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Text File  |  1992-12-05  |  2KB  |  56 lines
  1. Simple code oscillator driven from the COM port of a PC.
  2.  
  3.  
  4. DB-25
  5. FEMALE
  6.              1N4001
  7. |=====|
  8. |     |       |\ |
  9. |     |_______| \|____________
  10. |  4  |       | /|       |   |
  11. |     |       |/ |       |   |  555
  12. |     |              ____|___|______
  13. |=====|             |               |
  14. |     |             |    4   8      |
  15. |     |             |               |
  16. |  7  |-------------- 1             |
  17. |     |      |      |               |
  18. |     |      |      |               |
  19. |=====|      |      |               |
  20.              |      |    6   2   3  |               1/8" stereo
  21.              |      |_______________|               headphone jack
  22.              |           |   |   |           
  23.              |    ||     |   |   |    ||                       |
  24.              |____||_____|___|   |____||____________|-----V    |
  25.              |    ||       |     |    ||            |---v      |
  26.              |    ||       |     |    ||                       |
  27.              |             -\/\/\-                  ___________|
  28.              | 0.001 uF             0.01 uF         |             
  29.              |   film        680k   cer. or film    |
  30.              |               ohms                   |
  31.              |                                      |
  32.              |______________________________________|
  33.  
  34.  
  35.  
  36.  
  37.  
  38.         This easily fits inside the DB-25 shell.
  39.         Adjust the 680k ohm resistor to change the pitch--
  40.         higher value for lower pitch, etc.
  41.         Decrease the value of the 0.01 uF cap. for lower volume.
  42.  
  43.         Essential SETTINGS (for IBM PS/2, probably for clones too): 
  44.  
  45.                 Keying Port  : <your choice from what's available>                
  46.                 Output Keying: ON
  47.                 RS-232 Output: RTS
  48.                 Output Sense : -
  49.  
  50.  
  51.  
  52.         I use this with the prompt sound off and the speaker off
  53.         to practice in the office during lunch.
  54.  
  55.         Jeff Furman, KD6MNP.
  56.