measures current up to 10A with selected 100mA, 10mA and 1mA
resolutions. (circuit added 8/06)
LED Audio UV Monitor - 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.....(added
5/02)
LED Bargraph Optical Tachometer - For the electric R/C enthusiast, a
tachometer can be a very useful piece of equipment. When I first built this tach back
in 1995, it was essential, as there were very few off-the-shelf electric R/C power
systems that just worked….. [Stefan Vorketter]
LED Battery Condition Indicator - In the circuit below, a quad voltage
comparator (LM339) is used as a simple bar graph meter to indicate the charge
condition of a 12 volt, lead acid battery. A 5 volt reference voltage is connected to
each of the (+) inputs of the four comparators and the (-) inputs are connected to
successive points along a voltage divider. The LEDs..... [Bill Bowden's circuit]
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]
