Optically Isolated Phase Controlling Circuit

[aratti]

Try this way it should work.

Than place an oscilloscope on pin 2 of LM555 and you should see a pulse every 8,3 milliseconds (if your main is 60 Hz) or every 10 milliseconds ( if your main is 50 Hz)

Al.

[dhanush]

Try this way it should work.

Than place an oscilloscope on pin 2 of LM555 and you should see a pulse every 8,3 milliseconds (if your main is 60 Hz) or every 10 milliseconds ( if your main is 50 Hz)

Al.

Thank you so much aratti.

Ok I am going to build with your way, but I like know that what are the problems in my circuit, you said H11L1 is on all time, so zero crossing detecter should not work. When I am looking your way, the main differents is you are not avoiding zener diode (D5) and H11L1 parallel resistor (R2) right? On EFY Magazine circuit both components are not using, but that is working circuit. For getting knowlege, can you please explain why zener diode (D5) and resistor (R2) is used in this circuit?

And also please tell me, if I want trigger upto twenty five LM555 for controlling upto 25 fan, which transistor I need to use instead of MPSA40. Is this transistor has enough current to trigger upto 25 LM555?

[aratti]

For getting knowlege, can you please explain why zener diode (D5) and resistor (R2) is used in this circuit?

Detecting the zerocrossing correctly (without delay) is not a simple metter. Here we have got to thrust Fairchild engineers.

When you have got a working circuit, with the proper zerocrossing pulse detected by your oscilloscope, then tray to remove some components you judge useless and see the result on your scope. If pattern doesn't change you were right otherwise you will have to resolder the component in its original position.

This is the best way to learn.

And also please tell me, if I want trigger upto twenty five LM555 for controlling upto 25 fan, which transistor I need to use instead of MPSA40. Is this transistor has enough current to trigger upto 25 LM555?

I don't recommend to use this solution having a long wire connected to pin 2 of LM555 will works as an antenna with unpredictable results.

You should have 25 complete circuits, you can supply the 12 Vac directly to all 25.



Al

[dhanush]

Detecting the zerocrossing correctly (without delay) is not a simple metter. Here we have got to thrust Fairchild engineers.

When you have got a working circuit, with the proper zerocrossing pulse detected by your oscilloscope, then tray to remove some components you judge useless and see the result on your scope. If pattern doesn't change you were right otherwise you will have to resolder the component in its original position.

This is the best way to learn.

Al

I am not trusting EFY Magazine schemetic that why I am using Fairchild schemetic. EFY Mag is Indian edition. I am developing this project is for business purpose, so I need quality product. Good reply and thanks.