Hi all
I have finally entered in the wonderful world of Arduino, yet as hobbyist I encounter many problems to fully understand what I'm doing or what actually to do.
My current project involves using Arduino to drive some cooling fans (DC) and light bulbs (AC).
Entering more in detail, via a sensor LM35DZ I can detect the temperature and trigger the fan on/off using a mosfet IRF540.
In the test project I use a 12v 400mA power supply, which is connected to the positive red wire of the tested fan(the specific are unknown since the piece of paper talking about them is torn). The fan black wire enters the positive mosfet pin (and it is also connected to the DC power supply positive through a diode 1N4001). The mosfet negative pin is then connected to power supply negative and also to Arduino GND. Pin 0 is connected to the gate of the mosfet via 1kOhm resistor. I enclose Fritzing diagram for further clarification.
So far so good, I got everything working right. The problem is when I try to turn on/off a light bulb, again using Arduino (be careful, I do not care about dimming, only a simple ON / OFF). Well, actually there are 4 light bulbs (for a total of about 100W, using 230VAC).
I have purchased a triac, BTA16-600BRG, and an optocoupler, MOC3062. What I need to do is to turn on lights once a day, let them on several hours, then turn off and wait for the same cicle the day after to repeat. The programming is not a problem, at least not now.
Those are the questions for that I'm asking an answer to you at the moment (plus every comment/advice):
1 - A SSR is formed by a triac + optocoupler (and I own them at the moment) plus other circuits which I ignore the purpose. I have seen circuits with resistors placed between the MOC and the triac, some others have Wheatstone bridges, others have a snubber in parallel with the triac. I would like to "create" a ssr using the components I have; do I really need also the snubber/bridge/whatever, or is it just good using opto triac (and the appropriate resistors)?
2 - In this particular case, is more appropriate to use a pre-built SSR? Or the "diy" ssr is good enough?
3 - If want to build a PCB for the circuit, would be a good thing to separate the DC section from that AC, making 2 separate PCBs?
Talking about PCB, would you recommend to buy/build a PCB to house all of the components? Or you can use a stripboard or even a breadboard? The idea would be to buy a brand new ATMega and to re-build Arduino ad hoc, just to fit the purpose it is used for.
But I think that talking about how to assemble a custom, simplified Arduino made to do just one task might deserve a new thread, other than searching informations about it first.
Links regarding the sources I consulted (or images of patterns that made me wonder)
http://www.signindustry.com/electric/articles/2000-11_ALDORtriacexplainted.php3
Links regarding the components used by me
http://www.datasheetcatalog.org/datasheet/fairchild/MOC3062-M.pdf
I hope everything is clear, since english is not my original language, and that this is the right section 
Siberio