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Dave's Indicator Circuits: Page 1, Page 2, Page 3 |
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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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