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.
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
Battery Powered Portable VU MeterIn a pinch some of these components may be purchased from RadioShack but your best bet is to buy them from or from Fry’s Electronics, or other equivalent local electronics parts retailer.
I created the PCB artwork in a program called Express PCB, which is available for free download and is surprisingly functional. The resultant artwork is pictured on this page. Next, I printed out the PCB artwork on a transparency. When printing the top copper layer of he PCB within Express PCB, the yellow component outlines are not printed, only the red traces are printed. I then cut out the printed portion of the artwork. This will define the size and shape of the PCB. The third picture is a screen shot of Express PCB showing labels for all of the components.

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