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.
- LM3914 - https://amzn.to/2GO80Rp
- IC Socket - https://amzn.to/2GFxTBH
- 1K Ohm - https://amzn.to/2XOD359
- 10K Trimmer - https://amzn.to/2GFxTBH
- Green LED - https://amzn.to/2J6ikG5
- Yellow LED - https://amzn.to/2IONUbJ
- Red LED - https://amzn.to/2ZGbGfl
- 3.5mm Audio Jack - https://amzn.to/2DBWuXs
- DC Jack - https://amzn.to/2ZBKH4J
- Switch - https://amzn.to/2WbgXcL
- LM3914 - https://amzn.to/2GQuDVs
- IC Socket - https://amzn.to/2GPtzkD
- 1K Ohm - https://amzn.to/2GSjT97
- 10K Trimmer - https://amzn.to/2GO8nLN
- Green LED - https://amzn.to/2IZY5JP
- Yellow LED - https://amzn.to/2IZY5JP
- Red LED - https://amzn.to/2IZY5JP
- 3.5mm Audio Jack - https://amzn.to/2PA9Sjs
- DC Jack - https://amzn.to/2GOQk8k
- Switch - https://amzn.to/2J6ub6G
- LM3914 - http://s.click.aliexpress.com/e/cDDG9rag
- IC Socket - http://s.click.aliexpress.com/e/bpVtBMFA
- 1K Ohm - http://s.click.aliexpress.com/e/cHb4A04u
- 10K Trimmer - http://s.click.aliexpress.com/e/ch1nCdDA
- Green LED - http://s.click.aliexpress.com/e/bBvCHEys
- Yellow LED - http://s.click.aliexpress.com/e/bgwLt9b6
- Red LED - http://s.click.aliexpress.com/e/cgWIp7Qu
- 3.5mm Audio Jack - http://s.click.aliexpress.com/e/cZ3uwcZi
- DC Jack - http://s.click.aliexpress.com/e/7MNKXqo
- Switch - http://s.click.aliexpress.com/e/bX6ELUrq
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 JLCPCB.com 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