Picture of Battery Powered Portable VU Meter
What follows are instructions for constructing a battery powered portable VU meter, as well as detailed instructions for the construction of the PCB needed to complete this project. It was designed to illuminate from 0-10 LEDs depending on ambient sound levels. I designed it to be attached to a wristband, clothing, or a necklace if the design is scaled down somewhat. Its purpose is to be worn in a nightclub or similar locale where music is playing, as an animated alternative to a glow stick. It can be used, however, for a variety of alternative purposes.

Step 1: Materials Required

Picture of Materials Required
SMT Components.JPG
UV Exposure Board.JPG
Processing Chemical Bottles.JPG
For this project, you will need the following materials:
1. 1 LM3916 IC
2. 1 LM386 IC
3. 10 LEDs
4. 1 UV Reactive PCB Board
5. 1 18 pin IC socket
6. 1 8 pin IC Socket
7. Various SMT Resistors
8. 1 Dremel tool
9. 1 UV Exposure box
10. Developing chemical
11. Etchant (I use Ferric Chloride)
12. 1 Fine soldering pencil
13. Fine silver-bearing solder
14. 4 3v coin cell batteries
15. 2 Sockets for 2 coin cell batteries each
16. 1 switch
17. 1 electret microphone
18. 3 (1 uf SMT capacitors)
19. Denatured or Isopropyl alcohol
In a pinch some of these components may be purchased from Radioshack but your best bet is to buy them from DigiKey.com or from Frys Electronics, or other equivalent local electronics parts retailer.
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nicholasm2 years ago
are you using ExpressPCB?
teebhai3 years ago
there are many other ways of etching a pcb, y u used a specific uv board for a simple project
for this perf board would have worked without a problem, yea?
ltelaprolu3 years ago
i connected the circuit but only 1st led is working :( may i know the reason?
bad mic
candelo3 years ago
Great project! take a look my similar project

ltelaprolu3 years ago
i connected the circuit but only first led is glowing actually blinking :( is there anything wrong in the curcuit posted above? did anyone try it?
tjmortenson3 years ago
Could you post a file for the pcb?
Blue_Flame3 years ago
Hi there Vlorbschnat

is there a way of driving multiple LED's off of one output (i.e. 10 LED's per output pin)?

I know that I will probably need to increase the drive or gain but as I haven't fiddled around with electronics for a few years my mind needs a refresher!

Many thanks

You could use a simple transistor like the 2n2222
hey guy please give pdf file of pcb artwork..............
skeva944 years ago
Link for PCB???
make your own?
skeva944 years ago
PCB link for PRINTING...
Skyyl4 years ago
What kind of LED's did you use, does it matter?
Vlorbschnat (author)  Skyyl4 years ago
Some colors of LEDs require a different voltage, but it should be safe for the vast majority of LEDs
alright thank you! quickest response iv ever gotten on here =]
Demircat6 years ago
Could you post a schematic/circuit diagram? Thank you!
Vlorbschnat (author)  Demircat6 years ago
Actually, another Instructables member has already posted a schematic, you can find it at http://www.instructables.com/files/orig/FX5/67GS/FLROK12R/FX567GSFLROK12R.gif
Ahh okay, is it that your schematic calls for 6v while this one calls for 9v? Thanks again!
Vlorbschnat (author)  Demircat6 years ago
The components should run off of either 9V or 6V, I just used 6V because the coin cell battery holders I had had 2 3V batteries in series.
sorry I use lm3915N-1 and it doesn't work,i must replace it by Lm2914?

it wont really work 'cause you used LM3915.....read the materials needed again it says lms916.....hope it helped
lm3914 works better
phew!.....i thought it only runs through 12 volts 'cause there are 4pcs 3volts batteries then in my place those types of batteries like CR2032 costs 80php (almost 2 dollars)..good thing i saw this comment!...
The schematic does not match your PCB board. You have totally different resistor and capacitor values. I think yours makes more sense though.
LiLGq4 years ago
i only have one comment for you sir........."SUPER"!!!!!!this instructable is the best......iv'e been searching for thing like this that a speakers which has sorts of LED that blinks from the grooves of the music..............
LiLGq LiLGq4 years ago
another thing is, is it possible to replace the electret mic and attach the two wires to the speakers?.
Vlorbschnat (author)  LiLGq4 years ago
Sure, that should work fine
handyman295 years ago
Are the two 1uF capacitors polar or non-polar?
handyman295 years ago
Can I use ceramic capacitors for the non-polar capacitors?
Vlorbschnat (author)  handyman295 years ago
Yes, ceramic capacitors are non-polar capacitors
handyman295 years ago
Can it run off of a 5vDC adapter?
Vlorbschnat (author)  handyman295 years ago
I think that should work, it was originally designed for 6V but 5V is close enough that it should still work.
handyman295 years ago
Can I use regular capacitors instead of SMT caps?
Vlorbschnat (author)  handyman295 years ago
Sure, it should be fine to use through-hole components instead of SMT components.
Zem5 years ago
 I kind of want to scale the size up a bit, to have it be stationary or on a wall or something, so could I use thru-hole Resistors if I scale up? (I dislike surface mount components)
Vlorbschnat (author)  Zem5 years ago
Sure, I actually used through-hole components for the prototype version, so it should be fine to use all through-hole components.
thank you! i was wondering this myself, as i have absolutely no experiance with surface mount components.
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