P a c C o m m   P a c k e t   R a d i o   S y s t e m s


                        Applications Note

                Conversion of Tiny-2/Micropower-2 
               "Connected" signal to RS-232 Levels

Applicability: ONLY those Tiny-2/MicroPower-2 models 
               with TMR-1.1 or TMR-1.2 circuit boards

     The  following circuit may be affixed to the bottom  of  the 
circuit board to cause the "connected" signal (P4, pin 1) to rest 
at  a negative voltage, and to swing well positive when a  packet 
connection exists. 

     If  you desire to retain the TTL level connection signal  of 
P3, you must sever the trace to P4, pin 1 near where it  attached 
to the pin. Be careful NOT to sever the connection past the first 
via (feedthrough hole).

     Spread  the  transistor  pins  to  to  reach  the  following 
locations:

     1. The emitter to +5 volts. Reccommended location is 
          MAX-231 pin 13.
     2. The base through a long wire to a 10k resistor to 
          U15, pin 3.
     3. The collector to P4, pin 1 AND through a 10K 
          resistor to U15, pin 3.

Parts required: 2N3906, 2 x 10K resistor, 1/4 W 5% resistors, 5 
inches light guage (#30 wirewrap) wire, several small peices of 
heatshrink tubing or insulating tape.


                        SCHEMATIC DIAGRAM

                                          10K  -12v

                                       |--/\/\/\--> U15 Pin 3
                                       |
                                       |
                                  ___  o-----> P4 Pin 1
                                 /   \/
                    10k         /  | /\
                               |   |/  |
    U6 Pin 10 <---/\/\/\/--o-------|   | 2N3906
                               |   |   |
                                \  |<  /
                                 \___\/
                                      \
                                       o +5v
                                         U15, Pin 13