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09-01-2008

LM3915 / LM3916 VU Meter

National Semiconductor » LM3914, LM3915, LM3916

joe

The LED VU Meter was the height of late 80-s boombox technology. This instructable will build one out on the breadboard. Who doesn't like blinking lights...

LM3915 / LM3916 VU Meter

LM3915 / LM3916 VU Meter

You will need either the National Semiconductor LM3916 / LM3915 / LM3914, 2 for stereo...

  • 2x 1.2 kOhm Resistor
  • Wire
  • 2x 10 LEDs or a 10 Segment LED Bar graph
  • 2x Breadboard, or just one big breadboard
  • 2x Stereo 1/8" jacks
  • Optional 2.2 uF capacitor
  • Power supply anywhere between 3-25 V

Wire the LM3916 Circuit
You will wire up the circuit following the diagram attached.

Wire the LM3916 Circuit

Bigger version you can check out here.

I skipped two things, I did not use the capacitor as it is only necessary if you have more than 6" of cable between the LEDs and the chip, and I also did not use the 7.5 k resistor in the diagram going to pin 6/7. your mileage may vary.

3Pass through for sound
I wanted to be able to listen to the music while looking at the flashing lights, novel idea I know...

So I wired up two 1/8" stereo jacks wire the two together, and then hang 3 wires off of one, the negative will go to pin 4 on both chips, while the left signal will go to pin 5 on one chip, and pin5 on the other chip.

I wanted to be able to listen to the music while looking at the flashing lights

WIre the LEDs
Remember the LM3916 switches negative not positive. So hook the positive up on all of your LEDS to positive in your breadboard.

Then pin 1 should go to the first pin on the LED, followed by pins 18-10 so they will light up in order.

As you can see in the second pic, I got a little sloppier on the second set of LEDs and just used wires from a jumper kit so its a little messy.

WIre the LEDs LM3916

Now you can live large like Radio Raheem, this would fit nicely in the ipod nano box wouldn't it...

Except you can't fit 20D batteries in a nano box...

Now you can live large like Radio Raheem

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