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Battery Charge Level Monitor
The Battery Charge monitor is built around LM3914 LED Display IC.


The LM3914 is a monolithic integrated circuit that senses analog voltage levels and drives 10 LEDs, providing a linear analog display. A single pin changes the display from a moving dot to a bar graph. Current drive to the LEDs is regulated and programmable, eliminating the need for resistors. This feature is one that allows operation of the whole system from less than 3V.

The chip contains its own adjustable reference and accurate 10-step voltage divider. The low-bias- current input buffer accepts signals down to ground, or V-, yet needs no protection against inputs of
35V above or below ground. The buffer drives 10 individual comparators referenced to the precision divider. Indication non-linearity can thus be held typically to %, even over a wide temperature
range.

The LM3914 is rated for operation from 0C to +70C. The LM3914N-1 is available in an
18-lead molded (N) package.
 

Components Required

IC

LM 3914

1

45

IC

7805

1

15

capacitor

470uf

1

3

Resistor

2.2K

2

1

Resistor

680E

1

1

Transistor

2N3906

1

5

LED

Red

4

3

LED

Green

4

3

LED

yellow

4

3

Potentiometer

10K

2

5