I am trying to control some 220v devices in my house using Arduino with BT138-600E triacs and MOC3021 optocouplers as shown on the circuit below (please tell me if there is something wrong with circuit).
and I got a couple of questions
1: Where exactly is it unsafe to use a thin 0.5mm jumper ?
2: Does the AC current go through the triac only , or it also goes into the optocoupler ?
3: Do I need a heat sink for the triac ? I saw some projects online in which the triac is on a heat sink.
Thanks in advance 
You're putting 220vac into your breadboard?
- any part of the ac circuit
- part of the ac goes through the opto-triac
- maybe, probably
N.B. - The triac's tab is electrified.
MT2 should go to Line (Live)
The load should be connected to MT1
nope , I am using a pcb prototype like this one
is that unsafe ?
1: so only the red wires ?
2: is the current that goes through the two resistors and the optocoupler large ? are jumpers dangerous to use here (between the optocouplers and the triac)?
also one more question please , what are the appropriate values for the three resistors ?
thanks.
I'll get shot down by some members for saying this, since it's not our place to police what people do in the privacy of their own homes... but here goes:
If you have to ask how to do this mainsy 220VAC stuff, you shouldn't be trying it
When power is applied
Keep one hand behind your back at all times! <<<
Values? The datasheet is a good reference.
See "Figure 8." in the following PDF -- Motorola MOC3021 datasheet pdf
I totally over-rate the components. Resistors, >= 1W, carbon-comp (No inductive), flame-proof better; Capacitors 500WVDC.
US bias here but most of the stuff here that runs on 220VAC does so because of high current draw so my question would be what kind of power dissipation are you anticipating?
Please, please, please, buy a professionally designed solid state relay controller board for this project.
They are not that expensive anymore. Proper packaging and isolation of dangerous circuits is crucial. Leave it to the experts.
The Arduino can safely send logic signals to the properly isolated board.
I understand the sentiment for safety's sake here but how far do we want to undermine the 'do it yourself' spirit? Electronics at the component level gets harder and harder because of miniaturization. Just about everything is unsafe in the wrong hands. That is why I was asking about the load requirements.
I understand the sentiment for safety's sake here but how far do we want to undermine the 'do it yourself' spirit? Electronics at the component level gets harder and harder because of miniaturization. Just about everything is unsafe in the wrong hands.
DC voltages below 40V have never killed anyone.
AC voltages > 100V have killed many.
At the very least use schemes like this: www.instructables.com/id/Yet-Another-Arduino-110v-Power-Controller
The AC power should be controlled inside a sealed, isolated power relay.
There still will be 110 or 220V connections some where. The author enclosed them in a standard power outlet. Not glamorous but reasonably safe. I would also "pot" the electronics. That is cover all connections with a nonconductive adhesive seal in case a power wire ever broke loose.
If the intent is conduct bench experiments then follow my original recommendation and buy a prebuilt control board.
If the intent is to play around with triacs then buy a 110->24V transformer. 24V AC is safe and cheap. These transformers are widely used in household thermostats, etc.
Maybe this is available in 220?
JimboZA:
Maybe this is available in 220?
Base on OEM website, 120V only.
powerswitchtail
outofoptions has the right idea. Notice that the solid state relay is enclosed. The AC and control terminals are well separated with screw terminals. I am not familiar with the particular brand, but this is the sane approach. I would also provide an additional tie down for the AC power wires to ensure they cannot pop loose.
If this becomes a permanent installation, you must install in a suitable box with everything firmly secure.
I know I have been overbearing in this thread, but I dealt with HiVolt AC power in the chemical industry. I learned that precautions are essential when ever you mix low and Hi level voltages.
Yeah, at that price the separate components probably become more expensive than the one unit. I know a lot of guys are using these in home brew setups and not reporting many problems with them. If this is a permanent setup and not a learning exercise then it becomes an easy choice.
Thanks guys , I guess I'll just use a relay seems more safe and I don't think that I need to care about thermal considerations.
We still don't know your load, but the heat sinks for the relay I pictured runs about the same as the relay.
This is super safe and simple as can be and only involves off the shelf equiment (no 220 or 110v wiring is required).
I used a wireless transmittor (no coding required), a high power switch receiver, a 5v relay and an arduino. Works like a clock, and it is SAFE!
Here is how A safe and simple way to switch 220v AC with arduino - YouTube
A safer option (if you still want to proceed).
Use an old power supply and remove the rectifier circuit so you end up with a low voltage AC, use the breadboard and learn to control low voltage AC... a small bulb rated for your supply will allow you to learn safely and when and only when it's working....
Build it, test with low voltage ac... if success wire up the 240v mains to it, hide it away in a non conductive case, stand well back, maybe a prayer (if religious) and throw the power switch lol
hai admin!
my name is Shila.
I have 1 question for you.
why you use arduino instead of raspberry pi to control home appliance?
thank you 
shilafarhah:
why you use arduino instead of raspberry pi to control home appliance?
Because that's what we're all about here.
I think you get that.