LM3915/LM3916 VU Meter

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

I have a bigger project in mind and will post instructables of each piece and tie it all together at the end.

Here is the live action video:

Step 1: Parts

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

-2x 1.2k Ohm 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 2.2uF capacitor
-Power supply anywhere between 3-25v

Step 2: Wire the LM3916 Circuit

You will wire up the circuit following the diagram attached. For a bigger version you can check out the page at N.S..

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 7.5k resistor in the diagram going to pin 6/7. your mileage may vary.

Step 3: Pass 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.

Step 4: 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.

Step 5: Radio Raheem

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...