I had an idea about this in high school; wish I had patented it then. Something on another forum triggered the memory. Don't know if it is available commercially.

The topic is 3-way house light switches, and how the toggle position does not always reflect the On-ness of the lights,

Replace the toggle switch with a SPST pushbutton switch, and a toggle flipflop driving a TRIAC. That can be a stand-alone switch, or there can be as many remote switches as you want, all in parallel. Any one of them can toggle the flipflop from whatever state it is in to the other one. Cosmetically, the master switch with the electronics and TRIAC would look exactly the same as the remotes - a simple pushbutton dome in a standard wall box device.

The basic approach would lose its toggle status with every power blink. BUT, in an era of a SOT-26 uC for 44 cents in *ones*, the solution is one of them critters that stores the toggle state in flash.

ak

 

how the toggle position does not always reflect the On-ness of the lights,

Don’t see how your solution solves the problem. There is still no indication of the light status.

 

The problem for the person on the other forum is that with standard 3-way toggle switches, sometimes up is off and sometimes down is off, so feeling for the right switch in the dark is, for unknown reasons, a minor issue. With a simple pushbutton, there is no indication so no ambiguity, which I think is an improvement.

In my house there are some upstairs hallway lights that have three switches: foot of the stairs, top of the stairs, and end of the hall. I have them oriented such that one of the OFF conditions is all switches down, but there are other OFF combinations with some switches up. AFAIK there is no commercial switch for a 4-switch arrangement. The proposed control system removes that limitation, for some unknown bizarro situation.

ak

 

Okay, I misunderstood the original problem. I thought you were saying that you could not tell by looking at the switch whether the light was on or not.

 

AFAIK there is no commercial switch for a 4-switch arrangement. The proposed control system removes that limitation, for some unknown bizarro situation.

Of course there is, we used to call them 'Intermediate' switches you can have any amount you wish.

 

The problem for the person on the other forum is that with standard 3-way toggle switches, sometimes up is off and sometimes down is off, so feeling for the right switch in the dark is, for unknown reasons, a minor issue. With a simple pushbutton, there is no indication so no ambiguity, which I think is an improvement.

I don't see how the problem is solved by your suggestion. How is feeling for a pushbutton switch that gives no indication of the light's status any better than feeling for a toggle switch that gives no indication of the light's status. What is the minor issue associated with this ambiguity of the switch position. If the switch controls the light where you are at, the fact that you are in the dark is a strong indicator of the light's status. If it controls a light that is out of sight, then neither gives any indication.

[/QUOTE]
In my house there are some upstairs hallway lights that have three switches: foot of the stairs, top of the stairs, and end of the hall. I have them oriented such that one of the OFF conditions is all switches down, but there are other OFF combinations with some switches up.
[/QUOTE]

The preferred arrangement is that whatever is being controlled should be OFF whenever ALL of the switches are in the down position. There's not standard that requires this. Plus, while all electricians clearly know that any switch can turn the light on or off regardless of the states of the other switches (assuming none are in the "halfway" position), the vast majority don't grasp that the circuit can be wired so that the light is always in the same specific state for the same state of all the switches and will argue that it is not possible, that it doesn't even make sense, to claim to be able to wire things so that the light is always off if all of the switches are down. With one exception, every electrician I have ever had do any work involving a three- or four-way circuit I have asked them to wire them so that the light is off when all the switches are down and every one of them, except that one rare exception, confidently insisted that that couldn't be done because any switch could turn the light on or off. So I've had to just let them do the work however they wanted and then insist that they turn one of the switches over (or swap the wires on it) if they did it wrong. Some of them then acknowledged that what I said was true, but many just shook there heads. One guy was so adamant that after wiring a 4-way circuit involving four switches, I bet it $100 against his $10 that he could not find a way to move the switches so that they all be down by the light still on. He tried for nearly an hour (since there are only sixteen possible combinations of switch states, he must have worked his way through all of them many times) and, in the end, walked away still unconvinced. But I walked away with his $10.

AFAIK there is no commercial switch for a 4-switch arrangement. The proposed control system removes that limitation, for some unknown bizarro situation.

Sure there is. It's known as a 4-way switch. You can construct one using a DPDT switch. A commercial 4-way switch is wired internally so that two wires come into it and two wires leave it and what the switch does is swap which input wire is connected to which output wire. The reason it's called a 4-way switch is because it has four wires connected to it. The same way that a 3-way switch has three wires connected to it. These don't include the safety ground connection that is usually connected to the metal switch frame.

 

I had an idea about this in high school; wish I had patented it then. Something on another forum triggered the memory. Don't know if it is available commercially.

The topic is 3-way house light switches, and how the toggle position does not always reflect the On-ness of the lights,

Replace the toggle switch with a SPST pushbutton switch, and a toggle flipflop driving a TRIAC. That can be a stand-alone switch, or there can be as many remote switches as you want, all in parallel. Any one of them can toggle the flipflop from whatever state it is in to the other one. Cosmetically, the master switch with the electronics and TRIAC would look exactly the same as the remotes - a simple pushbutton dome in a standard wall box device.

The basic approach would lose its toggle status with every power blink. BUT, in an era of a SOT-26 uC for 44 cents in *ones*, the solution is one of them critters that stores the toggle state in flash.

ak

Your solution (the question of utility aside) has a number of problems with it. First, you are throwing electronics at a problem that uses a simple mechanical switch. Not only is there the cost and complexity issue, but also a reliability issue. The switches in most homes never fail even after a century or more of service (although, given the general decline in quality, that may not be true going forward). Even the ultra cheap $2 3-way switches you get at Home Depot will likely outlast you.

What is the likelihood that every one of your switch arrangements in a typical house, with triacs and microcontrollers, is going to go even ten years without at least one failure?

And let's consider cost. You mention 44 cents for a microcontroller. Let's call it $0.25 in large quantity, The largest homebuilders (just in the U.S.) build over 50,000 homes a year. A typical home probably has five or more 3-way circuits in it between stairways and hall ways. So just for the microcontrollers you have $60,000 in lost profit right off the bottom line. Not to mention the greater cost of the additional components. You've also increased the complexity of the installation. How are all of these SPST switches communicating with the master? How often is the installation going to get messed up?

If someone WANTS to just have a pushbutton at each switch location to control the same light from multiple places, there are a number of home automation solutions out there, and have been for decades.

Or, they can just swap out the existing 3-way switches with an illuminated 3-way switch in which the toggle handle glows whenever the light is off.

 

Or, they can just swap out the existing 3-way switches with an illuminated 3-way switch in which the toggle handle glows whenever the light is off.

We have a solution. No more “fumbling around in the dark.”

 

We have a solution. No more “fumbling around in the dark.”

My last house had one of these on the stairway going down from the open loft area of the upper floor to the main floor -- and it was a lifesaver. Because of the arrangement of the stairs and the walls, you had to step down a couple of steps to easily reach the switch -- or really lean over to reach it from the loft floor. So when you came out from the bedroom in the middle of the night, you had to cross the loft from the side of the stairs opposite the switch. Just having that slight illumination was all that was needed to make it easy to get there safely. Without it, I can almost guarantee that one of us (probably me) would have taken a tumble down the stairs at least once. Since this isn't the kind of thing that the home builder would likely have thought about, I'm guessing the prior owner (who had the house built) might have learned that lesson the hard way. Personally, I would have put a 4-way switch to control the light in the loft with a switch next to the two small bedrooms (which is where the actual switch was), one next to the master bedroom, and one next to the stairway switch.

 

Because of the arrangement of the stairs and the walls, you had to step down a couple of steps to easily reach the switch -- or really lean over to reach it from the loft floor

Wow, does that ever sound like a code violation.

 

Don't know why I'm not able to insert quotes, so I did a copy and paste.
@AnalogKid said: "The problem for the person on the other forum is that with standard 3-way toggle switches, sometimes up is off and sometimes down is off, so feeling for the right switch in the dark is, for unknown reasons, a minor issue. With a simple pushbutton, there is no indication so no ambiguity, which I think is an improvement."

I'm struck by the statement "Feeling for the right switch in the dark is, for unknown reasons, a minor issue." If it's dark then the light is either off or burned out.

Feeling for the RIGHT switch in the dark? If it's dark and there are multiple switches, in my household I know which switch turns on what light. Even in the dark I know which switch does what. In my kitchen there's a switch for the light over the sink and right next to that switch is another switch for the garbage disposal. The switch closest to the sink is for the light. That is to say it's the switch on the left (since the switch is on the right hand side of the sink).

I don't know what the system is and I think MaxHeadRoom knows what I'm thinking - since it appears he may be thinking the same thing; I've known of a system where a light is controlled by a relay. Each time the relay is activated it flips a switch. Based on a cam it either switches it on or it switches it off. With each activation of the relay the light state changes. It's controlled by a single push button. But what I think Max is talking about is a system with two push buttons and a latching relay. One button activates it and the other deactivates it. At no time other than the push of the button is the relay powered. Hence, no wasted power, no excess heat. And you can have as many remote buttons as you like all connected to the same relay and light. Stayed in a hotel room that had push buttons. My experience with that system was that the system had many failures.

As for 3 way switches - you're always going to have either both up or down and the light is on (or off) OR one switch is up and the other is down. Just works out that way. As for ascertaining the status of the light - I'm assuming this is a light that is remote and can not be observed from where the switches are. The only thing I can think of is having an indicator light indicating when there's current flowing through the switch. If the indicator light is on then the remote light is on.

I have a shop over the garage. Sometimes I forget to turn the lights off when I leave the shop. At night I discover the lights on and I have to go outside to the shop to turn the lights off. Running a 4-way switch system to be able to turn the lights off remotely is impractical. There's already a 3-way setup where I can turn the lights on from the garage OR from the shop door on the deck.

Anyway, that's all I got. An indicator lamp.

 

OK, let me be more clear.

The motivation for original question that I saw is not clear. The question was about a switch that has an electro-mechanical activator in it such that when one switch is moved manually to the up (ON) position, all of the other switches move to the same position so they all agree with the light status. His question, not mine. I don't know the exact perceived problem, and don't really care. It triggered a memory of an idea I had when I was 15, about an alternate way to have multiple switches control one light. The microprocessor had not yet been invented, CMOS was brand new, I knew a little about toggle flipflops, there were TRIAC articles in Popular Electronics and Radio Electronics about light dimmers and color organs, etcetcetc. I knew back then that losing light status after a power outage was a problem, but had no idea what to do about it. It was an idea, not a manufacturing document.

I've already thought about the cost and reliability issues. I didn't think I needed to go into this level of detail.

1. There are light dimmers in my house that are decades old. Given that pots are less reliable than switches, pots with alternate-action push-push switches on them are less reliable than just about anything, and I actually do know how to design protection into an off-line circuit, I'm not concerned about reliability.

2. This is not about cost. I'm well aware that a switch that has been under constant development for over 100 years is pretty well tweaked up for both cost and reliability. OTOH, I've seen electronic switches in lighting stores, the ones with timed dimming, multi-step dimming, programmable timers, etc. for way over $20. The market is there if the trick is tricky enough.

3. One mistake in my original post - I would make the shape and location of the button identical to that of the rectangular opening in a standard wall plate, so you could use a standard wall plate.

ak

 

These days, there are wireless switches that can replace 3-way switches. I have a set in my kitchen where I had some renovations done several years ago. When the dust settled from the renovations, we realized it would be very convenient to have a switch at the bottom of the stairs leading to the kitchen. We hadn't thought about it during the construction planning so no switch was installed there. I found a wireless switch that replaced the original wall switch. The particular switch I used allows for a remote that can be placed, in my case, at the bottom of the stairs. It is a Lutron Caseta brand part and the remote is slim enough to look like a regular wall switch complete with a standard cover plate.

 

If someone WANTS to just have a pushbutton at each switch location to control the same light from multiple places, there are a number of home automation solutions out there, and have been for decades.

These days, there are wireless switches that can replace 3-way switches.

You just made one of my points. Those solutions do not cost $2 at Home Depot, and yet they are still selling well enough to stay on the market after "decades."

ak

 

And let's consider cost. You mention 44 cents for a microcontroller. Let's call it $0.25 in large quantity, The largest homebuilders (just in the U.S.) build over 50,000 homes a year. A typical home probably has five or more 3-way circuits in it between stairways and hall ways. So just for the microcontrollers you have $60,000 in lost profit right off the bottom line. Not to mention the greater cost of the additional components. You've also increased the complexity of the installation. How are all of these SPST switches communicating with the master? How often is the installation going to get messed up?

There is a lot to unpack here. More later.

ak

 

Post #11 - I don't know what the system is and I think MaxHeadRoom knows what I'm thinking - since it appears he may be thinking the same thing; I've known of a system where a light is controlled by a relay. Each time the relay is activated it flips a switch.

No, I am referring to the standard method using what during my training in the UK we called , intermediate switches, once you need more than the simple two 3way switch pair.

 

You just made one of my points. Those solutions do not cost $2 at Home Depot, and yet they are still selling well enough to stay on the market after "decades."

ak

Yep. In my case it was worth the $60 to use the wireless switch rather than to tear up newly finished drywall to pull wire.

 

Perhaps understanding the need is key to finding a solution. Obviously there are numerous commercial solutions already on market. I'm stuck trying to understand how searching for a light switch in the dark and finding its position (up or down) tells you whether the light is on or off. If it's dark - the answer seems rather obvious to me.

 

The preferred arrangement is that whatever is being controlled should be OFF whenever ALL of the switches are in the down position.

That might be true in the States, but not necessarily so in other countries. Here in the UK, Up is normally Off.

 

That might be true in the States, but not necessarily so in other countries. Here in the UK, Up is normally Off.

Also Canada, It took me a long time to get used to it!