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SPDT relay question

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xeeshan74

New Member
Hello Experts

I am trying to control my light switch from RF driven relay board ( that I ordered online ) but later I realized that this Light switch is a 3 way Switch(Can be turned on off from 2 locations in the room).

One idea is to just seal the second switch and install RF switch in the first Switch. But what If I want to keep the Second switch as a manual Light switch while install the RF Switch in the first panel.


Any ideas around this ??
How to acheive such a thing

Practical Scenario

Lets say I push a button on my remote to turn on the light.

Then someone used the second wall mounted switch to turn off the Light.

I think the impact of such thing will be that my RF relay driven board will keep the relay energized whithout knowing if the buld is on - or off .


Any insights greatly appreciated.
 

Brevor

Member
If your relay board has both N.O. (normally open) and N.C. (normally closed) contacts it should be no problem. Just wire them up the same way the switch you are replacing is wired.
 

xeeshan74

New Member
Yes I can see the N.O and N.C there.
But dont you think if relay is energized and light on ON , and if I toggle the manual switch (on the other wall) does it going to automatically de-energize the relay and turn it off or the current will keep flowing ??
 

crutschow

Well-Known Member
Most Helpful Member
As you stated initially, if you wire the relay as a three way switch, then it will not know whether the light is on or off as controlled by the manual switch. The relay will act just the same as a manual switch would i.e toggling the relay will switch the light to the opposite state.
 

xeeshan74

New Member
Thx crut for the reply.
Is there a way to automatically cut the power to the relay if it is in opposite state without interfereing with the state of the light i-e in OFF state due to manual switch toggle.
 

ronsimpson

Well-Known Member
Most Helpful Member
I think you have a 3 way switch and want to go to a 4 way switch. Both wall switches work the way they did and the relay board also switches.

How 4-way switches work -- an animation
This link shows how a 4 way switch works. Watch the animation!!!
A 3 way switch is the same but the middle switch is missing.
If your relay board had a DPDT relay then it could be the middle switch.
so....
Use the relay board as the right switch. Replace one of the wall switches with a "4 way" type switch to be the middle switch.
Confused?
 

xeeshan74

New Member
Nah .. not confused.. makes sense
But I think the fundamental question of not keeping the relay energized is the one I am looking for.
 

ronsimpson

Well-Known Member
Most Helpful Member
In a 4 way or 3 way switch the relay has a 50% chance of being energized.
another idea:
Get a latching relay. It only takes power to change the state of the relay but no power to stay in a state. Use the RF realy to drive the latching relay. I have not though on how to do that. Some latching relays have two coils. ON and OFF. Some have only one coil.
 

xeeshan74

New Member
Ohh yeah I think thats it Latching relay is the answer. I will try to Modify the circuit to accomodate that. Any one here willing to help if I post the symantics??
 
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