LED VU Meter That Dances to Computer Music





Introduction: LED VU Meter That Dances to Computer Music

This is a cool LED project I am undertaking. The heart of this project is using the LM3914N (or similar) LED driver. Once completed this can be connected to your sound card or can be connected via a microphone element (still working on this part) for some really cool effects lto light up your room. I connected this via 4xAA rechargables. Guilt free power.

This is my first project and my first instructable so bear with me.

Also this is still a work-in-progress since there is so much I plan to do with this project. I will keep updating this if possible with updates such as not relying on a microphone, driving more LEDs, ect.

Step 1: What You Need.

First her is what you will need.
1 - LM3914N LEd driver
1 - 1k resistor
1 - 1M resistor (the picture shows a 10k resistor but I got best results with 1M, play around with this value to get best results)
1 - 1uF electrolytic capacitor
10 - LED (your choice of colors)
Some wire
Solderless bread board or whatever else you want to build on
4 AA batteres

Switch is optional

Step 2: Build the Circuit and Connect the Sound Source

So I followed this schematic when I build the circuit. I used a 6V source (4AA).

Pin 5 may get a little confusing. What happens there is pin 5 goes to node "A". Node "A" attaches to a resistor (1M) which goes to ground. Node "A" also connects to the negative of the capacitor.

Other than that it is straight forwards. The negatives of the LEDs face the chip. The positive ends of the LEDs are connected to the source.

The Input. Now this is porbably the most important step. The input comes from sound card on my computer (to be able to listen and view this effect you need to get this: http://www.monoprice.com/products/product.asp?c_id=102&cp_id=10218&cs_id=1021802&p_id=667&seq=1&format=2&style=

The male end of the above goes to the sound card where you speakers are now. One female end is connected to the speakers you just unplugged. The other end will be this:

You take 1 end of this and cut it and split the wire to look like the picture shown.

Step 3: Turn on Some Songs and Sit Back and Watch

The final circuit is shown here.

This is a note from where I got the circuit drawing: "I like to see lights move to music. This project will indicate the volume level of the audio going to your speakers by lighting up LEDS. The LEDS can be any color so mix them up and really make it look good. The input of the circuit is connected to the speaker output of your audio amplifier. You want to build two identical units to indicate both right and left channels. The input signal level is adjusted by the 10k ohm VR. If you wish to make a very large scale model of this unit and hang it on your wall there is an optional output transistor that can drive many LEDS at once. The unit I built drove three LEDS for each output. The sequence of the LEDS lighting are as follows Pin 1, 18, 17, 16, 15, 14, 13, 12, 11, 10."

I only did this for 1 channel but plan add improvements.

Take a look at the video for results.

Some things I need to fix are:
All of the 10 LED's do not light up. I need to make an amplifier of some sort but dont have too much expierence in this.
Make this work with a microphone element
Add function for two channels
Add multiple LED's in place of each 1 LED (maybe 3x10 = 30LED)
Also figure out how to connect the microphone element as I have no idea what the picture below shows

Step 4: Possible Additions to Project

Here is the mic and other possible 'mic' I have. I wish to implement one of these with the current circuit.



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    Can i use 1.5uF 50v capacitor instead of 1uF?i have a couple of 1.5uF's but not 1uF...

    Great tut. I have done the same thing using LM3914'S in my project. you can connect as many leds to each pin as you can can supply voltage for (max20v) as the ma are user selectable (see data sheet). mine has two leds on each pin at the moment and works fine! during testing I had 4 leds on each pin to see how far it could go!


    This may be a stupid question by where can I buy the LM3914N LEd driver? radio shack doesn't sell them :-/

    Some Lm3914's Are selling as Cheap as 5/$2.50 or 50 cents each.... No Kidding!!!( On E/BAY)

    There is a bunch of sellers at ebay.com ;)

    can i jsut use a PIC?

    You Don't Need To Program a 3914

    if any other ic is there like LM3915 because in india bangalore this ic not available please help me.

    easily available at S.P. road.

    thank you sir for this interresting project
    please can you help me to realise it for 120v because i want to see the different voltage between 120v and 0V on bar graph vu meter
    thank you sir all my regards