Thanks.

My motiv is to detect if the circuit is in close or open state. The idea is to use the NC relay connected to the 220V and the drive the 5V to the Arduino when the current is flowing.

I did try to look for such relays with coil voltage 220v, but couldn't find. Please do provide me a link if you know one.

Thanks.

Can a relay also work the other way around, like high voltage circuit driving a low voltage circuit? If so, please provide me a link to such a product.

Thanks. I see that these contactors ( with 4 pins) are very expensive. Are there any other cheaper alternatives?

Can a relay also work the other way around, like high voltage circuit driving a low voltage circuit? If so, please provide me a link to such a product.

I don't have an idea on the switch with 4 pins. I understand that the switch comes with two pairs of contacts. One pair of contacts is connected to a 230V supply while the other pair of contacts is connected to a 5V supply.

The 230V supply is used to control the lamp using the NC Relay when the arduino is switched off.

When the arduino is powered on, the 5V supply reports the position of the switch to the Arduino from where the actions over the lamp are controlled.

Am I correct?

@veseo

Thanks. I had drawn a circuit diagram at a high level, just to let you know what I understood. Please let me if I got you right. I had attached the circuit diagram.

The problem I see in this circuit is that the switches wont perform until the Arduino switches itself off. In other words, if the light is switched on from arduino, the light can not be switched off from the switch.

@Torremolinos

Thanks for the reply. I did go through your project, but couldn't really find anything related to controlling and monitoring the current status of the light in existing 2-way switch circuits. Please provide me a link or additional info, if I did miss on something.

@Napoli

Thanks. The NC Relay looks as an interesting option, but still not sure if it could be applied to the 2-way or 3-way switch circuits for controlling and monitoring the status of the circuit.

I'm sorry, I couldn't exactly get the circuit diagram you explained. Would be great if you can help me with some visuals.

From what I understood: in addition to the traditional light-switch circuit, one terminal of the switch is connected to the arduino and the other is connected to the NC relay. Please do let me know if my understanding is correct, before I go further on this.

Thanks, your info seems to be helpful. Tried to do some google on optoisolators but couldn't figure out the exact purpose and how they could be used in the current situation I think the stuff is getting complex for me to handle. Will have to do some background study on the suggested options.

My first impression was that optoisolators act more like a fuse breaking the circuit on detecting additional voltages, but wasn't sure how it could be used in conjunction with by the arduino to track if the device is powered on. Any links for reference would be helpful. Correct me if I'm wrong.

Hope the optoisolator idea works for you. Keep me posted.

Thanks, that was informative. I studied on the SPDT and DPDT and will have to do some more study to understand them completely. Most importantly, I'm able to get an idea over the final circuit.

One more question that popped up, let's consider that 2-way switch is implemented with one switch controlled by Arduino and SPDT relay. I understand that the state of the light could be toggled using any of the switches. Would it be possible to read the current status of the light? The whole idea is to figure out if the light is on or off from a remote location and this helps me to toggle the current state or not. Hope I'm not missing something really basic.

Thanks. That sounds interesting. I just read about SPDT latching relays. It was very helpful. I was searching for some stuff related to latched SPDT relays with arduino but couldn't find any. Please do let me know of any useful resources in this direction.

From what I understand, the following two options are available:

• Replace one of the switches in 2-way switch by the SPDT latched relay controlled by arduino
• Add SPDT latched relay controlled by arduino to the existing 2-way switch ending up 3-way switch

Please do let me know if I  understood right.

I am from India and power is supplied at 220V. There are only two-way switches.

Thanks.

Thanks.

I definitely see x10 as an option. I'm interested to know if the arduino connected with the relay module could be used, so that I keep my existing switches intact and would cost me less.

Hello,

I am having two way switches in my room. I am a newbie planning to do some home automation using Arduino and got a few questions in this directions.

--> I am interested to keep the existing AC circuit intact. Would it be possible to add the arduino controlled output into the existing circuit making it a 3-way switch?

Please do let me know of any other alternative approaches if the proposed approach doesn't work.

The overall idea is to have my existing two way switches intact and add an additional switch thats controlled by Arduino enabling home automation.

Any help is appreciated. Thanks.