Variable Range Bragraph Voltmeter Using LM3914


This is a variable range LED bar graph voltmeter project. It is a simple and less expensive project that displays voltage of a given source with the help of 10 LED’s. The project is based on the famous LM3914 IC from Texas instruments.


The project is used as a Variable Range LED Voltmeter. The LED’s indicate the range of the input voltage applied. A power supply of 12 VDC is applied through the CN2 connector, and the variable input voltage supply is applied to the CN1 connector. IC LM3914 is a dot/bar display driver; it senses the analog voltage levels and displays its range on the LED’s.

The LED’s indicate depending upon the variable input voltage applied. Using the jumper we can select the mode of LED display. When the jumper is open it is in dot mode and when it is closed it is in bar mode. Range adjustable 0-1.3 V and 0-10.8V.



  • Input : 12 VDC @ 190 mA
  • Range : 0 – 1.3 V and 0 – 10.8 V adjustable with onboard preset
  • Output : 10 LED’s
  • Two Modes, Bar and Dot selectable by a jumper
  • Very low current consumption, typical 200 mA
  • Header pins for connecting power and voltage in
  • Four mounting holes of 3.2 mm each
  • PCB dimensions 32 mm x 74 mm






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