There's no denying it: two-way switches are pretty neat. Long gone are the days when one had to climb the stairs in darkness, since now the light can be controlled from upstairs too.

But there's something a little unsettling about two-way switches. Unlike their one-way cousins, two-way switches do not have a fixed "on" or "off" position; instead, toggling either switch in the pair toggles the state of the light. When two-way and one-way switches co-exist on a single panel, the switches may be in different orientations, but the lights in the same state! Perhaps one of the worst cases is where a two sets of two-way switches are mounted together, but are set up in such away that all four switches being in the same orientation results in the two lights being in different states!

If even thinking about such a thing makes you cringe, Synchronised Two-way Switches are for you. Although both switches control the light, they behave just the same as one-way switches. This is achieved by mechanically linking the two switches with, for instance, solenoids or (my favourite) hydraulics. In this arrangement, only one of the switches would be electrically connected to the light that is controlled, the other switch controlling it indirectly by throwing the other switch. Now you no longer need to look at the light to know whether it's on or off: a single glance at the switch will tell you all you need to know.
-- Thod, Nov 07 2004

Knife Light Switches http://www.halfbake..._20Light_20Switches
by Rods Tiger. Could be coupled with Thod's idea, for haunted laboratory eerieness. [calum, Nov 07 2004]

Three-Way Switches http://home.howstuf...s.com/three-way.htm
[jurist, Nov 07 2004]

OCD http://omni.ac.uk/b...003469L0003469.html
When the switches aren't tidy..... [ConsulFlaminicus, Nov 08 2004]

I was going to give you a croissant, but I couldn't get it to come out even.
-- ato_de, Nov 07 2004


[Thod]: Not to make a big deal of it, but the items you refer to as "two-way switches" are actually more properly called "three-way switches", or SPDT (single pole double throw) switches. See link.
-- jurist, Nov 07 2004


Yes, jurist is right. And wouldn't be a lot simpler to install a mini-motor, so that when one switch is flipped, a little electric pulse is sent to the opposite switch, activatine the mini-motor and causing the switch to flip?
-- DesertFox, Nov 08 2004


ConsulFlaminicus, OCD can stand for Over the Counter D rugs, too.
-- DesertFox, Nov 08 2004


Perhaps my use of the nomenclature is not quite right, but I tend to think of the whole arrangement as being two-way switches, in that both switches are able to control the lights. The individual switches in the traditional set-up are, as you point out [jurist], SPDT, but in the synchronised system an SPST would be used, effectively with two linked controls.
-- Thod, Nov 08 2004


This idea would quite effectively allow the "up=turned on" and the "down=turned off" visual indication to work with 3 way switches as well.

For the truly round-the-bend folks, they'd have to be servo controlled so that they remain synchronous throughout the range of motion of the switch.

Of course, you could do away with the entire "out of sync" problem by using momentary contact switches that would just tell a relay to toggle the condition of the lights. No fun, that.
-- half, Nov 08 2004


Hydraulics... oh yes. For that whole Victorian feel I'd go for metal push-rods concealed in a wall cavity, though. [+]
-- st3f, Nov 08 2004


Light your way to bed with a candle.
-- wagster, Nov 08 2004



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