Vumeter Light Deco

Introduction: Vumeter Light Deco

About: I like to play with electronics and other fun stuff, modify things to make them more useful or just more funny, putting things together that seem not to fit to make funny stuff. Sharing ideas make the world ...

I will show you how i made this nice and easy to make light-decoration for your next party or just for your living room. The lamp lights up in a vumeter-style when music is playing - in fact it IS a vumeter... For that reason it needs an audio input you have to connect it to the line-out of your music device.

See the video to get an idea of it:

Step 1: Parts, Tools and Skills

10 LEDs
1 Current limiting resistor (R1) - value depends on your LEDs
1 2,2µF Capacitor
1 LM 3915
1 mono audio jack with cable
some pieces of wire
1 piece of protoboard like the Mini Board from Radioshack
1 soldering strip (i used it because i had one, you could also use a piece of cardboard)
1 little switch
1 piece of sandwich paper or similar kind of paper
1 high glass or glass cylinder
1 9 V Block battery and battery clip

for testing the circuit before soldering a simple breadboard could be fine.
1 piece of black paper for holiday decoration

Soldering iron and solder
Wire stripper
Hot glue gun
Diagonal Cutters

"Handy Hands" or "Third Hand" (if you like you could build your own)
Desoldering tool


- you should have basic soldering skills (Instructable How to solder)
- using your multimeter (Lady Adas Multimeter How to)
- some basic informations about LEDs (LEDs for beginners Instructable)

Step 2: Building the Circuit

First of all i builded the circiut on a breadboard. The circuit is based on the vumeter circuit of the instructable over there. Thanks to Joe! There you'll find the diagram and how to breadboard.

Like Joe i didnt use the resistor R2.

The resistor R1 (see on the image) limits the current for the LEDs. In my case a 100 Ohm resistor works fine. You should calculate the value for your LEDs. If you dont know how to calculate it, you could read the instructable "LEDs for Beginners" of noahw, or you simply use an online led calculator like this.

You simply need three values: the source voltage is the voltage of our battery (9V). The diode forward voltage and diode forward current you find on the datasheet of your LED. If you dont have any datasheet you can get experimental and simply try out some resistors. If you have standart LEDs 1k could work fine (no warranty!).

The LEDs must be connected in the right direction. The cathode goes to the chip and the anode to the power bus (+9V) of the breadboard. In most cases the cathode leg is the shorter one.

Also the capacitor has to be connected in the right direction. On the cap you can see a "-" - this is the negative side and it goes to pin2 of the chip. The positive one goes to +9V - connected to the LEDs.

Test the circuit:

Connect the audio jack to any audio souce (e.g. the line out of your computer, hifi-amp or the headphone out of your mp3-Player). Now connect the 9V battery to the breadboard. As you can see on the image in my cast the positive wire goes to the upper line and the negative to the downer line of the power bus.

If it doesnt light up, check the connections, the direction of the LEDs and capacitor.

Step 3: Solder the LEDs

Okay, lets start building the lamp.

First we solder the LEDs to the soldering strip. Be careful to solder all LEDs in the same direction. Then connect the anodes of the LEDs using small pieces of wire.

Step 4: Solder the Circuit

I soldered the circuit on a piece of protoboard (its like the miniboard from Radioshack), but you may make your own board or use other protoboards. The easiest way is to use a breadboard-styled protoboard like that one, where you simply can follow the design of the breadboarded circuit.

Whatever you do - i did it my way (see images below).

I added a power switch so i can easily turn on and off the lamp.

After finishing soldering you should test the connections using your multimeter.

Step 5: Connect the LEDs

Solder the wires for the LEDs to the board and the solder them to the negative legs of the LEDs. Mention the right pins. The wire from pin 1 goes to the first LED, the second LED is connected to pin 18, the third pin 17 and so on. Also solder the +9V-wire to the LEDs (see image)

Dont forget to solder your audio jack to the board. It's connected to pin 4 (GND) and pin 5 of the chip.

Now its time for testing the lamp again. Connect it to your audio source and the 9V battery. If it doesnt light up check the connections using your multimeter.

Step 6: Glue It Togeter

If everything works fine, hot glue the circuitboard to the soldering strip. You may like to  fix the battery to the soldering strip with a wire stap.

Now attach the device to the glass. Hot glue it to the glass so it stays in place.

Then take your bread paper and attach it to front the glass. Also glue the aluminium foil to the back side (used as a reflector). Now your lamp is ready to light! Connect it to your audio source and turn it on.

Step 7: Improvements and Ideas

If you like, you could cut some stars out of a black paper. Attach it to the front of your lamp to have a nice blinking holiday deco.

If your VuMeter Lamp shines not bright enough, you could add more LEDs or use more powerful, brighter LEDs.

So have fun building your Vumeter Light Deco! Leave a comment if you like it or post fotos if you build one! And please excuse spelling and mistakes, i am not a foreign english speaker, so what?!

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    2 Discussions


    10 years ago on Step 2

     I will be using 5 green leds(link) 2 yellow leds(link) 2 orange leds(link) and 1 red led(link). I believe the yellow, orange, and red have the same specs. but the green one is different. What kind of resistor should I put. and by you saying 100 ohm resistor do you mean per led then times that by 10?


    Reply 10 years ago on Step 2

    No the current limiting resistor is R1 on the photo. Its attached between pin 7 and pin 8. This one "programs" the chip to limit the current of all LEDs with the same value. Id recomment you to study the datasheet of the chip over there. Sorry, i cant give you detailled informations, because i just tried it like Joe did.