6n135 Optocoupler 24vac input

Discussion in 'Electronics Resources' started by Tom544, May 4, 2016.

  1. Tom544

    Thread Starter New Member

    Mar 14, 2016
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    0
    #1, I connected the 6n135 optocoupler on my breadboard with 5vdc. pin8 >5v, pin5>GND, pin6>Vo with 1K pullup resistor. Input side pin2 >5v thu 220 ohm current limiting resistor and pin3 > GND. I get 15.9 mA on input side, with output (High in = Low out).

    #2, I kept all the same on output side and connected 24vac (26.2 vac, 37v rms) to pin2 thur 2.2 K resistor and a diode and pin3 to the other side. I get 5.0 mA of current on input and pulsed output.

    #3, I changed the diode from series to parallel across pins 2 & 3. with 2.2 K resistor in series with the 24vac input I get .18 mA on the input and pulsed output.

    #4, I connected 24vdc to pins 2 & 3 with a 2.2k resistor in series and I get 10.1 mA. 24/.01 = 2.4k (ok) The lowest current was 6.5 mA to get a steady output.

    Why am I getting the low current readings on my meter for #2 & 3? Because of the half wave DC input?
    Which is the better way to go for connecting the diode if needed?
    I believe 10-15 mA should be good on the input. The Output will go to an Arduino Uno pin #7 and input will be 24vac from HVAC system when completed.
    Thanks for any help!
    http://www.vishay.com/docs/83604/6n135.pdf
     
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    6,459
    1,274
    If I've understood your circuit description correctly, both #2 and #3 should give much the same results; an average input diode current of about 8mA.
    Here's a simulation:
    Opto-with-AC-input.PNG
    Your low current readings are probably due to your meter not responding correctly to the weird waveform it is seeing.
     
  3. Tom544

    Thread Starter New Member

    Mar 14, 2016
    16
    0
    Alec, I believe the waveform is affecting the meter reading. Which way to connect the diode is the best?
    On your diagram, V1 or V2? or it doesn't matter?
    Thanks!
     
  4. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    6,459
    1,274
    Doesn't matter.
     
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