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AC powered OR gate??

Discussion in 'Electronic Design' started by Jim Thompson, Nov 1, 2004.

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  1. Jim Thompson

    Jim Thompson Guest

    Use a relay on each "sensor" output... parallel the poles to get the
    "OR" function.

    ...Jim Thompson
  2. Alex C

    Alex C Guest


    I have a load, which is a lamp of 240V and 50W, I need 2 sensor to drive it.
    Both sensors are 240V powered and output is 240V.
    How do I create an OR gate for this AC driven device so that if any one of
    the sensor is triggered, the lamp will light up? I can't join both output
    together as it will blown by the back fire if one output is high (240V) and
    the other is OFF.

    Appreciate if you could send your suggestion to as I
    seldom have access to newsgroup..thanks
  3. Jim Thompson

    Jim Thompson Guest


    You need to tell us more about your "sensor".

    ...Jim Thompson
  4. Alex C

    Alex C Guest

    pardon me for my ignorant... there is 240V powered solenoid relay in
    electronics shop? oh... all along I've using only up to 24V solenoid

    ok, will try the suggested method

    thanks Jim!
  5. Alex C

    Alex C Guest

    another question, do I need to put a rectifier across the terminal as in DC
    operated relays to absorb the high current dischage when the relay is switch
  6. Tim Wescott

    Tim Wescott Guest


    That depends on what shop you frequent. There are 240V AC relays
    available from industrial suppliers. In the US I'd look at Granger or
    possibly McMaster-Carr.
  7. Tam/WB2TT

    Tam/WB2TT Guest

    What does OFF mean? Is it an open circuit, or is it switched to the other
    side of the line?

  8. Joerg

    Joerg Guest

    Hi Alex,
    If everything you use including the relays is made for 240V AC then you
    don't need any rectifiers. 240V AC relays should be easily found at a
    larger electrician's supply house. At Digikey you can mail order 240V AC

    Regards, Joerg
  9. Alex C

    Alex C Guest

    I'm not sure what if the state of the output from the sensor when it's
    "OFF" could be floating.
  10. N. Thornton

    N. Thornton Guest

    Or you can just connect them both together, having _ensured_ you got
    the polarity right.

  11. Tam/WB2TT

    Tam/WB2TT Guest

    If the OFF sensor is floating, you should be able connect the two sensor
    outputs in parallel, provided they are on the same phase.NT mentioned that
    also. There is also the chicken's way. Connect a diode from each of the
    sensors to a common power resistor connected to a 48V DC relay. You might
    need a small (~1 ufd) capacitor to keep the relay from chattering. A third
    diode goes across the field of the relay.

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