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Indicator Circuits, Page 1
Circuits designed by David Johnson, P.E.
Last Updated on:
Friday, March 12, 2010 12:07 PM
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Dave's Indicator Circuits:
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1.5V LED FLASHER VERSION A
Many published circuits that flash LEDs need 3 volts or more. This circuit
uses only a single inexpensive C-MOS IC and flashes the LED for a full year
on a single 1.5-volt AA alkaline battery cell. The circuit uses a charge
pump technique to provide the LED the needed voltage.
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1.5V LED FLASHER VERSION B
To squeeze even more energy from a alkaline battery cell, this circuit adds
two transistors to a circuit similar to the above design to boost the
efficiency. A small 1.5-volt alkaline N cell should flash the LED for a full
year. It too uses a "charge pump" technique to provide a LED the needed
voltage.
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2 LINE TELEPHONE LINE STATUS INDICATOR
Many home businesses use multiple phone lines. This circuit gives you a visual
indication when a line is in operation. The two AA battery cells should provide
enough power for about one year of operation. The circuit is line polarity
insensitive.
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- 3v Low
Battery Voltage Flasher
Many battery powered devices use two AA alkaline cells. Often you will not
know when it is time to replace the batteries until the device powered by them
actually stops operating. The hobby circuit below can be connected to a 3v
battery, to give you some warning when the battery is nearing its end of life.
It will flash a LED when the battery voltage drops to about 2.4 volts. The
electronic circuit draws only 1ua of current in standby mode and jumps to only
20ua when flashing, so it can safely...
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| Dave's Indicator Circuits:
Page 1,
Page 2,
Page 3 |
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