# Controlling two lights separately with one switch

1. Jun 1, 2009

### hobbes33

I have a single lighting switch at home which controls two sets of light separately, but I have no idea how it works.

Here's what the single switch does when flipped on-and-off quickly,
On -> Light A turns on
Off -> A turns off
On -> Light B turns on
Off -> B turns off
On -> Light A and B turns on
Off -> A & B turn off
...cycles repeat..

Can anyone please tell me what device is making this switch function in such a special way? I have been puzzled over my switch for some time.

Thanks.

2. Jun 1, 2009

### Staff: Mentor

Just sounds like a specialty mechanical latching switch. You could ask about it at the larger home improvement / hardware stores in the lighting section to see if they carry similar switches.

3. Jun 1, 2009

### Staff: Mentor

Turn off the power and remove the switch from the wall and analyze it...

It may even have a name or model number on it.

4. Jun 1, 2009

### DaveC426913

What physical type of switch is it? i.e. is it a simple up/down toggle, like a standard wall switch?

Anyway, the way the switch probably works is using a sort of cam - basically a wheel with three teeth, at 120 degrees (or possibly 6 teeth at 60 degrees). When you switch it on, the cam rotates 60 degrees, and closes a circuit to one light. Then you switch it off, the cam rotates another 60 degrees to an open circuit. Switch again, the cam rotates another 60 degrees, closing the circuit to the second light. Switch again, and it rotates 60 degrees, opening the circuit. Switch a third time and the cam rotates 60 degrees, closing a circuit to both lights. A final switch rotates it to an open circuit.

This is just a guess, off the top of my head. I've never seen a switch like this, but it would work.

5. Jun 1, 2009

### Danger

Does it behave differently if operated slowly? If so, there might be some sort of pulse detector with a logic circuit. Just a thought.

6. Jun 1, 2009

### MATLABdude

Sounds like a standard 3-way switch used in a non-standard configuration.

Common - Hot
Terminal A - Light 1
Terminal B - Light 2

When you flick the switch one way, it redirects the hot leg to one light (current returns via the neutral) and when you flick it the other way, it redirects the hot leg to the other light.

EDIT: Whoops, I just reread your post--it most definitely isn't a three-way switch.

7. Jun 1, 2009

### Averagesupernova

Sounds to me like it is hooked to some kind of stepping relay.

8. Jun 1, 2009

### HempForPres

Definitely magic.

Or DaveC's response....

9. Jun 2, 2009

### KingNothing

If you hear relay clicks, then it uses relays. Otherwise, it could work in lots of different ways! You're an engineer...pull that thing out and look at it!

10. Jun 2, 2009

### TVP45

Sounds like a rotarbivitlum polf pilf.

11. Jun 3, 2009

### CompuChip

Or better perhaps, find out what kind of thing it is and go buy one to look at. I have noticed that things I 'look at' (as in: take them apart) hardly ever work afterwards. If the light switch controls the lights in your room, you may not want to break the 'original' :)

12. Jun 3, 2009

### DaveC426913

I'm going to guess that it is not sold anymore. I'm going to guess that it is also very rare.

13. Jun 3, 2009

### CompuChip

Why? I mean, I never heard of it, but doesn't anyone want that in their house?
Even if just for show / fun? :)

14. Jun 3, 2009

### hobbes33

It's a standard wall switch. It looks no different from other normal light switches in my house, just that this one had the special function. A guest would think that the switch only controls light A since he will have no idea how to operate this special switch and there's no clue to give it away.

I've tried this, but the panel behind the switch is empty. So KingNothing, I wouldn't be able to hear the relays if they exist too.. The device seems to be above the ceiling and I can't spot any peculiar things from the "hatch" in the ceiling.

Anyway, i don't think it's a mechanical rotating switch or something like that, since I failed to mention another property of this switch, my bad. Here it is:
So here's what the switch when it is not flipped quickly.

Fast On -> Light A turns on
Fast Off -> A turns off
Fast On -> Light B turns on
Fast Off -> B turns off
*Pause for more than 1 to 2 seconds
On -> Light A turns on (instead of A & B turning on)
Fast Off -> A turns off
Fast On -> Light B turns on

So it seems that a pause of 2 seconds will cause the device to 'reset' to its original state.

It might be an electronic circuit together with some relays. But that answer would be too boring!! Haha...

15. Jun 3, 2009

### DaveC426913

OK, that rules out a mechanical switch. It owsuld have been your finger providing the energy to toggle the states. Not so if the guts of the thing are in a remote location.

16. Jun 4, 2009

### Born2bwire

Clocked flip-flops replicating a state machine! It's like a home improvement project for bored computer engineers.