LED Voltmeter using LM3914 LED Bar Graph

Ferry's picture

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Joined: Sep 20, 2018

Replies: 8
LED Voltmeter using LM3914 LED Bar Graph
September 20, 2018 - 2:24pm

Hi, i want to design a 18V voltmeter or you can say a battery voltage indicator using LM3914 LED Bar graph... i have checked a circuit which is showing a maximum of 5V on the bar graph connected with Arduino..

The voltage is sensed by the analog pin of the Arduino Uno and then further display on bar graph accordingly..

As far as i know analog pin of arduino uno can sense only upto 5V... but i need to display  a maximum of 18V... So is there is any possible way to do the same

or can i use any other microcontroller.... its better if you suggest me a solution with Arduino bcoz the programming an Arduino is simple..

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Joined: Apr 17, 2018

Replies: 109
Measuring more than 12V using LM3914
September 21, 2018 - 11:06am

The LM3914 is a Dot/Bar LED display driver, it can directly glow the LED in a logical fashion based on the input voltage, hence these IC can also operate independently without a microcontroller like Arduino. You can refer the below article

https://circuitdigest.com/electronic-circuits/lm3914-voltmeter-circuit

However one single LM3914 IC can measure only a maximum of 12V, if you application requires you to measure more than 12V (18V in your case) you can cascade two of these IC and get away without a MCU in our circuit.

But, If you interested in using a MCU platform like Arduino then operate this IC in 5V since Arduino can only generate 0-5V. Also Arduino can only read from 0-5V. So use a potential divider circuit to map 0-18V to 0-5V and read it using the ADC feature of Arduino. Then you can use the PWM feature with a RC filter to produce the same 0-5V and drive the LM3914.

Keep in mind it is totally pointless to use an Arduino in this type of circuit as it practically does not have any use