1. pujulde

    Thread Starter Member

    Jul 24, 2013
    95
    1
    I want to make temperature controller using Arduino and the circuit which can simply turn on and off AC bulb within some range of temperatures. As a switch for AC current I want to use moc3021, BC547 and BT136. I use 160 Ohm resistor in collector circuit, 3.3kOhm resistor in base circuit of BC547. From pin 4 of moc3021 to the Gate of BT136 is resistor of 510Ohm. The only difference from the circuit which i used is that I connect A1 of the BT136 to the pin 6 of moc3021 and A2 of BT136 to the AC source. The bulb does not turned on when I give 5v to the base of BC547. When I connect Gate and A2 of BT136 with 10kOhm resistor it turns on. What may be the reason. May the problem is that I did not connect A1 and A2 as it shown in the scheme?
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,510
    2,369
    Take pin 2 of the MOC to 5v common and see if the opto is working OK.
    Max.
     
  3. pujulde

    Thread Starter Member

    Jul 24, 2013
    95
    1
    Pin 2 of MOC is cathode of led, what it gives I do not understand.
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,510
    2,369
    Precisely, so if you take it to common, then the light should turn on, this tests the opto and everything ahead of it.
    Max.
     
  5. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    I would start there myself.
     
  6. pujulde

    Thread Starter Member

    Jul 24, 2013
    95
    1
    Yes, the problem was there. I solder pins as it was in scheme and everything work good.
     
  7. pujulde

    Thread Starter Member

    Jul 24, 2013
    95
    1
    Could you explain the problem, there was not enough current to open the Triac when I connect faulty?
     
  8. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    I believe the issue is when driven that way the gate current has no path to turn the device on.
     
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