Home automation - Controlling lights


I’m trying to build my own domotics system and I have all the ideas but maybe with some input from you guys I can get around some problems
with an easier solution.

For example, I want to control the lights, so I have a relay module, but I still want to control the lights with a normal switch.
So I make use of the NC and NO ports of the relays to create an electric circuit with an SPDT switch. (I don’t know the name of the type of circuit in english, in dutch it’s called a “hotelschakeling” or hotel circuit)

So this way I can change the switch and the relay and my light will go on and off.

The problem with this solution is that I can’t know if the light is on or off. With a light sensor I can know it but my mainboard is in another room and to buy a mainboard with an xbee adapter and xbee and powersuply module would be too expensive just for this.
So I went with another solution, the Current Module. So I just put it on the electrical thread and I can read if there is current going through.

But a friend of mine, he’s studying electronics engineer so he’s good with electronics, he said to me that I could easily do it with a light sensor, but I just don’t know how to pull this of with the Gadgeteer modules.

Any hints.

/* EDIT */
I didn’t state that I’m just using gadgeteer modules and mainboards and that I’m not that good at electronics. I’m pretty good at electrical circuits.

Hi Yentheo,

You can achieve your goal just by placing an LDR near from the light source, and calibrate it to know more thant just if your lifght is on or off, but also if it is day o night, so that for example, you would be able to deal with the need for tuning on the light when it is already midday !

look a this tutorial with is quite very simple to implement with just an LDR, a resistor, and an Analog Input… :


Why not use a 3-way switch setup, http://www.tinyclr.com/forum/reply/create?id=8341

(I was going to make an ascii diagram, but this link has a good one.)

Another posssibility would be to input in your circuit, a monitoring relay, that use your power supply as primary, and an NO/NC contact that state the presence of power. If you have a friend that is master in electronic, he will probably be able to build something for you based on a TRIAC, but if not, you can opt for a product such as the FINDER 70 SERIES that can serve, even in 3 phasis supplies. And it will also tell you if your light is dead :slight_smile:

See in attachment such a synopsis of what I’m talking about.

The link for FINDER : http://gfinder.findernet.com//assets/Series/96/S70EN.pdf

First thanks for the input.

I maybe didn’t state this but I would like to stay in the high end electronics by using gadgeteer modules or simple electric circuits.

@ LouisCpro If I’m gonna use the Finder 70 Series relay, I can’t read it with a Gadgeteer mainboard, or I would have to make my own module, for which I don’t have the resources or knowledge.

@ Dr9 Correct me if i’m wrong but isn’t the 3-way switch the same as my “hotel-circuit” which I explained above? The problem with that is when I change the switch position I don’t know whether it’s on or off.

If I’m not getting something please explain :stuck_out_tongue: and thanks again for the input. I appreciate it.

You will be able to use the finder with any kind of board as it only need a digital input as shown on my schema

Yes, ‘On and Off’ are relative. the diagram on the 2nd link shows it best. It may be the same as your hotel circuit - different parts call it different things. In the UK it is a ‘2-way’ but in Canada/USA it is called a ‘3-way’ (even though it is 2 switches).

Basically, your relay control circuit will have to be remain in a fixed state (it’s not ‘ON/OFF’ so much as ‘Line 1/Line 2’. The relay should probably be the of the latching variety -otherwise you need to keep it energized to maintain state.

In the US they’re called 3-way because the load itself is one of the “ways”. Two switches plus a load is 3-way. Three switches plus a load is 4-way. Confused me, too, the first time I went looking for the proper switch to implement the circuit.