How do I add a headphone output to the Ruby or Little Gem?
You’ll need either an 1/8″ or 1/4″ (depending on the size of the headphones plug) closed-tip, open ring stereo jack. Follow the schematic shown below for the main speaker to be silenced when the headphones are plugged into the circuit. The 10 ohm resistance between the headphone jack sleeve and ground will reduce the headphone output level. However, the headphone jack must be insulated from the enclosure by using non-conductive washers (thanks to Peter Snowberg for this tip!) Be careful! Using headphones at higher volumes can damage your hearing.
