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I have used the circuit from Datasheet of MOC3083 directly. Problem is triac does not fire. 0.1uF cap is MPF and all the values given in data sheet are used as they are. I am using a 100W incandescent Bulb as load. I have connected 2 AA batteries as input to phototriac. Just Change the Phototriac to MOC3083

All the resistors are 1/4 watt standard. This is my first shot at triacs kindly help.

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    \$\begingroup\$ That looks like a circuit for a MOC3041 not a 3083. Also what is Rin and what AC supply are you using? \$\endgroup\$
    – Andy aka
    Sep 21, 2015 at 11:36
  • \$\begingroup\$ I AM USING MAINS 220V Rin is 470E but i have used 1.5KE as well. But I have used MOC3083 as could not find MOC3041 here locally. \$\endgroup\$ Sep 21, 2015 at 11:42

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The trigger current required to cause the output of the MOC3083 to work is 5mA according to the data sheet. You are using two AA batteries giving a voltage of 3V (I assume). The forward volt drop of the LED is 1.5 volts therefore, with a 470 ohm resistor, the current you are injecting into the LED is 3.2 mA and lower than the 5mA recommended. I'm not saying this is the cause but a possible cause.

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  • \$\begingroup\$ I switched it to 1.5K as well but, it did not work. Should I use a 9V battery instead. \$\endgroup\$ Sep 21, 2015 at 11:51
  • \$\begingroup\$ 1k5 will be even smaller current. You need to ensure that at least 5mA flows. \$\endgroup\$
    – Andy aka
    Sep 21, 2015 at 11:51
  • \$\begingroup\$ How about a 9v battery? or 5V DC supply \$\endgroup\$ Sep 21, 2015 at 11:53
  • \$\begingroup\$ With the appropriate value resistor yes. \$\endgroup\$
    – Andy aka
    Sep 21, 2015 at 11:54
  • \$\begingroup\$ Is firing of triac dependent on Load values. I would say "no" but, still want to ask. What should be appropriate resistor for 5V dc supply? \$\endgroup\$ Sep 21, 2015 at 11:57
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You need signal voltage to trigger the MOC, not 220 V. It may be the possible cause of not working.

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    \$\begingroup\$ Welcome to EE.SE, Ojo. Did you notice that Andy's answer was accepted as correct fou years ago? \$\endgroup\$
    – Transistor
    Jan 17, 2020 at 23:57

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