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Mono VU Meter PCB
By: kurt
A VU meter is used to display the loudness of an audio signal. This open source VU meter lights up ten LEDs to show how loud a mono audio signal is. Two of these can be made to show the loudness of each channel in a stereo signal. This circuit is similar to "Mono VU Meter Breadboard" except it is built on a PCB and requires soldering skills to assemble.
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Files
- VU Meter V1.zip - VU Meter GERBER
- VU Meter.sch - VU Meter EAGLE Schematic
- VU Meter.brd - VU Meter EAGLE Board
Bill of Materials
Qty | Part # | Description | Schematic ID | Source | |
---|---|---|---|---|---|
1 | SJ1-3524NG | CONN JACK STEREO R/A 4PIN 3.5MM | J1 | Source | |
1 | LM3916N-1 | LED BAR GRAPH DRIVER, 3916, DIP18 | IC1 | Source | |
1 | CT6EP103 | TRIMMER 10K OHM 0.5W TH | P1 | Source | |
1 | UVR1A471MED | CAPACITOR ALUM ELECT 470UF, 10V, RADIAL | C1 | Source | |
1 | BS6I | SNAPS 9V 6" LEADS I-STYLE | JP1 | Source | |
10 | WP7113LID | 5MM LOW CURRENT RED LED, LAMP THOLE, BULK | LED1-10 | Source |
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Steps
1. Gather Parts
You'll need 10 LEDs, an electrolytic capacitor (the size isn't critical, but 470uF is recommended), an LM3916, a 10k potentiometer, a 9V battery, a 9V battery clip, and the VU Meter PCB (printed circuit board).
You can get the PCB by going to BatchPCB and submitting the GERBER files above for processing.
2. Solder IC1
Insert the LM3916 as shown. Make sure to line up the dimple on the IC with the artwork on the PCB.
Solder on leg of the IC. Then, push the IC into place while re-melting the solder on that one leg. The solder on that leg will hold the IC in place while you solder the rest of the IC's legs.
3. Solder Audio Jack
I used an LED to prop up the audio jack so that it stayed in the board while I soldered the first leg. I then finished soldering it the same way as the IC in the last step.
4. Solder Capacitor
Insert the capacitor in the position between the IC and the audio jack. Make sure that the stripe on the side of the capacitor is on the same side as the minus sign on the PCB artwork.
5. Solder Potentiometer
Solder the potentiometer in place. The footprint of the pot is not quite the same as that on the PCB, so you will have to bend one leg of the pot to make it fit. Alternately, you can buy a different pot that fits the holes on the PCB.
6. Solder LEDs
Insert all ten LEDs. Make sure the LEDs line up with the outlines on the PCB. The flattened side of the LED should be away from the board edge. Ignore the +'s on the PCB artwork. They are wrong.
Solder the outside leg of each LED. Then push the LEDs into place while remelting the solder on the outside leg. When you've got the LEDs positioned flush against the board, continue soldering the other leg of each LED.
In the photos you can see how the LED's aren't lined up very well at first. After I straightened them out by re-soldering the first leg, they look much better.
7. Solder 9V Battery Clip
Solder the 9V battery clip to the PCB. The black while goes in the hole marked ground. The red wire goes in the hole marked +9V.
8. Use It!
Plug a 9V battery into the 9V battery clip. Plug a stereo y-splitter into the audio jack on the VU Meter. Use a male-to-male 3.5mm audio cable to bring the audio signal from your audio source to the VU meter. Plug the 3.5mm cable from your speakers into the other hole on the y-splitter.
Use a small screw driver to adjust the potentiometer so that the loudest parts of music just barely light up the top LED. Enjoy the show!
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Revisions
2 - added youtube link
1 - Initial project release
Add revision
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