-- Stereo VU Meter
-- 07.31.2003
-- By:
jingoku
-- Page: 1 2 This
is a quick how-to guide for making a stereo VU meter using the
LM3915/LM3916. The LM 3916 is an
integrated circuit (IC) that takes analog voltage levels and drives 10
LEDs, LCDs, or vacuum fluorescent displays to represent digital
voltage levels just like a VU meter. An LM3916 IC will take one signal
source. Thus if you want to display a stereo representation of your
audio, you must install 2 LM3916 ICs.
Click to above to enlarge
This is the schematics of the
circuit I built. Keep in mind what I said earlier about mono, and
stereo.
The 2.2 uF
Tantalum Capacitor is only needed if your wires from the IC to the
LEDs are longer than 6 inches. Although the specs for the LM3916 say
you can use any voltage from 3 V to 20 V, I suggest using at least
12 V to power your circuit.
So before
soldering everything together, let’s just test the circuit on a
protoboard. First let’s get everything ready. The following items are
what we need for this project:
-
LM3916 IC
-
10 LEDs of your choice (5mm
or 3mm doesn’t matter) I chose 2 green, 3 yellow, 3 red, and 2 blue
-
One 1.2 KOhms resistor
-
2.2 uF Tantalum capacitor
(optional)
-
Stereo Jack
-
wire
-
soldering iron and various
cutters
Ok, let’s start
with the assembly.
After getting all the components ready, it is
time to start
prototyping. First to be placed onto the protoboard is
the most
important piece, the LM3916 IC.
Then
put everything else together. Ah, noticed for this
prototype I used 10 5mm blue LEDs. Hurray, the prototype worked. I
hope yours did, too.
Now
it’s time to design the permanent circuit. Here is where you can get
creative, you can arrange them the way you want them, and find
creative ways to put it all together. Here is how I
did mine.
I used DUBOX connectors
(those blue things you see in the picture). By using those connectors
I could just use the wires you see in the next picture (hanging from
the power supply) to change LED color or simply making longer or
shorter wires to reach my LEDs.
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