Practice oscillator for morsecode

The practice oscillator is useful for practicing Morse code (CW) transmission. The oscillator generates a sound tone when the Morse key is held down. The tone is adjustable between approx 600-2000 Hz. The oscillator is powered by a 9V battery and is equipped with an on-board loudspeaker, but also has a connector for earphones.

Connections:
KEY 6.3mm mono-connector for Morse key
JP1 2.54mm pin header for alternative connection of Morse key (not included)
SPKR External speaker (not included) - if used do not fit on-board speaker.
PHONE 6.3mm stereo connector for headphone
3.5mm stereo connector for headphone (optional)

Controls:
VOLUME adjust sound volume
PITCH adjust tone frequency