TRIAC light switching.

Hi. Would it be possible to use **broken link removed** (or any other suggestions) TRIAC to switch 40W bulbs connected to a 240V power supply using a 5v signal? (Arduino Microcontroller)
I am unaware of exactly how triacs function and know only that i want to simply be able to control my bulbs using my computer. I have tried relays but they are noisy and suffer from that irritating EMF kickback. ANy help would be very much appreciated.
Danny.

You should probably move this to the microcontroller forum but this will get you started:
**broken link removed**. One thing I didn't see in this application note was any mention of the use of optocouplers which some consider good design practice with triacs.

See this circuit... You can connect your 40w bulb instead of motor in this circuit... Hope it ll usefull to you...

please post the circuit

The circuit doesnt exist.This is the problem. I am very new to this. I have successfully managed to control the lights with relays and the circuit consists simply of connecting the coil of the relay to the arduino to control the mains supply across it.
I assume that triacs work on a similar principle to transistors, the problem i am facing is that i do not understand the documentation which comes with the triacs so i dont know if it will suit my needs. hope that makes sense.
Dan.

https://www.edaboard.com/threads/39612/
https://www.edaboard.com/threads/84254/
see these

Senthilkumar_rjpm said:

See this circuit... You can connect your 40w bulb instead of motor in this circuit... Hope it ll usefull to you...

Click to expand...

Sorry... It is good to use an optoisolator (with triac as ouptut) but in this circuit from where the gate of the main triac can get its driving current?

Kerim

Edited:
I mean let us make a short on the output of the optoisolator... what could happen? Nothing I guess :wink:

---------- Post added at 19:55 ---------- Previous post was at 19:43 ----------

gonadgranny said:

Hi. Would it be possible to use **broken link removed** (or any other suggestions) TRIAC to switch 40W bulbs connected to a 240V power supply using a 5v signal? (Arduino Microcontroller)
I am unaware of exactly how triacs function and know only that i want to simply be able to control my bulbs using my computer. I have tried relays but they are noisy and suffer from that irritating EMF kickback. ANy help would be very much appreciated.
Danny.

Click to expand...

The main advantage of relay is its electrical isolation. So your PC is safe when using it.
About triacs, a good circuit using an optoisolator is already posted. Unfortunately it has now a minor mistake (in one connection)... I believe soon it will be corrected and your problem be solved... the driving circuit is also explained in the datasheets of the MOC series.

Kerim

Edited:
6-Pin DIP Zero-Cross Optoisolators Triac Driver Output
MOC3041M, MOC3042M or MOC3043M
They differ only in their input sensitivity (15, 10 and 5mA)
All these 3 ICs are made for 400V peak (good for 220Vac)

Correcting the error on the posted schematic:
The resistor which is between the opto output and the A1 (lower terminal of the main triac) should be connected instead to A2 (upper terminal of the triac). The value of this resistor (which limits the current in the opto triac output) could be 390 ohms.
In case of small triacs (<10A), it is also better to add a resistor (say 330 ohms) between the triac gate and A1 (equivalent to cathode for thyristors).