Quadrature encoding screened lead

Discussion in 'Embedded Systems and Microcontrollers' started by camerart, May 3, 2016.

  1. camerart

    Thread Starter Active Member

    Feb 25, 2013
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    Hi,
    I'm using quadrature encoding on a project I'm working on. I think it is better to use screened lead for the signals, and have been testing using good quality stereo cable, which is quite stiff. I would prefer more flexible lead if possible as it needs to coil a little. Does anyone have any suggestions for what would be the most flexible type of lead for my purpose, please? It also needs a small 5v power wire, plus gnd. (Can the screened earth be also used for power?) All less than 1Mtr.
    Camerart.
     
  2. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,696
    904
    Check out headphone wire.

    John
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
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    No you should not use the Shield/Screen for power.
    Particularly if using single ended output and not using differential output, is it a noisy environment?
    Max.
     
  4. camerart

    Thread Starter Active Member

    Feb 25, 2013
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    30
    Ok, John
    Hi M.
    What is single ended and differential output?
    I have the ground connected only at the circuit end.
    Noisy? The motors are switching and commutating, and there are transmitter/receivers all withing 1/2 Mtr.
    Is Joh's suggestion of headphone wire ok?
    C.
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Encoders often do not act alone but in an otherwise electrically noisy environment as in CNC machine etc, so it is important to prevent noise appearing in the signal in this case a differential output such as RS485 driver is used, for short distances you can get away with single ended. But should still important for shielding. See maxim MAX9112
    Could be overkill maybe in your case, but I use individual shielded pairs with OA braid shield.
    Max.
     
    Last edited: May 3, 2016
  6. camerart

    Thread Starter Active Member

    Feb 25, 2013
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    Ok, thanks.
    C.
     
  7. BR-549

    Well-Known Member

    Sep 22, 2013
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    Pardon my ignorance guys. Googled the term with no luck.

    What is a screened lead?
     
  8. camerart

    Thread Starter Active Member

    Feb 25, 2013
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    Hi B,
    The insulated +v wires in screened lead are covered by braiding, which is the Gnd side, instead of two parallel wires. Used in earphone, microphone, USB, signal cables to stop interference getting into the signal.
    C.
     
  9. BR-549

    Well-Known Member

    Sep 22, 2013
    1,998
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    Still have no idea. You said it was stiff. Could you possibly mean coax cable?

    What term do you use, when you search for this product on google?

    All I get is screening for lead poisoning.
     
  10. recklessrog

    Member

    May 23, 2013
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  11. MaxHeadRoom

    Expert

    Jul 18, 2013
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    The encoder cable I use is actually intended for Data transmission and it has each pair shielded by foil shield and has an overall braid shield.
    It also has one pair one gauge up from the rest for the power.
    But this is used in a noisy industrial environment.
    NOT cheap though.:(
    Max.
     
  12. camerart

    Thread Starter Active Member

    Feb 25, 2013
    517
    30
    Hi,
    I looked in my old cable box and found some quality Phono cable with four individually screened cables, and it is remarkably flexible too. I'll use that.
    Thanks to everyone.
    C,
     
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