How does this work?

Discussion in 'General Electronics Chat' started by NoviceChris, Aug 11, 2018.

  1. NoviceChris

    Thread Starter New Member

    Aug 11, 2018
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    Hello all.

    Can anyone tell me how this works please?
    Please see pic.

    Obviously the red and black is power to the sensor but when the sensor is activated, how does it become an active circuit or switch?
     
  2. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
    7,757
    2,183
    How tall is the large black rectangle in the center of the receiver board? It might be a reed relay, in which case the white and yellow (or green) wires go to a single "Form A" contact set, which is SPST, normally open. The contacts close upon receipt of a valid signal.

    ak
     
  3. NoviceChris

    Thread Starter New Member

    Aug 11, 2018
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    I have put a voltage tester on all cables when active.
    Sensor activated:
    Positive to green = no output
    Positive to white = no output
    Negative to green = no output
    Negative to white = no output
    Green to white = no output

    Sensor in standby:
    Positive to green = no output
    Positive to white = no output
    Negative to green = no output
    Negative to white = no output
    Green to white = no output

    Simple talk please as I don’t know jargon or acronyms

    What I want to achieve is a simple switching function. (Break the sensor = switch on)
     
  4. ericgibbs

    Moderator

    Jan 29, 2010
    7,665
    1,546
    hi Chris,
    There will be no voltage output.
    A pair of contacts are closed when active.
    Do you have a resistance Ohms range on your test meter.??
    E
     
  5. ericgibbs

    Moderator

    Jan 29, 2010
    7,665
    1,546
    hi Chris,
    Try these two circuits.
    One for resistance and one for a voltage output.
    Do the Ohms test first.
    E
     
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  6. NoviceChris

    Thread Starter New Member

    Aug 11, 2018
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    Yes. 2m,20k,200k,>+2k,200?
     
  7. ericgibbs

    Moderator

    Jan 29, 2010
    7,665
    1,546
    hi,
    So when you measure the Ohms and then activate the receiver by pointing the transmitter at it, the contacts should close and the resistance meter reads almost zero Ohms when activated and greater than say 100K Ohms when not activated.
    Can you check that out.?
    E
     
  8. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    7,970
    1,347
    Ensure Jumpers J1, J2, are set the same on both transmitter and receiver,.

    Put jumper onJ3, put power on, measure between Green/White it should read short circuit, when the unit receives a valid code signal, the relay operates and Green/White becomes open circuit .

    Remove J3, and the Green/White are reversed, ( open circuit until a valid code received ).
     
  9. NoviceChris

    Thread Starter New Member

    Aug 11, 2018
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    Ohms read 1 when connected to white and green when transmitter is off (bream is broken) and drops to 0 when transmitter is on (bream is active and connected)
    I’m guessing that means it’s an open circuit when beam is not broken?
     
  10. NoviceChris

    Thread Starter New Member

    Aug 11, 2018
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    I’m sorry I don’t understand the jumper, j1,2,3 stuff? Can you explain so a 5 year old would understand. What is it for?
     
  11. LesJones

    Well-Known Member

    Jan 8, 2017
    2,059
    609
    The jumpers select the frequency that modulates the transmitted infra red signal in the transmitter. In the receiver the jumpers select the centre frequency of the bandpass filter. If the transmitter is set to a different frequency to the receivers filter then it will not be recognised. The option to select different frequencies is so that units working close together do not interfere with each other. Think of it a bit like radio stations transmitting on different frequencies. You only receive the one that your radio receiver is tuned to.

    Les.
     
  12. NoviceChris

    Thread Starter New Member

    Aug 11, 2018
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    The same as using a radio transmitter for an alarm or similar when you select the codes by turning on/off the numbered switches.
    What does nc/no mean?
     
  13. sghioto

    Well-Known Member

    Dec 31, 2017
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    NC means normally closed contact
    NO means normally open contact
    SG
     
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  14. NoviceChris

    Thread Starter New Member

    Aug 11, 2018
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    Great. So I can reverse the circuit if I need to change it to constantly open or constantly closed. Thanks
     
  15. sghioto

    Well-Known Member

    Dec 31, 2017
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    No. When the beam is not broken it's a closed circuit.
    SG
     
  16. sghioto

    Well-Known Member

    Dec 31, 2017
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    Is this the detector you are planning on using for your other thread?
    SG
     
  17. NoviceChris

    Thread Starter New Member

    Aug 11, 2018
    22
    0
    No. This will activate something I built last year.
     
  18. NoviceChris

    Thread Starter New Member

    Aug 11, 2018
    22
    0
    Thanks all. You have been a great help and very welcoming.
     
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