Hello,
I am looking to get started with sound sound based projects and would like to know what the standard output voltage from a 3.5mm jack is.
Thanks....
It is what ever the jack is connected to.
If it is something like an audio output from a playback device ( iPad / pod ) it is likely to be in the range 0.1V to 2V.
If it is a microphone then 1 to 10mV.
So basically no there is no standard.
[u]Line Level[/u] for consumer equipment is 0.316V RMS. This approximately the maximum voltage you get out of a DVD or CD player at maximum volume.
Headphone-out is in the same ballpark (depending on the volume control., etc.) so a headphone output is generally compatible with a line input (the AUX or TAPE input on a receiver). The headphone output on a laptop doubles as line-out. However headphones have lower impedance, so they shouldn't be connected to a line-output.
And of course it all depends on how "loud" the music/program is (and the volume control if there is one).
Manufacturer's follow these standards loosely, but a line-output is usually at least -10dBV (0.316V), and a line-input on an amplifier usually has at least enough gain to hit full power at -10dBV... In other words, line-level outputs are often higher than line-level, and inputs often work at less than line-level. That way, you never have to worry about having enough signal.
Microphone levels vary all over the place, depending on the sensitivity of the microphone and the loudness of the sound. For this reason, all microphone preamps have a gain control. Microphone preamps typically have a maximum gain of 100-1000 to bring the signal up to line level. Under very-loud conditions (such as a mic in front of a loud guitar amp or kick drum) you may get "line level" from a mic.
I would have said 0 to +/-1 to 1.5V.
AC signal out, so you have to level shift it to 2.5V to feed into Arduino ADC.
This can be done passively by passing it thru a capacitor into the junction of two 100K resistors, one resistor to 5V and the other to Gnd so the junction is at 2.5V.
Or use a non-inverting summing op amps so your signal olny sees the high input impedance of the op amp.