Introduction: How to Make a Dual Channel Vu Meter Using LM3914

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In this post i will share on how to make a Dual Channel Vu meter using LM3914 IC. You can watch the video attached along with post for complete construction & working of the project or continue reading the post

Step 1: Components Required

For this project you only need few things

  • 2 * LM3914
  • 2 * IC Socket
  • 2 * 1K Ohm
  • 2 * 10K Trimmer
  • 10 * Green LED
  • 6 * Yellow LED
  • 4 * Red LED
  • 2 * 3.5mm Audio Jack
  • 1 * DC Jack
  • 1 * Switch

You can purchase the above components from the below affiliate links which would help me in lot of ways.

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Step 2: Circuit Diagram & PCB Fabrication

I designed my circuit using KICAD & tested the circuit on a breadboard & then designed my PCB layout & generated gerber & drill files for fabrication. For fabrication i used who provide very cheap & well built PCB's for just 2$(5 piece).

The circuit is constructed mainly around LM3914. For this project i had to use two LM3914 since i wanted separate analyzer for each channel i.e right & left. Each side analyzer is also provided with a trimmer, which can be used to calibrate. This circuit need 12 Volts 1Amp power for operation.

Step 3: Assembly & Testing

After receiving the board i mounted all the components according to their annotation.

After mounting all the components, i connected the circuit to a 12v power supply & then connected the audio input from a laptop & also connected one more input to a amplifier.

Note: After you power the circuit & connect it to a input there should not be any LED On. If there is any LED on then adjust the trimmer such all the LED's are OFF.

After all the connection & calibration are done, then the last thing left is playing a song.

Also Note: when you play a song & if your LED is not reacting then adjust the trimmer until you see the LED On.

Thank You for reading the post