‰  NOW 30 WPM  ‰  TEXT IS FROM NOVEMBER 2012 QST  PAGE 55‰

THE TRANSMITTER, AND ROUTING THE SIDETONE TO THE HEADPHONES.  RELEASE THE
TUNE SWITCH AND THE TRANSMITTER AND SIDETONE WILL GO OFF IMMEDIATELY AND
THE SYSTEM WILL CYCLE BACK TO RECEIVE AT THE END OF THE PERIOD SELECTED BY
THE SETTING OF THE DELAY CONTROL.  THE CONTROLLER CAN BE POWERED FROM A
STANDARD 12 V WALL WART POWER MODULE OR FROM THE STATION 12 V POWER SUPPLY.
CONSTRUCTION THE CIRCUIT IS SIMPLE ENOUGH THAT IT COULD EASILY BE
CONSTRUCTED ON A PIECE OF PERFORATED PROJECT BOARD.  I HAVE GOTTEN LAZY IN
MY OLD AGE AND TO SAVE TIME HAVE CIRCUIT BOARDS MADE FOR MOST PROJECTS.
THE PRINTED CIRCUIT BOARD LAYOUT DETAILS CAN ALSO SERVE AS A GUIDE FOR
PERFORATED BOARD CONSTRUCTION.  I PACKAGED MINE IN A NICE BUT RELATIVELY
INEXPENSIVE HAMMOND ENCLOSURE SEE FIGURE 2 THAT IS INCLUDED IN THE PARTS
LIST.  THE 2N4401 NPN AND 2N4402 PNP TRANSISTORS SPECIFIED ARE WIDELY
AVAILABLE.  OTHER GENERAL PURPOSE NPN AND PNP UNITS COULD EASILY BE
SUBSTITUTED.  JUST VERIFY THE LEAD ARRANGEMENT AS IT MAY NOT FOLLOW THE
CONVENTION OF THE TRANSISTORS I USED.  THE RELAYS SPECIFIED IN THE PARTS
LIST K1 AND K2 HAVE INTERNAL PROTECTION DIODES ACROSS THE RELAY COILS AS
‰  END OF 30 WPM TEXT  ‰  QST DE W1AW  ƒ