Circuit Cellar EQ quiz ca 2002.

[Ian Field]

One of the questions is how do you wire 3 switches to a lightbulb - any one
of the switches can turn the light on or off.

I couldn't figure it out, and couldn't find the answer by google either.

 

[Tom Biasi]

On 6/4/2013 5:00 PM, Ian Field wrote:

One of the questions is how do you wire 3 switches to a lightbulb - any
one of the switches can turn the light on or off.

I couldn't figure it out, and couldn't find the answer by google either.



Look up 4 way light switch.

 

[Ian Field]

"Tom Biasi" <tombiasi@optonline.net> wrote in message
news:51ae5c94$0$19542$607ed4bc@cv.net...

On 6/4/2013 5:00 PM, Ian Field wrote:
One of the questions is how do you wire 3 switches to a lightbulb - any
one of the switches can turn the light on or off.

I couldn't figure it out, and couldn't find the answer by google either.



Look up 4 way light switch.

Got it - thanks.

I googled 3 way light switch and didn't get the animation:

http://users.wfu.edu/matthews/misc/switches/4WayAnimation.html

 

[Michael Black]

On Tue, 4 Jun 2013, Ian Field wrote:

One of the questions is how do you wire 3 switches to a lightbulb - any one
of the switches can turn the light on or off.

I couldn't figure it out, and couldn't find the answer by google either.

I don't know, but surely an extension of having two switches control the

same bulb.

I grew up with one of those arrangements, a switch on the first floor, a
switch on the second floor, and it never worked. The first floor switch
had to be a certain way for the second floor switch to work. And my
mother always said "it must be the switch".

Much later, I took the cover off those switches and looked into it, and it
was nothing more complicated than bad wiring. Once I'd figured it out,
the two switches worked fine.

Michael

 

[Daniel Pitts]

On 6/4/13 2:00 PM, Ian Field wrote:

One of the questions is how do you wire 3 switches to a lightbulb - any
one of the switches can turn the light on or off.

I couldn't figure it out, and couldn't find the answer by google either.

XOR gates.

Or appropriately connected DPDT switches.

 

[ehsjr]

On 6/4/2013 5:00 PM, Ian Field wrote:

One of the questions is how do you wire 3 switches to a lightbulb - any
one of the switches can turn the light on or off.

I couldn't figure it out, and couldn't find the answer by google either.

The question typically refers to 110VAC house wiring.
You use 2 "3-way" (spdt) switches, and one "4-way" (dpdt) switch
as shown below in two diagrams. The second diagram shows the
connection difference when the "4-way" switch is thrown to the
other position. The black (hot) wire is switched and the white
wire is not - white must be electrically continuous to the source.
The wires between the switches are called "travelers".

SPDT DPDT SPDT
o---------o o--------o
/ \-/ \
----o o---[Bulb]---+ Bulb is on
/-\ |
o---------o o--------o |
|
----------------White-----------------------+


SPDT DPDT SPDT
o---------o o--------o
/ \ / \
----o X o---[Bulb]---+ Bulb is off
/ \ |
o---------o o--------o |
|
----------------White-----------------------+

In house wiring, the travelers and the white wire must
be in the same cable or conduit. Typically 14-3 or 12-3 is
run between the junction boxes housing the switches.

Ed

 

[Tim Wescott]

On Tue, 04 Jun 2013 18:06:51 -0400, Michael Black wrote:

On Tue, 4 Jun 2013, Ian Field wrote:

One of the questions is how do you wire 3 switches to a lightbulb - any
one of the switches can turn the light on or off.

I couldn't figure it out, and couldn't find the answer by google
either.

I don't know, but surely an extension of having two switches control the
same bulb.

It is. We have such an arrangement in our hallway, with four switches:
one at the end, and one by each bedroom door.

It was vastly entertaining when the kids were 9 and 14. At least, it was
vastly entertaining for _them_.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

 

[George Herold]

On Jun 5, 1:18 pm, Tim Wescott <t...@seemywebsite.com> wrote:

On Tue, 04 Jun 2013 18:06:51 -0400, Michael Black wrote:
On Tue, 4 Jun 2013, Ian Field wrote:

One of the questions is how do you wire 3 switches to a lightbulb - any
one of the switches can turn the light on or off.

I couldn't figure it out, and couldn't find the answer by google
either.

I don't know, but surely an extension of having two switches control the
same bulb.

It is.  We have such an arrangement in our hallway, with four switches:
one at the end, and one by each bedroom door.

It was vastly entertaining when the kids were 9 and 14.  At least, it was
vastly entertaining for _them_.

Did you have them make a 'state' diagram? Showing for which 'states'
the light was on or off.

.... I know, when I do that as a Dad the kids just roll their eyes.
My 13 yr old daughter has it down pat. :^)

George H.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Softwarehttp://www.wescottdesign.com

 

[Tim Wescott]

On Thu, 06 Jun 2013 06:13:06 -0700, George Herold wrote:

On Jun 5, 1:18 pm, Tim Wescott <t...@seemywebsite.com> wrote:
On Tue, 04 Jun 2013 18:06:51 -0400, Michael Black wrote:
On Tue, 4 Jun 2013, Ian Field wrote:

One of the questions is how do you wire 3 switches to a lightbulb -
any one of the switches can turn the light on or off.

I couldn't figure it out, and couldn't find the answer by google
either.

I don't know, but surely an extension of having two switches control
the same bulb.

It is.  We have such an arrangement in our hallway, with four switches:
one at the end, and one by each bedroom door.

It was vastly entertaining when the kids were 9 and 14.  At least, it
was vastly entertaining for _them_.

Did you have them make a 'state' diagram? Showing for which 'states'
the light was on or off.

I couldn't stop "light wars" long enough to try!

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

 

[Ian Field]

"Daniel Pitts" <newsgroup.nospam@virtualinfinity.net> wrote in message
newseurt.52820$JB5.7611@newsfe26.iad...

On 6/4/13 2:00 PM, Ian Field wrote:
One of the questions is how do you wire 3 switches to a lightbulb - any
one of the switches can turn the light on or off.

I couldn't figure it out, and couldn't find the answer by google either.

XOR gates.

Or appropriately connected DPDT switches.

A single pole changeover at each end and a 2-pole changeover in the middle.

The electrical fittings store probably stocks a switch that changes from
straight through to crossover for this very purpose.

 

[Daniel Pitts]

On 6/7/13 1:51 PM, Ian Field wrote:

"Daniel Pitts" <newsgroup.nospam@virtualinfinity.net> wrote in message
newseurt.52820$JB5.7611@newsfe26.iad...
On 6/4/13 2:00 PM, Ian Field wrote:
One of the questions is how do you wire 3 switches to a lightbulb - any
one of the switches can turn the light on or off.

I couldn't figure it out, and couldn't find the answer by google either.

XOR gates.

Or appropriately connected DPDT switches.

A single pole changeover at each end and a 2-pole changeover in the middle.

The electrical fittings store probably stocks a switch that changes from
straight through to crossover for this very purpose.

Yup, that seems likely. ;-)

I did think of this video which shows a trick way to control three
lights with three switchs with the switches and lights all in "series".

<http://www.youtube.com/watch?v=RkTvDjhImwo>

How it works is here: <http://www.youtube.com/watch?v=mzDTZuFJYX4>

 

[Michael Black]

On Tue, 4 Jun 2013, Daniel Pitts wrote:

On 6/4/13 2:00 PM, Ian Field wrote:
One of the questions is how do you wire 3 switches to a lightbulb - any
one of the switches can turn the light on or off.

I couldn't figure it out, and couldn't find the answer by google either.

XOR gates.

Or appropriately connected DPDT switches.

Considerig logic gates used to be explained with a combination of

switches, I'm sure it's the latter. Indeed, the switches are the
equivalent of the needed gate.

Michael