Switch fluorescent tube lights with MC3041 / BT136

[t0m]

I want to switch my basement lights (2x40W tubes @ 110V) and have selected a MOC3041 optocoupled triac driver and BT136 sensitive gate triac. The schematic I am looking at is Figure 13 on https://www.futurlec.com/LED/MOC3041.shtml. It specifies 360R resistor in series with the load and 330R between the gate and one terminal of the triac, for use with 240VAC mains. What resistor values should I use? I presume that lower values are needed but I don't know how to select them.

 

[ZASto]

You have everything written/shown on page 5 of the datasheet (Figure 13). Try to read all of the pages, not only a tiny bit.

 

[t0m]

I'm not finding that a helpful comment. Obviously I have tried to read the rest of the datasheet for the MOC3041, and the datasheet for the triac, but I am not sure what the dependencies are.

 

[kam1787]

except for Rin, use the resistor values from figure 12

 

[dc740]

Hello. I'm new here. The standard suggested circuit seems to have a few problems with CFLs. I implemented it, and when the light is turned off, it randomly "flashes" for a fraction of a second.

From what I could understand, this is caused by the cfl low consumption. One of the fixes was to make it consume more. And I would like to know if a different circuit, like this one I found googling could fix the problem.



I'm not an expert in electronics. I'm teaching myself, so this kind of edge case problems present a big challenge, even when they could be easily fixed by an experienced user.

 

[ZASto]

Take out the snubber (C3 and R4). The electrolytic capacitors in CFL can receive enough charge for flashes that you observed.

 

[dc740]

Take out the snubber (C3 and R4). The electrolytic capacitors in CFL can receive enough charge for flashes that you observed.

Thank you SO MUCH. I can confirm that the basic circuit (the one from the datasheet, and the original post) works fine without the snubber. The only CFL that had problems is working now (it depended on the brand and consumption).


THANK YOU

 

[dc740]

Well, not everything that shines is a properly working light... The circuit works fine, unless the temperature is low (like every morning at home). From what I understand, the triac needs more current to turn on. Do I need the diodes like the ones from the schematic I posted before to add a transistor? (is it safe?). I was planning to add an NPN transistor between the moc3041 and the gate, to increase the current. Is this correct? Am I doing something terribly wrong?

 

[ZASto]

When the temperature is low, you have a problem with your CFL, not with your circuit. There is nothing that you can do. In one cold storage room, ordinary incandescent bulbs were replaced with CFL lamps and they do not produce enough light when temperature is below 4 degrees C

 

[dc740]

When the temperature is low, you have a problem with your CFL, not with your circuit. There is nothing that you can do. In one cold storage room, ordinary incandescent bulbs were replaced with CFL lamps and they do not produce enough light when temperature is below 4 degrees C

That is very disappointing. I thought it was a problem in the circuit because my night lamp works fine in the same room. I'm talking about my bedroom and it only happens in the mornings.

Well, thanks anyway! I'll try with a different cfl until I get my heater fixed

 

[dc740]

UPDATE:
I don't want to look ungrateful, but I think there is another problem with the circuit, and not the CFL itself. I replaced the circuit with a pc817, a transistor and a relay, and now it works fine in the morning. The important part is that I only desoldered the triac+resistances from the board and soldered the relay+transistor+resistance. The lights and switchs are all the same. I didn't change any of that. If the cold temperatures (never below 10ºC) are preventing the CFL from turning off while using the triac, why does it turn on when the control is a relay?

Thanks