Optically Isolated Phase Controlling Circuit

[dhanush]

I got a schemetic from fairchild for Optically Isolated Phase Controlling. I modified a little bit on that schemetic before the Optoisolator. Please check my schemetic and reply any problem on my modified schemetic.

I attached both schemetic, one is from fairchild and the other one I modified.

[Melanie]

In your version, what is the point of the H11L1 opto?

[dhanush]

In your version, what is the point of the H11L1 opto?

I cant understant what u r asking. Point means? Please explain your question.

I am going to develop this circuit for fan regulator and it is not for one, i want to attach upto 25 fan regulator by adding same circuit (after optoisolator) again. So i am scare about lightning, thats why i am using optoisolator with transformer (not directly connect to main supply). This project is developing for large office purpuse.

And please mention, what transistor I need to use for trigering upto 25 LM555 IC, instead of MPSA40. Is MPSA40 have enough current for trigger pin of LM555, if I attach 25 LM555. I am not an expert please help.

[aratti]

In the first schematic H11L1 trigger LM555 at every zero crossing, in the second schematic H11L1 is on all the time (so it is useless). Second schematic will not work!

Zero crossing happens when the sin wave of your main, cross the zero line.

Al.

[dhanush]

In the first schematic H11L1 trigger LM555 at every zero crossing, in the second schematic H11L1 is on all the time (so it is useless). Second schematic will not work!

Zero crossing happens when the sin wave of your main, cross the zero line.

Al.

What is the problem on second schemetic? Please resolve the problem on second schemetic, I dont need to connect directly on main, I need to connect via transformer, please help me.

I have an another circuit that was published on EFY Magazine, that circuit is connected via transformer, I will give you that pdf link http://www.electronicsforu.com/EFYLi...-01_July06.pdf and recorrect my error on second schemetic. I need to work second schemetic same like newly given schemetic. Please resolve it.

Thanks for reporting the error.

[Melanie]

Actually my point was that in the first schematic the H11L1 is providing isolation from the supply to the 555, in the second it is provided by the Transformer - which makes it kind of pointless having it still in circuit. Also that Transformer is 12-0-12... is there a reason you want to run your Trigger circuit at 24v?

Blindly copying other peoples schematics is one thing... but modifying them without actually knowing what they do is another (kinda like all the cut & paste that goes on in this forum I suppose)...