C P O

WHAT IS A( CPO ) CODE PRACTICE OSCILLATORS.  IT IS JUST A SINE WAVE OSCILLATOR 
THAT YOU TURN OFF AND ON. BUILDING A SINE WAVE OSCILLATOR IS VERY EASY. BUT
TO BUILD  A CPO THAT SOUND LIKE CW  THAT COME OUT OF A RADIO IS VERY HARD. A 
CPO WITHOUT CLICKS OR FREQUENCY SHIFTING ON STARTUP AND  THUMPING IS VERY
HARD TO DO WITH A SIMPLE CIRCUIT.
  A GOOD CODE PRACTICE OSCILLATORS SHOULD SOUND JUST LIKE CW  THE REAL THING
THAT BEING THE CW WITHOUT ANY KEY CLICK OR THUMPING WHEN KEY MAKE AND BRAEKS
CONTACT. IF YOU HAVE BUILD A CPO BEFORE YOU MITE KNOW WHAT I AM TALKING 
ABOUT. IT IS VERY HARD TO LEARN CW CODE WITH A BAD CPO BECAUSE  OF THE THUMPING 
SOUND IT MAKE MITE  SOUND  LIKE A DIT. OR MITE NOT BE ABLE TO HEAD THE FIRST DIT
BECAUSE OF THE THUMP OR KEY CLICK..
   THIS  CODE PRACTICE OSILLATORS HERE IS VERY SIMPLE TO BUILD AND HAVE VERY 
GOOD SOUNDING  CW TONE WITHOUT ANY KEY CLICKS OR THUMPING.I DID NOT DESIGN
THE CIRCUITS IS FROM  FEBRUARY 1987 OF QST. MORSE MASTERII . I BUILD ONLY THE 
OSCILLATOR PART OF CIRCUIT AND IT THE BEST SOUNDING CPO I HAVE HEARD.

THE CIRCUITS USED A LM555 (U4) FOR THE AUDIO  OSCILLATORS THAT RUN ALL THE TIME.
KEYING THE INPUT OF Q4 THROUGHT THE COMBINATION OF C8,R10 AND R13 PROVIDE
THE 5-MS RISE AND FALL TIMES FOR THE MORSE SIGNAL REDUCING THE LOW FREQUENCY
THUMPING. THE LOW-PASS PORTION OF THE FILTER R29,C11,R20,C12,R21 AND C13 IT 
REMOVES THE HARMONICS OF THE SQUARE WAVE PRODUCED BY U4. THE HIGH-PASS
PORTION OF THE FILTER CONSISTS C10,R18,C21 AND R22. IT'S JOB IS TO ELIMINATE ANY
LOW FREQUENCY THUMPING WHICH C8 DIDN'T COMPLETELY REMOVE. SOMETIME YOU
MITE HAVE TO USE A SMALLER CAPACITOR FOR C8.
  I HAVE BUILD A COUPLE OF CPO AND THEY ALL HAVE SOUND GREAT. SO I DESIGN A 
PRINTED CIRCUIT BOARD  TO MAKE BUILDING  IT A LOT EASYER.