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  1.             AM LIGHTWAVE TRANSMITTER AND RECEIVER BY JOE SCHARF
  2. -------------------------------------------------------------------------------
  3.                    SCHEMATIC 1  [TRANSMITTER]
  4. -------------------------------------------------------------------------------
  5.             
  6.  
  7.                         MIC*     C1
  8.                          ()     + .1 uF
  9.               |---------(OO)-----|(--------|      +9V
  10.               |          ()                |       ^
  11.               |    R3              R4      |      /|\
  12.               |     5.6K            5.6K   |       |
  13.               *---/\/\/\-------*---/\/\/\--|-------*-------*------|
  14.               |                |           |       |       |      |
  15.               |                |           >R1     |       |      |
  16.               |                |    |---->>>50K    |       >R5    >R8
  17.               |              __|3___|2_    >VAR    |       >1K    >220
  18.               |              \ +   -  /    |RESIST |       >      >
  19.               |               \OP AMP/-----|--------       |      |
  20.               *----------------\741 /7     |               |      |         **
  21.               |               4 \  /       >R2             |     C/NPN    Q1
  22.               |                  \/        >1M        |---------B| TRANSISTOR
  23.               |                  |6        >          |    |     E\ 2N2222
  24.               |                  |         |     C2   |    |      |
  25.               |                  |         |  + 10 uF |    >R6    |
  26.               |                  ----------*---|(-----*-->>>50K   |
  27.               |                                            >VAR   |
  28.               |                                            |RESIST|       LENS
  29.               |                                            |    __|___***  ^
  30.               |                                            |    \LED /    (|)
  31.               |                                            |     \  /    ( | )
  32.               |                                          R7>      \/      (|)
  33.               |                                          1K>  -----|----   \/
  34.               |                                            >       |       LENS
  35.               |                                            |       |      OPT.
  36.               |                                            |       |
  37.               |                                            |       |
  38.               |--------------------------------------------*-------|
  39.                                                            |
  40.                                                            |
  41.                                                         --------
  42.                                                           ----
  43.                                                            --
  44. _______________________________________________________________________________
  45.  
  46. R1-GAIN CONTROL
  47. R6-LED BIAS CONTROL ADJUST R6 FOR BEST SOUND QUALITY
  48. R8-LIMITS CURRENT APPLIED TO LED
  49.  
  50. * - MIC- USE CRYSTAL MICROPHONE OR ELECTRET UNIT (CONNECT RED LEAD TO 9V)
  51. ** - TRANSISTOR - USE A 2N2222 NPN TRANSISTOR.
  52. *** - LED - USE A HIGH-BRIGHTNESS RED OR HIGH POWERED INFRARED LED FOR BEST
  53.             RESULTS
  54. _______________________________________________________________________________
  55.  
  56. THE 741 AMPLIFIES VOICE SIGNALS FROM THE MICROPHONE AND COUPLES THEM THROUGH C2
  57. TO MODULATOR TRANSISTOR Q1.  FOR A FREE-SPACE RANGE OF UP TO 1000 FEET
  58. (AT NIGHT), USE A LENS TO COLLIMATE THE LED BEAM OR USE THIS CIRCUIT AS
  59. AN OPTICAL FIBER TRANSMITTER.
  60. _______________________________________________________________________________
  61.  
  62.                 SCHEMATIC 2 --- AM LIGHTWAVE RECEIVER
  63. _______________________________________________________________________________
  64.  
  65.               |-----------------------------------------|
  66.               |                                         |
  67.               |                                         |
  68.               |                                         |
  69.               |                                         |
  70.               >R1                                       |
  71.               >100K                                     |
  72.               >                                         |
  73.    LENS       |   C1 .1uF                               |
  74.      ^        *----|(---------*-------|                 |
  75.     (|)      C|               |       |                 |
  76.    ( | )     /Q1              |       |                 |        +9V
  77.    ( | )   B|PHOTOTRANSISTOR  |       |                 |         ^
  78.     (|)     E\       |-----|  |       |                 |        /|\
  79.      \/      |       |   __|3_|2_     |                 |         |
  80.    LENS      |       |  4\ +  - /7    |                 |         |
  81.              *-------*----\ 741/------|-----------------*---------*
  82.              |             \  /       |                 |         |
  83.              |              \/6       |                 |         |
  84.              |               |        >R2               |       ------  C2
  85.              |               |        >100K             |         ^^    .1 uF
  86.              |               |        >                 |        ^ |^
  87.              |               |        |                 |          |
  88.              |               |--------*                 |          |
  89.              |                        |                 |       --------
  90.              |                        |                 |         ----
  91.              |                        |             3|\ |           -
  92.              |                        |       |------|+\|6
  93.              |                        |       |      |* \--------------|
  94.              |                      R3<       |      |  /5        C3   | +
  95.              |                     10K<<------| |----|-/|      100uF -----
  96.              |                     VAR<         |   2|/4|              ^
  97.              |                  RESIST|         |       |              |
  98.              |                        |         |       |       8 OHM|---/|
  99.              |                        |         |       |     SPEAKER|   ||
  100.              |                        |         |       |            |---\|
  101.              |                        |         |       |              |
  102.              |------------------------*---------*-------*--------------|
  103.                                                 |
  104.                                                 |
  105.                                             ----------
  106.                                               ------
  107.                                                 --
  108. _______________________________________________________________________________
  109.  
  110. R2-GAIN CONTROL
  111. R3-VOLUME CONTROL
  112. C2-PREVENTS OSCILLATION KEEP LEADS TO BATTERY SHORT.
  113.  
  114. * --- OP AMP --- THIS MAY NOT LOOK LIKE AN OP-AMP BUT IT IS  (VERY HARD TO
  115.                  DRAW THEM ON THE COMPUTER.  USE A 386 OP AMP FOR THIS ONE
  116. _______________________________________________________________________________
  117.  
  118. THIS RECEIVER WORKS BEST IN SUBDUED LIGHT OR AT NIGHT WHEN USED FOR
  119. FREE-SPACE COMMUNICATIONS ALWAYS PLACE A SHIELD OVER THE DETECTOR IF SUNLIGHT
  120. OR BRIGHT ARTIFICIAL LIGHT IS PRESENT.  AN INFRARED FILTER SHOULD BE USED
  121. FOR BEST RESULTS (DEVELOPED COLOR FILM WORKS WELL) UNLESS THE TRANSMITER
  122. LED EMITS VISIBLE LIGHT.
  123.  
  124. CAUTION : THIS CIRCUIT CAN PRODUCE LOUD SOUNDS. DO NOT PLACE SPEAKER CLOSE
  125. TO YOUR EAR.
  126. _______________________________________________________________________________
  127.  
  128. FEEL FREE TO PASS THIS CIRCUIT AROUND AND IF YOU HAVE ANY QUESTIONS OR
  129. PROBLEMS YOU CAN CONTACT ME ON CHUCKS PLACE (304)-776-7078 BY LEAVING E-MAIL
  130. TO:   JOE SCHARF
  131. _______________________________________________________________________________
  132.  
  133.