how can I determine the pins of an optical encoder

Discussion in 'General Electronics Chat' started by the lord of tea, Jan 30, 2010.

  1. the lord of tea

    Thread Starter New Member

    Dec 25, 2009
    4
    0
    hi every body

    I'm using optical encoder to take feedback signal from DC motor and control its speed .

    the problem that I face is how to determine the legs of the optical encoder which one is the Vcc, ground and the channel ..??

    my optical encoder is three pins encoder as in the following photo:

    [​IMG]

    I hope that if any one knows an efficient way to determine each leg tells me..

    thanks

    the lord of tea
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Is that an encoder, or an optointerrupter, with an emitter (IRLED) on one side and a receiver (phototransistor) on the other? Your photo is a bit blurry.

    One good way to tell what is is is to use Google to look up the device number and obtain a data sheet.
     
  3. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    Use a multimeter set to diode setting.

    The LED is easiest to identify first, it should have a forward voltage drop of about 1.3v, some higher maybe 1.6v.

    Once you have identified the LED you connect a 5v supply to the LED through a small series resistor, 1k is fine.

    Then connect another 1k resistor (any value 1k to 10k will do) to the remaining pin of the 3 pins, and the other side of that resistor to 5v. Generally they are common ground on the centre pin which is the LED cathode (LED - pin).

    That should be enough to get it working. When you put a bit of card between the sensors the voltage on that last pin should go from 0v up to about 5v.
     
  4. the lord of tea

    Thread Starter New Member

    Dec 25, 2009
    4
    0
    you are right its an optointerrupter, but google does not benefit me so much ..
     
  5. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    Do you have a part number so that we can try to find the datasheet?

    hgmjr
     
  6. the lord of tea

    Thread Starter New Member

    Dec 25, 2009
    4
    0

    I tried that ..

    I think I'll repeat that tomorrow in the university using osc.

    one method that I found is using the multimeter (putting it on buzzer) and try every two pins during this you use a digital camera to notify the IR beam between the transmitter and the receiver ...

    what do you think???
     
  7. SRH

    New Member

    Jan 30, 2010
    4
    0
    Do you have access to an oscilloscope? This makes it all much easier, especially if your encoder has detents.
     
  8. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    You need 2 resistors and a soldering iron, and 5v supply and a multimeter. I do this often and it only takes a few minutes. Please read my post #3 again for the procedure.

    Remeber on the 3 pin ones the centre pin is always the common.
     
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