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Topic: VU/dB Meter (Read 2835 times) previous topic - next topic

nickjames

I'm new to Arduino but I was wondering if it was possible to create a VU/dB meter using an Arduino mini. I was thinking of having a microphone input and as the sound intensifies so do the LEDs or an LCD Bar screen.

It's a project I've wanted to do for a while but haven't gotten around to it.

Thanks

Nick

mhenstell

Should be possible - might need to preamp the mic to line level, take an analog reading, then do something like "If the level is between x and y, light this many leds." Might get a little tricky because db is logarithmic. Might help to check out a vu meter on an audio mixer, see what dB markings it gives, and match that (by calculating what voltage you should have for that dB marking). It would help even more to have an audio mixer to compare signal reference levels, to make sure it's acting the way it should. Then you could add a peak-hold and realistic ballistics  ;)

macegr

Here is a circuit I developed that works quite well for detecting the current audio level, when fed into the ADC of a microcontroller. I've constructed these and used them for sound reactive projects with great results. Diodes are Schottky, BAT42 or similar. Any diode will probably do the trick, as long as they are the same.

Unique RGB LED Modules and Arduino shields: http://www.macetech.com/store

salsaman

#3
Aug 24, 2008, 10:15 pm Last Edit: Aug 24, 2008, 10:15 pm by salsaman Reason: 1
hmmm... tried this but only had a 741 and got no signal...:(

pulled an rc4558p out of an old boom box but got nothing there either!  i think i'm doing it wrong... huh...

any other resources would be most appreciated!

also-- i feel like there must be commercial devices with this circuit-- like USB headset microphones?  hmmm...
My Arduino blog: http://jmsarduino.blogspot.com
Comprehensive (?) Arduino-compatible board list: http://tinyurl.com/allarduinos

Quijonsith

#4
Aug 25, 2008, 05:38 am Last Edit: Aug 25, 2008, 05:39 am by Quijonsith Reason: 1
macegr, that input circuit looks like just what I need for a similar project.  how would the output be affected by different resistor/capacitor values?  Also, why are there two battery symbols?  I'm planning to use this circuit right after a bandpass filter IC (switched capacitor controlled by arduino for center frequency and Q) to make an audio spectrum analyzer.

*edit* sorry if i'm thread hijacking

salsaman

the question re: the battery symbols is what I was hinting at-- Im not sure exactly how to read it...

I picked up an LM324 today though-- will breadboard it again with that and report back...
My Arduino blog: http://jmsarduino.blogspot.com
Comprehensive (?) Arduino-compatible board list: http://tinyurl.com/allarduinos

macegr

That schematic is an LTSpice simulation. One of the voltage elements is used to power the op-amp, the other voltage element is reading a WAV file on my computer and varying 1 Vpp accordingly. I have built the circuit exactly as shown above and it works well. Simply remove V2 and substitute one channel of your audio output. This has no gain control, so you need to adjust the volume that is output from your headphone jack.
Unique RGB LED Modules and Arduino shields: http://www.macetech.com/store

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