justin13me
Member
- Location
- CANADA
Relay for 3 way switching with 2 wires
- Thread starter justin13me
- Start date
- Status
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
If you want to extend it to a third or additional switches the additional relays will have to implement the cross wired DPDT function of a four-way switch.
Still just the two wires from the SPST switch to actuate it though.
Still just the two wires from the SPST switch to actuate it though.
- Location
- Massachusetts
God this has been difficult for you.
You truly see this thread in entirely different way then I.
The idea was to find a way to do this without adding more wire
Get it?
- Location
- Massachusetts
Condratulations now you got it. :lol:
K8MHZ
Senior Member
- Occupation
- Electrician
It's almost 3 AM. Shouldn't you be in bed??
K8MHZ
Senior Member
- Occupation
- Electrician
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
170327-0915 EDT
K8MHZ:
justin13me has implemented my suggestion 1 in post #36 to divorce the "exclusive or" from the input switches and locate the "xor" somewhere else.
The truth table for XOR is:
A B . Out .... A and B are binary inputs and Out is the resulting binary output
0 0 = 0
0 1 = 1
1 0 = 1
1 1 = 0
It should be noted that this a basic part of binary addition. Binary addition is:
C A B . Out where C is carry from the previous stage
0 0 1 = 1
0 1 0 = 1
0 1 1 = 0 with carry
1 0 0 = 1
1 0 1 = 0 with carry
1 1 0 = 0 with carry
1 1 1 = 1 with carry
For comparison AND is:
A B . Out
0 0 = 0
0 1 = 0
1 0 = 0
1 1 = 1
Have not proofread, have to leave.
.
K8MHZ:
justin13me has implemented my suggestion 1 in post #36 to divorce the "exclusive or" from the input switches and locate the "xor" somewhere else.
The truth table for XOR is:
A B . Out .... A and B are binary inputs and Out is the resulting binary output
0 0 = 0
0 1 = 1
1 0 = 1
1 1 = 0
It should be noted that this a basic part of binary addition. Binary addition is:
C A B . Out where C is carry from the previous stage
0 0 1 = 1
0 1 0 = 1
0 1 1 = 0 with carry
1 0 0 = 1
1 0 1 = 0 with carry
1 1 0 = 0 with carry
1 1 1 = 1 with carry
For comparison AND is:
A B . Out
0 0 = 0
0 1 = 0
1 0 = 0
1 1 = 1
Have not proofread, have to leave.
.
peter d
Senior Member
- Location
- New England
You guys.....:slaphead::happyno:
- Location
- Massachusetts
ptonsparky
Tom
- Occupation
- EC - retired
Solution was simple with the added relay. The explanation in binary format takes a bit longer.
- Location
- Massachusetts
:thumbsup:
Switching circuit
Switching circuit
Here is the way I would have did 7 years ago
After I drew the diagram I notice I should have used a threeway switch and used one traveler and the common
so the switch would not have the off and on the handle.
Switching circuit
Here is the way I would have did 7 years ago
After I drew the diagram I notice I should have used a threeway switch and used one traveler and the common
so the switch would not have the off and on the handle.
Last edited:
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
I am glad that the OP specifically said that the plan is to simply run new wire but continue the discussion for theory fun; because I am happy to dive in
My first thought along the lines of over-complicating things so that 2 wires could be used in a 3-way setup is 'diodes'. Use a 4 way switch with a diode connected across two terminals. Depending on switch position the circuit will conduct electricity in one direction or the other.
With 2 diode/switch assemblies you conduct current only when both diodes are 'pointed the same way'. This gets you 3-way switching with only two conductors between the switches. Problem is that you now have reduced voltage at your load, so you still need something to provide full voltage to the load.
I think that ronaldrc has the most elegant solution other than just running the new conductors. As I understand it, he used a single pole switch to turn a relay on and off, and wired the terminals of the relay to look like a 4-way switch. So you would add in a new 3-way/4-way switching circuit to control the light, with _one_ of these 'switches' actually being a relay, and you would use the existing 2 conductors to control the relay.
-Jon
My first thought along the lines of over-complicating things so that 2 wires could be used in a 3-way setup is 'diodes'. Use a 4 way switch with a diode connected across two terminals. Depending on switch position the circuit will conduct electricity in one direction or the other.
With 2 diode/switch assemblies you conduct current only when both diodes are 'pointed the same way'. This gets you 3-way switching with only two conductors between the switches. Problem is that you now have reduced voltage at your load, so you still need something to provide full voltage to the load.
I think that ronaldrc has the most elegant solution other than just running the new conductors. As I understand it, he used a single pole switch to turn a relay on and off, and wired the terminals of the relay to look like a 4-way switch. So you would add in a new 3-way/4-way switching circuit to control the light, with _one_ of these 'switches' actually being a relay, and you would use the existing 2 conductors to control the relay.
-Jon
ptonsparky
Tom
- Occupation
- EC - retired
Ron's brings back memories of a 1950s era project we updated to PLC and HMI. That was fun to figure out how things ran. They had similar logic to his.
JFletcher
Senior Member
- Location
- Williamsburg, VA
Very cool... there's just one small remaining problem:
If those switches were mounted vertically, they'd violate 404.7.
K8MHZ
Senior Member
- Occupation
- Electrician
How does any decora switch comply with 404.7?
Plus, since the OP is in Canada, I don't think it applies, anyway.
I am glad that the OP specifically said that the plan is to simply run new wire but continue the discussion for theory fun; because I am happy to dive in
My first thought along the lines of over-complicating things so that 2 wires could be used in a 3-way setup is 'diodes'. Use a 4 way switch with a diode connected across two terminals. Depending on switch position the circuit will conduct electricity in one direction or the other.
With 2 diode/switch assemblies you conduct current only when both diodes are 'pointed the same way'. This gets you 3-way switching with only two conductors between the switches. Problem is that you now have reduced voltage at your load, so you still need something to provide full voltage to the load.
I think that ronaldrc has the most elegant solution other than just running the new conductors. As I understand it, he used a single pole switch to turn a relay on and off, and wired the terminals of the relay to look like a 4-way switch. So you would add in a new 3-way/4-way switching circuit to control the light, with _one_ of these 'switches' actually being a relay, and you would use the existing 2 conductors to control the relay.
-Jon
Thanks:
I started to posted something with Diodes and then this happen come to mind. Its just a little simpler
Anyway I got bored and made a GIF of this circuit.
justin13me
Member
- Location
- CANADA
Thanks everyone for the great feedback and input! It turns out I don't have (2) spare 24vac relays so I went to the supplier to get it and they only had the 'ice cube' style w armature. It's a 2 pole: has 2 NO, 2 COM, 2 NC but only 1 A1 and A2. The guy at the counter says 'it's like having 2' and I believe him.. (They're only $16 a piece, stupid me shoulda taken 2). I take to site, happy at saving from the labour intensive work of running new wires across the warehouse but in no time am stumped.. Is it possible still when only 1 input to turn on/off this relay? I think it's not as previously I had to turn each (relay) on and off with the load. However contactors are so versatile maybe it is possible but just above my pay grade lol
justin13me
Member
- Location
- CANADA
Visual aid..
justin13me
Member
- Location
- CANADA
I don't think it works w the double poles on single relay as every time a switch is pressed the contacts have to change states. Should have been obvious, but maybe (?) still possible...? As its 24V the neutral could be switched but I don't think it would make a difference. I'm going to stop pursuing, I have a second relay for tmrw
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