I am trying to built a vu meter using arduino. I came across to this article ( http://theelectronicbyte.wordpress.com/category/projects/vu-meter/ ) the image shows the Signal & Ground connection as the yellow wire (connected to analog pin) and the black wire. I tried to add an audio o/p in place of the voltage divider of the above project.
I wired the mono jack in that manner ( Only the tip & sleeve, no Ring was present) plugged the mono jack to my speaker's additional headphone o/p jack. Connected the other end of "sleeve" wire to the arduino GND & "tip" wire to the ADC pins. I made all the connections exactly as the first image only altered the POT output with the audio o/p. Uploaded the sketch & all the leds glow & remain bright, no changes.
After that I came across to almost another same project. ( http://learningthearduino.blogspot.be/2012/11/arduino-vu-meter-audio-sound-meter-with.html ) but the signal input is totally reversed. "Tip" pin to 5V & "sleeve" pin to ADC pins. I cannot understand why the "Tip" (signal) pin is connected to 5V & Ground pin to ADC. We have to connect the "Signal" pin to ADC to get readings. The second circuit works fine but can't understand the audio o/p (ADC input) connections.
Shall be grateful for any help. Thank you.