1950s GE Low voltage lights

[saintnick]

Hi there, I have an older home with the potential (I think) for some fun home automation/remote control.

Here is the scenario: My exterior lights are controlled by GE low voltage controls. GE provides this product to the Commercial world, but I have not been able to find what I want. They basically are providing spiffed up versions of the old tech today. No real new functionality. The functionality is as follows:
I have 7 light banks controlled by this system, mostly outside. The buttons that control the 7 light banks are low voltage, 18ga wire. they are ST momentary switches. Press to the right and the lights turn on. Press to the left and the lights turn off. Pressing the button activates a relay somewhere else (think by the fixture) that switches the unit from closed circuit to open circuit, (this next part is important) depending only how the button is pushed. So pushing off many times will do nothing. However, leaning on the button will cause the relay to burn out and fail. There is a central "brain" that can control them all. It is a dial for each bank and a rocker switch.

What I want to do:
Eventually remotely control, schedule, and automate the lights based on the seasons. This would allow me to turn the lights off when it is dark, and turn them off when it is light. And have a "oh Shi*" button to turn them all on. There are many software solutions to cover the detection of light and scheduling. What I am looking for is the hardware solution.

I have a thought, to use an internet controlled relay, and then connect that to a series of relays to translate that into a series of on and off through a momentary switch. I can do this, but I need basically 14 IP controlled relays (one for each on and one for each off) and then 5 more for each circuit to turn each on/off to momentary. That is 70 relays.

I think I am making this too hard or just do not know the right approach. Looking for design suggestions mostly, but would entertain a design and build solution.
Thanks for your consideration!
Nick

[Osgeld]

if they are small switches they probably are not handling much current, if thats the case you can use transistors to do the switching which are small, and cheap. since your talking about internet, your talking about a micro controller, which can easily "push" a button for X amount of time then "let it go" without all the extra hoopla

really though, the first thing would be to crack that puppy open and find out what voltages and current its using for the switch control, once you have some stats you can start deciding on a solution from there

[k-ww]

There are at least two possible ways this circuit could be working:

1) the buttons connects one of two diodes to the wires, giving it either positive or negative half-wave power. this method requires two relays at the remote lights - one to self-latch, and one to open up the self-latching circuit.

2) there is a series resistor in the circuit, providing enough power for the remote relay to 'hold', but not pull in, and the switch either shorts this resistor so the relay can pull in, or opens the circuit so that the relay drops out.

You can test for #2 by pushing the button to turn on a bank of lights, and then opening the circuit manually to see if the lights go off. I suspect this is the method used, because you say the relay burns out if you hold the 'on' button down.

You do not need 70 relay to do what you whan, because with a micro, you can turn on any pattern of relays, and do not need to parallel the relay contacts to turn on multiple banks of lights.

[saintnick]

k-ww,
I think your #2 option is the correct one. The relay is a GE RR7 relay (I think latching). Each relay employs a split low-voltage (24V) coil to move the line voltage contact armature to the ON(OFF) latched position. The line voltage at the RR7 is regular old 120v AC. The system has 24v running from a step down transformer to the rocker switches. the 24v then actuates the relay. There are three wires going to each switch. One (the center) is the 24v line, and when the 24v is connected to the left wire, the unit turns off, and when the rocker contacts the right wire with the center, the light turns on.
For the microcontroller, can I hook one of those up directly to the wires? All the wires are conveniently located by the brain. Also, how would I go about putting this together? I am not afraid to use google, just not sure where to start.
Thank you and Osgeld for the advice so far! Glad to hear I have other options than the relays.

[k-ww]

You cannot hook the micro directly to the wires the micro can only supply 3V or 5V at a few milliamperes DC, and the relay is being driven at a high and AC voltage. - your best bet is thru small SPST [single pole, single throw] relays - you would wire one across each set of "on" contacts, and one across each set of "off" contacts, and have the micro drive the relays [most likely thru a transistor or a relay driver chip [look up the "ULN2003A" in digikey, and check the spec sheet.] You would end up needing one pair of relays [on & off] for each light bank.

[saintnick]

I think I see where you are going. Use the micro to turn on the relay and then turn off the relay to mimic the switch.
Any resources that you can point me on how to wire up the ULN2003A?
Thanks again for your help

[k-ww]

Things to do:

1) measure coil resistance of the relays.

2) build/buy a 24V DC supply [full wave bridge rectify the 24VAC that runs the relays now, and 24V regulator circuit], or [buy a 24V DC power supply] that has enough current ouput to drive at least 8 relays [a little extra for Murphy], and also 3.3V or 5V regulated from the 24V for the micro. Tie the negative of both supplies together [if it is not already. - you can find cheap supplies at http://www.mpja.com or http://www.goldmine-elec.com, among other places. [a switching supply will waste less power than a linear supply] Replace the 24VAC [from a transformer] that you are now using with this 24V DC supply.

3) the ULN2003A has 7 inputs, 7 outputs to drive the relays [you will need 2 of the ULN2003A's], a ground connection and a positive connection that you will tie to the +24V positive [this pin is for the 7 clamp diodes that the ULN2003A has. each relay you wish to control connects from the 24V suppy positive to an output of a ULN2003A. If the relays are a long distance from your new controller's location, put a diode directly across each relay's coil, with the cathode of the diode to the side of the coil that connects to the +24V, and the anode to the lead that goes to the ULN2003A's. the inputs of the ULN2003A connect to the micro, to pins that have been programmed as outputs. driving one of the micro's output pins high will cause the relay associated with that pin [via a ULN2003A input/output pair] to be energised. To test this circuit w/o a micro, connect a ULN2003A input pin to the 3V or 5V supply.

[saintnick]

I can do #1.
I think 2 and 3 may be over my head with the exception of the diode on the relay coils. I have done that before. I was planning on the controller and the relays in an enclosure in my router/backup closet. The RR7 relays are distributed about the house.
Would I be able to get away with using this
http://www.redhillnetworks.com/products ... index.html
to use the programmable TTL logic to drive these relays
http://www.sainsmart.com/8-channel-dc-5 ... logic.html
using 1 relay for on and one relay for off? I expect I would need 2 of each for both for the 14 relays needed to do this. Looks like the relays are AC and DC relays - could I hook them up to my 24v line on the switch?

[k-ww]

Yes, wiring those in parallel with the switches would do it. you could use the wbecontrol board's 8th output to select if you are 'talking' to the 7 'on' or the 7 'off' relays. [modify one relay on one board to be normally closed instead of normally open, and use it [the 8th relay] and the 8th relay on the other board to
suppy the 24vac common power to the other 7 relays, so that [8th signal on + other 7 relays] to turn on lights, or [8th relay off + other 7 relays] to turn lights off.

[saintnick]

Thanks! That is great news! I really appreciate the guidance. I'll post a follow up after I get the parts and get one of them wired up. I think the 8th port is a great idea for an all-on, all off solution too.
Thanks again.
Nick