Circuits designed by David Johnson, P.E.
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List of Dave's Circuit Designs
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Flashers and Blinkers
LED (Light Emitting Diodes) Circuits
Super Bright 3v Powered LED Flasher
(April 22, 2009)
|I have posted several kinds
of LED flashers over the years. This is yet one more flasher, designed to flash
any high power LED of any color. It hits the LED with a 25ms 250ma pulse once
every 2 seconds. This works out to an average current about 3ma. It is
powered by any 3v source. I suggest two AA cells but a single 3v lithium coin
type cell will also work. With fresh AA cells, the light should flash for about
two weeks. The light flash is very intense and is perfect for any attention
getting night time application.
circuit uses a TLV3701, which is a nifty single low voltage, low current voltage
comparator from Texas Instruments. I configured the oscillator circuit to produce
the needed pulse signal. A charge pump circuit and an active current limiting
circuit supplies the LED with the needed drive signal, whose voltage can exceed the 3v
from the battery. This method insures that the typical 3.6v required by most white
LEDs can be produced.
on Drawing Below to view PDF version of Schematic