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Mono VU Meter PCB

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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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Bill of Materials

Qty Part # Description Schematic ID Source
1 A974efb705c2238d6a016c76d206c63269ea15c4 SJ1-3524NG CONN JACK STEREO R/A 4PIN 3.5MM J1 Source
1 3fded271729ab570e419b2879e01e68d9c1b38a3 LM3916N-1 LED BAR GRAPH DRIVER, 3916, DIP18 IC1 Source
1 Cf767e5ea21f9ba1ad6d170149edf00a529c7fbd CT6EP103 TRIMMER 10K OHM 0.5W TH P1 Source
1 274c72f3026c830cb18989b02da51cf2038d2f2d UVR1A471MED CAPACITOR ALUM ELECT 470UF, 10V, RADIAL C1 Source
1 750ce2dcceaf752266214a5e57c209b74d3212d9 BS6I SNAPS 9V 6" LEADS I-STYLE JP1 Source
10 B10fcd91e54061e9748ca26c34782bc79400bf95 WP7113LID 5MM LOW CURRENT RED LED, LAMP THOLE, BULK LED1-10 Source
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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.

Img_0455 Img_0456 Img_0457

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.

Img_0458 Img_0459 Img_0460

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.

Img_0462 Img_0463

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2 - added youtube link
1 - Initial project release
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