
         Test points are indicated by *()*          B1 (9V)    B2 (9V)
                                                 +    -   -   +
  ĴĴ/\/\/\
                             390K      1uF 50V             2.2K 
  /\/\/\        /\/\/\((ĴĿ               
    100K    5.6M (Ŀ        -  + /\/\/\  S1    
  /\/\/\Ŀ                               6.8K        
    photo              Ŀ            
    L1463~ĳ    .05uF      9  12 11   6     1                  
     ~~~~   >  Ŀ  50V                  *(6-8V)*  /\/\/\     *
           / S2A  )Ĵ7        U1                 6.8K       A
             R / T    (Ĵ4                         1uF  -/\/\/\ſ
   Ŀ            )Ĵ10      CA3018  *(3-4V, 5ĴĴ 100K 곳
 \ M )                              50 mV    +  ٳ
   i                                       peak to      NPN    
   k                      *(4-5V)*          peak)*     ĳ  PN   
 / e Ŀ   390K         8             3                 >Ŀ2222
      /\/\/\               
           /\/\            -/\/\/\       -  +   
                          6.8K +         390K        Ĵ
                          <-1uF->  +                  1uF
                             -     50V     v 5K  (Note A1)  
                                /\/\/\/\ 
*A is 3-4V,        Ŀ     Ĵ        
    2V peak to peak                           .01             
                               1.5K                            
  (The section in          UUUUUUUU
  the dotted box                 (Audio type matching transformer)
  may be replaced          Ŀ
  with an    .................... 500                
  amplifier) :           1K    :                 S2B/    -+       2K 
             :     UUUUUUUU/  Ĵ/\/\/\/\Ŀ
             :          :    to          R      T 1uF     Ĵ
             :        >     /\/\/\/\Ĵ          
             :            8     : headset    ͳ   47 K   <Ĵ
             :...................:                        PN2907  
                                                            PNP     
   *****                                                        *****
   Emitter is HLMP3750 (visible red)                 1K      ŮĴ
           or XC880    (Infra-red)                 /\/\/\/\Ĵ Ŀ
                                                    /\/\/\ٳ
                                                            27  W
                                  ĴĿ        (NPN    ſD40D5   
                                                 Power Tab) >Ŀ     
                                                       
                          S2C    /                                    
                                / Ĵ
                            R    T      
                                      B3    (6V)

A1   This potentiometer is connected to " S1 ". 
Check Battery " B1 " for approx 2ma (milliampre) (.002 ampre) drain.
Check Battery " B2 " for approx 3 1/2 ma drain.
Adjust potentiometer on base of the NPN transistor untill the emitter
   diode draws approx 20 ma.

Phototransistor and Photodiode may be connected to the main assembly by
a length of shielded mike cable. 

Microphone is a crystal cartridge type (approx 1 inch diam.)

" R " is receive, " T " is transmit.
S2A-C need not be activated to receive. 

Use proper Infra-red lenses. Glass is OPAQUE to I.R. and will SEVERELY
degrade the performance of this device. Visible red may be used.
Red filters over phototransistor will assist the rejection of light
in the visible spectrum, and enhance the funtion of the amplifier.


Good luck. Be careful. I've done my best, but no promises.

(ps. Injection lasers may be substituted for the emitter in this circuit,
with PROPER MODIFICATION).

..

