I recently acquired a new home... and I'm already planning projects for it even though we haven't closed yet. The home is equipped with a GE Low Voltage Lighting system from 1970 or so. Basically it uses 24 vac pulsed from the switches to the relays/solenoids in a box in the basement. In the kitchen and master bedroom there are two 12 position control switches to turn on/off the other lights in the house. I'd like to replace each of these with something I can control via my phone or touch panel.
I want to keep the switches so ordinary people can control them (aka the wife)... But I'd like to be able to use an Arduino or other type of controller to get things done. I assume I'd need to switch on/off a relay on each red/black wire for the switch? Not exactly sure... suggestions welcome! Also some way to sense if the light is on or off would be useful. Here is a diagram with an idea of how it works. What this doesn't show is the 12 position switches in the Kitchen and M.Bedroom and my exact setup... Any ideas for me?
My parents built a house in the mid 1960s that had a similar low voltage lighting system. The main control panel was in the master bedroom and had things like all external garden lighting on or off, and I assume they could control inside lights also but never saw them use it for that.
From a technical point of view it's not a complex system to control from an arduino, but building it, installing it, and interfacing will be a mechanical and electrical challenge. The arduino part would have to stay in the basement near the main control box. Each light circuit you wish to control with the arduino would require two SPST relays (one to turn the light on and one to turn it off) as you need to generate short pulses not steady states to control the existing latching relays in the main control box. You would wire your two new relays to each of the three wires that the manual switches wire to in that wiring drawing.
I figured it wouldn't be too difficult... I was wondering, instead of locating the arduino in the basement if I could replace one of the 12 position panels with it? That essentially has the same connections I would be adding in the basement. I'd obviously need to provide more details once I move in of course, but do you have any suggestions on monitoring whether or not a light is on? I guess you'd have to do something with the line voltage to see if the solenoid is providing the load power or not, I dunno.
bbowers:
I figured it wouldn't be too difficult... I was wondering, instead of locating the arduino in the basement if I could replace one of the 12 position panels with it? That essentially has the same connections I would be adding in the basement. I'd obviously need to provide more details once I move in of course, but do you have any suggestions on monitoring whether or not a light is on? I guess you'd have to do something with the line voltage to see if the solenoid is providing the load power or not, I dunno.
Yes it should be possible to interface the arduino and it's new relays near or in the remote control panel. However without a diagram of the remote control panel you may have difficulty figuring out what is what with the existing wiring and how to wire your new relays into the system. Having actual feedback signals to the arduino that specific lighting loads are actually being powered or not, or harder yet, if they are actually drawing any current (missing or burned out lamp) is a pretty complex and expensive proposition, not impossible but more complex and more expensive. That information would be only available at the main control panel in the basement and of course would mean you are also having to interface into the 120vac side of the lighting circuits, not just the 24 volt control system side. Note that your existing system does not tell one if a specific circuit is presently on or off, but rather just gives you the ability to specifically turn a circuit on or off.
Right, very good. I guess the interface would give an on/off button or two and if I wanted to turn all the lights off regardless of status I'd just hit off. As for the actual physical switches, if I hit on multiple times, the light only turns on once and stays on obviously. The only actual indicator that the light is on, is that the light is on haha. I'll worry about that side of it later I guess. Just interfacing with it would be awesome. Oops I may have forgot to turn a light off... log in and hit an all off button or something... or maybe I'd like to remotely turn on the garage light, maybe we were out later than expected and didn't do it before we left. That's obviously possible too which is nice.
How much current do the 24VAC solenoids need? You can almost certainly use opto triacs to switch them, which would be quieter, cheaper and smaller than relays. For example, http://www.farnell.com/datasheets/1244301.pdf will switch 0.9A.
dc42:
How much current do the 24VAC solenoids need? You can almost certainly use opto triacs to switch them, which would be quieter, cheaper and smaller than relays. For example, http://www.farnell.com/datasheets/1244301.pdf will switch 0.9A.
I believe most if not all of the relays in my place are these ones...
dc42:
How much current do the 24VAC solenoids need? You can almost certainly use opto triacs to switch them, which would be quieter, cheaper and smaller than relays. For example, http://www.farnell.com/datasheets/1244301.pdf will switch 0.9A.
They appear to actually be 24 volt DC latching relays as the drawing of the control box shows a diode being used to half wave rectify the 24vac to drive the latching relays.
dc42:
How much current do the 24VAC solenoids need? You can almost certainly use opto triacs to switch them, which would be quieter, cheaper and smaller than relays. For example, http://www.farnell.com/datasheets/1244301.pdf will switch 0.9A.
They appear to actually be 24 volt DC latching relays as the drawing of the control box shows a diode being used to half wave rectify the 24vac to drive the latching relays.
Lefty
The data that the OP refers to says 24VAC at 325mA, or 30-38V half or full wave or pure DC. As long as it's not smoothed DC, the opto triac I suggested should work fine. It costs only GBP 0.32 from Farnell.
