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  1. #1
    Ok

    Following on from the thread the other day regarding these inductive proximity switches. And after you have pulled yourselves back together after reading Jonathon build thread which im sure is going to be the topic of this week....

    TL-W5MC1 5mm Inductive Proximity Sensor Detection Switch NPN DC 5-24V | eBay

    Ive got the one on Y working, using the below wiring, however as im running two on the X (for autosquare) Im having problems with interference and I wonder if im missing a diode or something to stop feedback from one to the other?

    essentially, if I wire just one... say just to pin 11 its fine, but as soon as I put two in place (ie to pin 12 aswell) I notice false positives on pin 11 if you follow?

    If I do need a diode? or an additional component id be grateful for a recommendation
    Click image for larger version. 

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  2. Your diagram is wrong... the connection to the bob is from the other side of the load resistor, not gnd.

    But I think you are using these incorrectly. If these are NPN the load resistor is from output to + supply, not output to gnd. And the load resistor needs to be smaller than 100k, exact value depending on whther bob inputs are opto-isolated or not.

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  4. #3
    I found this Click image for larger version. 

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ID:	9903 when I was looking for info on the proximity sensors I've got. Still haven't got around to fitting them though.

    Hope it helps.

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  6. #4
    You might find this interesting:- Three-Wire Sensors
    It explains a little of how they operate ..Clive

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  8. #5
    thankyou all for your posts, I have the sensors working now... and auto-squaring

    :-D

  9. #6
    Quote Originally Posted by kingcreaky View Post
    thankyou all for your posts, I have the sensors working now... and auto-squaring

    :-D
    So what was the problem? Your resistors are 10k, not 100k. I think the sensors you have are not open collector, since they worked without any resistor which implies they have an internal resistor. Putting the 10k resistor from the output signal to ground reduces the output voltage to the 5V required by the breakout board since it forms a potential divider with the other resistor.
    Last edited by Jonathan; 30-08-2013 at 08:02 AM.
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  10. #7
    Yes your right, for a start I got the resistor flavour wrong in my diagram... and I was taking signal from wrong place.

    its now like this... and it works

    (incidently) if you measure across the grey spots, or the green spots you get 4.97v high, and 0.01v low

    Click image for larger version. 

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  11. Whats the supply voltage?

    These are open collector NPN sensors so your BOB must have pullup resistors and the external resistors are not needed.

    Diagram attached shows how to use both PNP and NPN open collector proximity sensors.

    Click image for larger version. 

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    Last edited by irving2008; 30-08-2013 at 11:52 AM.

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  13. I'm starting to look at switch options for my design - are you using these proximity switches for homing?...are they accurate enough on a repeatable basis for that (ie, tool changes, flipping work piece etc)?

  14. #10
    Quote Originally Posted by CraftyGeek View Post
    I'm starting to look at switch options for my design - are you using these proximity switches for homing?...are they accurate enough on a repeatable basis for that (ie, tool changes, flipping work piece etc)?

    In my opinion yes, sheerly because there is no mechanical parts. I cant talk from too much experience with flipping work etc but they were recommended to me by another forum member who does.

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