Arduino pin to headphone jack

I have a mono 3.5 mm headphone jack and I want to solder wires on it to go to an Arduino pin for the Tone() function. I was wondering what ohm and wattage resistor I would need to bring down the volume to a good earbud volume. I also have a potentiometer so I would prefer a resistor to get me to maximum volume because I can greater turn down the volume afterwards. I don't know what amperage and voltage audio jacks usually put out.

What is the impedance of the earbud you are using?
You don't want the IO pin to see Less then 180 ohm so you don't overdrive the IO pin.
So your earbud plus a series resistor should measure 180 minimum, then your pot in series should add to that to lower the volume. 1/4 watt resistor & 1/4 watt potentiometer will be fine.

Assuming earphone resistance is 8ohms.

The resistance between the Arduino O/P pin to GND should be: 5v/20ma=250ohms at a minimum.
270 1/4 watt is a standard value.
See image for circuit (a few minutes please).

'Increase' the value of R6 as needed for maximum volume.

You should really have a capacitor in series as the speaker wants ac without a dc-offset. Something like
100uF electrolytic would be suitable.

Done:

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Could somebody please explain why, in the schematic posted by larryd, we need a 1k resistor to GND?

I see no "1k resistor to GND". :astonished:

There is a volume control - if you do not know what that is, then do some research! :roll_eyes: