Building an LED VU Meter: LEDs Building an LED VU Meter: LEDs

What You'll Need
LM3916 IC
LM386 IC
10 LEDs
UV PCB Board Reactive
18 IC pin socket
8 IC pin Socket
Various Resistors SMT
Dremel tool
UV Exposure box
Developing chemical
Etchant (Ferric Chloride)
Soldering pencil - Fine
Silver-bearing solder - Fine
Denatured or Isopropyl alcohol

VU meter was first introduced in the 1930s as a tool to level the communication of sound frequency. Before, VU meter used compass needles to indicate the level of sound. However, in development of technology LEDs replaced this mechanical device. The VU meter is not just a tool for measuring overall loudness of an entry, it also gives you the average peak of sound which then helps avoid hitting the meter’s red zone when recording.

Step 1 – Prepare the Artwork, PCB

You may get this on the Internet. Just browse and print it, and you will be able to get an express PCB. You then need to cut it out following the outline.

Step 2 – Cut and Prepare the PCB to Expose it

Make an outline on the PCB reactive copper making sure that you drew it on the protected side. Just follow the pattern of the printed PCB. Use the dremel tool with diamond wheel attachment, cut the drawn outline. However, when you pull out the PCB reactive copper’s protection, you need to make sure that it is not exposed to UV. So you must do this inside the house or the garage preferably. Have an incandescent light on for illumination because fluorescent and halogen produces UV as well.

Step 3 – UV Exposure

You now need to take off the PCB reactive copper protective layer. Put in the positive transparency just above the board and put it inside the exposure box for UV. The allowable exposure time is 10 to 11 minutes.

Step 4 – Chemistry

Combine the developing chemical with adequate water according to the chemical’s instruction. Store it in plastic bow or dish that is big enough to accommodate the PCB. Then get another plastic container and fill it with water. Get another dish of the same size and fill it with Etchant. When you are done, remember that the blue colored solution is for developing, the water is for rinsing, and dark brown is the Etchant.

Step 5 – Develop and Etch

When the board is exposed, you can now soak it in the developer agent until the necessary traces on the board are the only trace there is. Now you can rinse it. Then drop it into the etching solution, making sure that you check out on it for every 30 minutes and then rinse. Clean it up using the alcohol; just remove the excess traces without interfering with the desired trace.

Step 6 – Drilling

In drilling, it is best to use press drill. Use a 3/32 inch drill bit. Just follow the marking on the PCB board.

Step 7 – Solder

Warm up the SMT pads and then place the LEDs in place using fine pliers. Melt down some solder to hold it into place. Allow it to cool and continue with the other LEDs.

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