Hi guys, there is a question i'm always in doubt. Let see if anyone can
make it clearer.

        I always followed the traditional rules as the diagram below taken from
http://www.hut.fi/Misc/Electronics/circuits/parallel_output.html

                                                   V+  (12V)
                                                  |
                                     +------------+
                                     |            +------+
Parallel                            |            |      |
Port                                |    D1     ---     |
                                     |   1N4001  / \    Relay coil
           R1    1  ----------- 5    |          /---\    |
  D(x) ----1k------| Opto-     |-----+            |      |
                   | Isolator  |                  +------+
  GND -------------|           |-+                |
                 2  ----------- 4|                |
                    CNY 17 or    |   R2        | /
                    4N25         |   4.7K    B |/  C   T1
                                 +--\/\/\/\/---|      BC547A or 2N2222A
                                               |\  E
                                               | V
                                                 |
                                           external circuit ground

        But i already saw, and assembled myself a circuit without the
transistor, with the 4N25 being connected directly to the relay and the
diode. Is it right or wrong? What are the implications as both seem to
work well.

        Thanks.

[]s Rafael.

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