Hello
I would like to know how to use the arduino to switch on 220v light bulbs.
I have figured out how to programme the board to simulate what I need with LEDs but how do I get the I/O pins to trigger relays?
Being a total noob in electronics I don’t even know if what I’m asking is really easy or totally impossible.
Hope you can help.
Thomas
using LED’s as the basis of a simulation, you replace the LED’s with any relay that’s suitable for switching via the low voltage arduino, and the higher voltage light bulb. ie. 5v input to 240v output
If your a n00b, I’d advise against playing with 240v/110v.
Yes, but unfortunately the need for the resulting project is greater than my knowledge of electronics i.e. I came to the arduino because I have something I need doing, rather than being someone looking for things to do with the arduino.
I came to the forum because the tutorials assume a level of knowledge higher than I have. For example, I have just discovered that although I was able to program the board to turn on the LEDs correctly, I should have put resistors with the LEDs. Not having any electronics experience I didn’t know that.
Would I need resistors for the relays?
I am not frightened of playing with 220v but could someone tell me if I’m missing more parts in my circuit?
The only thing with relays is they should have a diode across them to prevent ‘miniature surges’ when the relay turns off.
Tip: The red wire does not connect to the black wire. Especially not via a body part. 
If your not afraid of 220v, then I’d definitely advise against it.
As someone who has been shocked a number of times with it, its not something to take lightly.
Although its interesting to note that mains is nothing compared to sticking your finger in a ordinary battery powered camera flash. Now that hurts.
A 350V capacitor discharging instantly in to your finger.
Although its interesting to note that mains is nothing compared to sticking your finger in a ordinary battery powered camera flash. Now that hurts.
A 350V capacitor discharging instantly in to your finger.
;D ;D ;D I did that a couple of months ago while pulling apart my old digi camera, if the shock wasn’t enough I nearly did it twice as the capacitor on those charge unbelievably fast.
Would I need resistors for the relays?
Nope, I’ve just finished soldering up a slim board with a 595, 5 relays, and 5 LEDs across the contacts to get a visual on what the relays are doing - they haven’t blown yet lol if you use resistors the relays won’t work, I found that out by accident when I first starting testing relays.
Oh just a note: Make sure you use relays rated for 240v with enough amps for your purposes.
If you use little hobby 12v relays, the whole thing will probably explode in a shower of sparks.
;D ;D ;D I did that a couple of months ago while pulling apart my old digi camera, if the shock wasn’t enough I nearly did it twice as the capacitor on those charge unbelievably fast.
Well the one I was ripping apart was broken.
I deliberately tried it out one last time to double check that it was in fact dead before opening it up so the capacitor was freshly charged.
Turns out that the bulb was probably dead but the rest of it was working very well.
ummm, sparks! yeah those relays are rated 240v, but I don’t have any plans to go near 240v, nor would I recommend it in fact, even the modtronix ppl have got a giant warning message accompanying their boards, that “are” rated for 240v - these are for 12v wall DC, safe to tongue test ;D