Here is some more detail on the stereo sound meter (VU meter).
The circuit that runs the array of LEDs uses two LM3915 ICs, one for each channel. I've worked with this chip before but when I ran across this kit from b2modkits.com I couldn't resist. I had to replenish my stock of blue LEDs as well so I bought a couple of kits and a bunch of 5mm blue LEDs. Assembly was easy and the circuit runs great.
I created a simple splitter out of one of those CD drive audio connectors which allows me to have the VU meter working and have a secondary output for headphones. Swing by your nearest electronics store and pick up a short headphone jack. Cut it to the right length and solder the three wires to the matching three wires on the audio connector. The colors may not match but you should be able to find Left, Right and Ground on both sets of wires. (if you get left and right swapped you can always connect the LED cables to the opposite channel.)
The LEDs have to be soldered to the supplied cables, not too difficult but watch the heat on the LED, burned up a couple by overheating them. (You can see the ones I messed up on if you look at the high res pic of the back of the panel.) I waited to solder the LEDs until I had them mounted to the front panel.
The case had holes in the right places just not big enough, so I used my drill press to carefully drill out the holes I needed for LEDs. I used some LED holders that snap into place if you use the correct drill bit. The LEDs then snap into the holders and can be removed fairly easy if you need to replace them. I highly recommend taking your time with the drilling process. I covered the front panel with paper and tape before I did any rough work with it. (Clamping a unprotected, chunk of brushed aluminum to a drill press is a great way to scratch it up.) I definitely recommend a drill press, I've done it the hard way before with a drill in hand, soon as that bit starts running away you can kiss your straight line goodbye.
Try not to look directly into the beams.
Video
Wouldn't be complete without the video.
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| 30 Meg (1:26) Front view of VU LED meter with panel removed. |