I am trying to make this circuit:

MOC3041 typical SSR circuit

I got reference from this site, which is very useful, thanking them for info; https://components101.com/ics/moc3041-zero-cross-triac-driven-optoisolator

Despite all of this, I am facing an issue, when I applied voltage (for testing I used stepped down 7.5 VAC) and checked output across load, when snubber is not attached TRIAC is turning off, but when snubber is applied, TRIAC never turns off.

I tested snubber resistor and capacitor with meter, capacitor is not shorted, and resistor value is coming correct. So can I say, snubber components are not faulty as per multimeter. If they are not faulty, why is triac not turning off at all.

Please let me know what is wrong in this circuit, if more information is need let me know.

Note that I have used BTA16A, and instead of 39 Ω of snubber, I have used 360 Ω for inductive load. (360 is not exact value, I have used, 330+39 Ω = 369 Ω since 360 Ω is not a standard value).

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    \$\begingroup\$ 104 is 100nF, not 10nF. Try 10nF. \$\endgroup\$ Sep 18, 2023 at 4:59
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    \$\begingroup\$ What is your load? The snubber will conduct some current, so if your load is not low enough the triac will appear to be on. Also your voltage may be too low to get enough gate current to trigger the triac. \$\endgroup\$ Sep 18, 2023 at 5:26
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    \$\begingroup\$ Well, there's your problem. Give it a decently low resistance load that will conduct more current than the triac holding current. \$\endgroup\$ Sep 18, 2023 at 5:39
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    \$\begingroup\$ Take your voltage, divide it by the maximum holding current in the triac datasheet and make it significantly less (maybe 1/3) of that. Check the power dissipation. This is important stuff to understand so it's better you do it. \$\endgroup\$ Sep 18, 2023 at 6:11
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    \$\begingroup\$ Hello @SpehroPefhany, will be trying that, but it will take some time, since I have removed cap, I will buy new one to attach. as per your suggestion, my voltage is 7.5V /500mA, my triac is BTA16, and holding current is 50mA, so I can use load resistor to be 65ohm or 51ohm that will give about 100ma to 150ma, and I think that will suffice. \$\endgroup\$ Sep 18, 2023 at 6:23

1 Answer 1


It was bit late I got my required components, it is working as suggested by @Spehro Pefhany, there was no load attached so was causing problem I mentioned.

I thank @Spehro Pefhany for his quick response and thankful for his suggestions which worked well for me.

  • \$\begingroup\$ Can you please describe how you solved the problem? \$\endgroup\$
    – Voltage Spike
    Sep 27, 2023 at 15:38
  • \$\begingroup\$ Nothing just attached some load, that is a bulb for my case, one can attach a fan or any load which is handy. \$\endgroup\$ Oct 13, 2023 at 6:30

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