Light switch in my room is operated using a relay (rated 24v-8v). It just like in
the picture http://home.howstuffworks.com/relay1.htm
The top "battery" is ofcourse regular power. The bottom "battery" is operated by
I'd like to add another switch to the relay. How do I do add it to this system?
I have another 24V transformer with a switch. If we have the
http://home.howstuffworks.com/relay1.htm system as an example - could I add
another switch+battery to the same coil? Actually the relay is a latching relay.
Does not look like that at all. But that is not the point here.
Electrically speaking a similar situation would be if I have two transformers and
connection the their hot wires and also their "cold" wires. The relay is allready
connected to a transformer. Can I connect another transform there also? What
would happen? It's not a short at least.
I've included a small picture to illustrate what I mean.
Your picture shows the two switches in series with each other. That won't
work. You have to install the second switch in parallel with the first one,
this way either switch will ratchet the relay one notch each time it's
RBM's correct: what you want, apparently, is a "wire OR" circuit (so
called because either one switch or the other will operate the device).
The way you have it wired is a "wired AND" circuit.
HOWEVER: if you're using transformers as power sources, there's an
additional problem. If you use more than one transformer connected
together, they have to be in phase, or they'll cancel each other out.
You could get around this by rectifying the current to DC, but then you
might have to use a DC relay instead of the AC one you have now.
Washing one\'s hands of the conflict between the powerful and the
powerless means to side with the powerful, not to be neutral.
With a regular relay you could use two regular 120V 3-way light switches,
but connected to the 24 volt.
With a double pole relay, you could use one pole to latch on the relay and
use two normally open momentary push button switches wired in parallel to
turn the relay/light on, then two additional momentary normally closed
switches wired in series to the latching circuit to turn the light off.
Or use a certain type of toggle/switching relay and use two normally open
momentary push button switches wired in parallel to turn the light on/off.
"John Smith" wrote in message
Depends on what you are trying to accomplish.
You could just add a 2nd switch in parallel with the 1st switch. But
then the 1st switch must always remain off for the 2nd to work.
You could add a second switch in series with the first, but now the 1st
would always need to be on in order for the 2nd switch to work.
If you want both switches to function independently then you would need
to change both switches to 3 way type.
Hook the battery to the common terminal of the 1st switch.
Run 2 wires (travelers) over to the 2nd switch.
Run another wire from the common terminal of the 2nd switch back back to
the relay coil.
Don't add any more voltage sources to the coil or you will likely burn
Get a book on basic electricity concepts. Then draw out your circuits on
Thank good ness the OP is only dealing with the low voltage side of
this circuit. If it was was regular line voltage they's be deadly (or
Sounds like it is momentary contact switch which 'trggers' some sort
of remote light control analog or semi solid state relay. A 'sort of'
push button operation.
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