The schematics shown below indicate pin numbers for 6-pin
DIP IC's available at RadioShack.Com stores (1-800-877-0072)
or DigiKey (mailorder 1-800-DIGI-KEY).
- AE0Q, Oct 1997 -

This circuit can be used by TR , CT , LOGic-4 , LOG-EQF and other
programs to key the transmitter from an LPT (printer) port while
maintaining electrical isolation between transmitter and computer:

LPT PORT OPTOISOLATOR

                                                       
                        R1  = 1K Ohm, 1/4 Watt
                        C1  = 0.01 Microfarad, 50 Volt

Note: Voltage on transmitter keying line should be kept below
20 volts, and the current should not exceed 100 ma.
MANY other optocouplers will also work.

This circuit can be used by TR and CT (and other logging programs)
to key the transmitter from a SERIAL port while maintaining
electrical isolation between transmitter and computer:

COM PORT OPTOISOLATOR 
                                                
                 D1  = 1N914 or 1N4148
                 R1  = 1K Ohm, 1/4 Watt
                 C1  = 0.01 Microfarad, 50 Volt
                 DTR = Data Terminal Ready

Note: Voltage on transmitter keying line should be kept below
20 volts, and the current should not exceed 100 ma.
MANY other optocouplers will also work.

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