Can you put up a small sketch of what your setup looks like? It's a little hard to figure it out in text.
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Can you put up a small sketch of what your setup looks like? It's a little hard to figure it out in text.
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Ive attached a basic diagram of the circuit. Everything on the left side of the line is the controller and everything on the right represents the seperate lights being controlled. The triacs are inside the light holders themselves. I have shown seperate AC inputs where things are plugged into seperate mains sockets. All of the mains sockets are in the same room on the same ringmain and are seperated by only a few metres of wire.
Note: I dont have the symbol for a triac in this software so pretend the MOSFETs are triacs.
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I would remove the diodes from the inputs of the optos. Reason : when you turn off the drive to the opto from the pic, the input of the opto is now able to take in mains pickup due to the long wire run. This will cause it to trigger falsely. Give it a try. No diode.
Other than that, I see no reason why your circuit will not work. I hope I'm not wrong
Regards
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Im not having any trouble with false firing. This is the first time ive used the diodes in this kind of circuit. They are there to protect the optos incase the wires are connected incorrectly.
If you cant see any other problems with it then ill assume i have a short or dry joint somewhere or the program isnt right. Ill have a look at them in a lot more detail. Thanks for your help.
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With a 1K resistor in series with the pic output, I dont think you would damage the opto LED even if connected reverse. I'm not saying removing the diodes is a solution, just that I think they are redundant.Originally Posted by The Master
Anand
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I thought that too. In previous circuits that use optos i once connected one the wrong way and it never worked after i corrected it. I dont know for sure that the reverse current caused it as i had never turned it on before wriring it the wrong way. It could easily have been damaged by overheating during soldering or it might have been a bad component when it arrived.
The triacs/optos are inside the light holders and its very fiddly to replace them. I have thousands of diodes laying around and they cost almost nothing so its well worth including them just incase.
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Hi,
Figuring you have a MOC3020 opto-coupler the maximum reverse voltage according to the datasheet is 3V so it's possible it got damaged by connecting them backwards. But instead of having the diode in series like you have it now place it anti-parallell with the opto-coupler LED. Then it will clamp the reverse voltage to ~0.7V and the series resistor will limit the current.
As you have it now..... Figuring 5V output from the PIC, 0.7V drop across your series diode, 1.15V drop across the LED we have 5-0.7-1.15=3.25V left across the 1k resistor. This yields a forward current thru the LED of 3.25mA. Although this should work as long as the "firing pulse" thru the LED is at least ~6us or so it just "feels" a bit low to me. Why not simply try with a 330ohm resistor or something?
Now, if you have another optocoupler then obviosuly the above numbers may not be correct but it might be worth looking into it for your particular device then.
/Henrik.
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