Circuit to connect SEGA 3D glasses to RS-232 port.
--------------------------------------------------

       RS-232
     DB25 / DB9
                                                   10K
RTS   4      7  Switching signal +/- 10V  --------vvvvv--+
                                                         |
                                                         |
GND   7      5  Ground ----+-------------+--+---------+--|----+
                           |             |  |         |  |    |
                           |             |  +-|>|--+  |  |    |
                           +--|>|--+    ---        |  |  |    |  Transistor
                                   |    ---  22 uF |  |  |    |   2N2222
                                   |     |         |  |  |  +-+---------+
                                   |     |         |  |  |  | Emitter   |
                                   |     |         |  |  |  |           |
DTR  20      4  Vdd +10V --|>|-----+-----+         +--|--+--+ Base      |
                                         |            |     |           |
                              +--+--+--+-+-vvvvv---+--|-----+ Collector |
                              |  |  |  |    10K    |  |     |           |
                              |  |  |  |           |  |     +-----------+
                      +-------+--+--+--+-----------+--+--+
                      |       1  9  13 14          5  7  |
                      |                                  |
                      |   RCA CD 4030 Quad XOR gate      |
                      |                                  |
                      | 2 11  12       3  6  8   10   4  |
                      +-+--+---+-------+--+--+----+---+--+
                        |  |   |       |  |  |    |   |
                        +--+   |       +--+--+    |   +--- Outside of jack
                           |   |             |    |
                           |   +-vvvvv-+     |    +------- Middle of jack
                           |      22K  |     |
                           |           |     +------------ Centre of jack
                           +-vvvvv-----+     |
                              22K      |     |
                                      ---    |
                              .01 uF  ---    |
                                       |     |
                                       +-----+

Diode:     --|>|--

Resistor:  --vvvvv--

Capacitor:   |
            ---
            ---
             |

This is my best attempt at a rendition of the circuit which connects my
SEGA glasses to my AT. I didn't design the circuit -- I'm a software
rather than hardware person. In fact I barely understand it -- as far as
I can tell, the .01uF capacitor & the 22K resistors act as a delay. The
outputs of the XOR gates feed back into their own inputs, thus producing
an oscillator. The "jack" mentioned in the diagram is the mini-jack
which is connected as standard to the glasses. "Centre", "middle", and
"outside" relate to the external connections, looking at the thing
end-on.

Disclaimer: The circuit diagram above may be entirely wrong. My
description may be wrong.

Caveat emptor... to paraphrase the standard software licence agreement:
It's as good as I can get it. If it doesn't work or blows up your
computer or your glasses and blinds you for life, I'll give you back all
the money you paid me.

Good Luck...    Frank.