Some questions on audio out...

Hi all,

What's the maximum voltage rating of the audio out where we put in our headphone jack? Does it differ for the ones we found in pcs and audio players?

often it's rated in milliwatts out. A common value would be between 200mw to 500mw for a good many headphone jacks. A few of the high-end receivers/amps may yield as high as a couple watts/channel.

A headphone could be 8 ohms or 600 ohms. So the voltage isn't rated, the power into a certain resistance is instead. Usually the output has a series 180 ohm resistor to limit the current. Then if the source has a 10V output, an 8 ohm headphone gets 23mW and a 600 ohm headphone gets 99mw.

If the current-limiting resistor isn't there then the 8 ohm headphone will get 12.5W and blow up (and your ears too). The 600 ohm headphone will get "only" 167mW which is pretty loud.