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Thread: Proximity sensor

  1. #21
    Senior Member chubbyjp77's Avatar
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    That resistor will work fine for your application. It may even be the same seller I've bought from before.

  2. #22
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    Ok. Resistors ordered. I'll lay the components out on the bench and take a picture before I go hot. Which reminds me... My machines primary power requirement is single phase 220. 3 wires. 2 hot plus ground. (Actually the service is 208v). My circuit requires 120 and I really need it to work with the machine's main power switch. Is there a recommended transformer that can give me 120v plus a neutral from 208v? Most of what I see available is 220v to 110v.

    Pete

  3. #23
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    A transformer will give you an isolated supply, not a neutral unless it's a tapped auto transformer. No problem with that though, the one you mention will give you ~104V. This does, however, mean you know have a supply with no relationship to earth which can get complicated.

  4. #24
    I'm not sure what your local code is. But I've seen setups where one of the lines are used for hot and the Ground as neutral to get 110v from 220v. There has to be a breaker or fuse and a disconnect switch in the 110V side.

  5. #25
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    Well I've finally finished this thing. I still have a few more odds and ends to finish up as far as installation goes, but all of the switching is functional. I initially held off attaching the resistor across the SSR coil and the proximity sensor would not function correctly. The sensor was leaking enough voltage to trigger the SSR so the circuit would not open regardless of the state of the sensor. After double checking all of my wiring I attached the resistor and it worked fine after that.
    I ended up buying a transformer that converts 208v to 120v for $40 on eBay.

    image.jpg

    image.jpg

    Pete

  6. #26
    Peetee looks Good! The 208 to 120 Transformer was a good Idea.

  7. #27
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    Project complete! Works exactly as I hoped.

    Thanks for the invaluable input!

    20171001_183306_resized.jpg

    Pete

  8. #28
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    [safety_bs]
    Not to be a stick in the mud but if this is truly meant to be a "safety" level device, it should be dual channel RF encoded prox and monitored by a safety monitoring relay. I know... blah blah blah, safety Nazi, blah blah.

    I'm only throwing this out there because if you're on the hook for this safety enhancement and it fails to protect whoever, then it's lack of compliance may be a point of contention.

    I guess the work around to compliance is to not identify it as a safety device...lol.

    [/safety_bs]

    Otherwise, nice work..
    FLAME ON...!!!!

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