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DiscoverCircuits.com -- Hobby Corner
Last Updated on:
Monday, March 26, 2012 05:23 AM
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More
Flashers/Blinkers;
LED Circuits |
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AC LINE POWERED LED FLASHER NUMBER 3 -- August 9, 2011 |
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Some of the latest LEDs are amazing. They can produce a
surprising amount of light with very little current. In the light flasher
application shown below I take advantage of a nice surface mounted LED from King
Bright. This flasher circuit draws only about 3ua of average current from the
AC power line to flash this green LED. This flasher might be used as a power
indicator light. |
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The
circuit taps a bit of power from the AC line using two 470pF capacitors. A bridge
rectifier, filter capacitor and a zener diode form a 8v DC supply. That DC voltage
feeds a pulse generator set for a 20ms pulse, running at a frequency of about 0.5Hz. It
uses a very low power LMC7215 voltage comparator from National Semiconductor. R3
sets the pulse rate. R6 sets the peak LED current at about 200ua. |
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Click on Drawing Below to view PDF version of Schematic |
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