At 11:39 PM 10/6/2005 +0200, you wrote:
>Hello!
>
>I have a IR-sensor with an open collector output.
>Can somebody be kind and explain how it works
>or show me with a drawing will be nice!

It would be better if you could post a link to a datasheet.

"Usually" industrial sensors with open-collector outputs have an NPN
transistor with emitter common with the (-) supply. So, you'd typically
use a pullup resistor somewhere in the circuit, or use a PLC input which
has it built-in.

In some very benign situations (short wires, all inside one enclosure,
little electrical noise) you might be able to go directly into a
PIC port pin and omit the signal conditioning and isolation, but that's
oh so seldom true in industrial situations.

(view with fixed-width font)

          +12V or whatever rated supply voltage

                 o                       VCC
                 |                        +
                 |                        |
                 |             pullup     |
                 |   Sensor           \  .-.
               .-------------------.     | |   optional isolation and
               |                   |     | |    Signal conditioning
               |                   |     '-'       .----------.
               |                   |      |        |          |
               |               +----------+--------|          |-----o
               |               |   |<- "open       |          | logic
               |      ___    |/    |  collector"   |          |  level
               |    -|___|---|     |               |          |
               |             |>    |               |          |
               |               |   |               |          |
               |               |   |               |          |
               '-------------------'               '---.------'
                               |                       |
                              ===                     ===
                              GND                     GND


Your sensor should come with specs that spell out the range of supply
voltage it expects & the current and voltage rating of the output.


Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
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