Hello
Looking for 2 channel relay board with dpdt relay AND opto-isolation
I can find relay boards that are opto-isolated but relays are spdt only
I can also find relay board with dpdt relays, but they are not opto isolated...!
Any links for boards that have both?
Thanks
That is a fairly specific part. If you are desperate you can get the opto isolator as a separate item from Sparkfun SparkFun Opto-isolator Breakout - BOB-09118 - SparkFun Electronics. That would drive the relay board you linked to. As far as two on one I do not know of any,
Hi,
Is there a reason you need opto-isolation?
The relay provides the isolation from the input to the output load current.
The non opto PCB will have all the back EMF protection diodes that the opto isolated PCB will.
Thanks... Tom.. 
Ever the "XY Problem"!
Why do you want a DPDT relay?
Please do not say it is for reversing a motor! To reverse a motor, you use a common 2 channel relay board with SPDT relays, not a DPDT relay which for the same size, generally has less durable contacts.
Even so, there are far better solutions than relays for reversing a motor...
Assuming a valid reason for wanting dpdt, why not gang 2 channels of 4-channel spdt relay module?
wvmarle:
Even so, there are far better solutions than relays for reversing a motor...
It's not to reverse a motor....!
Paul__B:
Ever the "XY Problem"!Why do you want a DPDT relay?
Please do not say it is for reversing a motor! To reverse a motor, you use a common 2 channel relay board with SPDT relays, not a DPDT relay which for the same size, generally has less durable contacts.
I do model train in DCC
I need to switch the signal which is 2 wires
I could do 4 SPDT (I thought about it) but if 1 relay fails, I may mix signals and not sure it's good for the DCC central or decoders in the locomotives....
I guess the next point is why opto isolated , given the relay isolates it contacts from the coil ?
I'm sure there are far smarter ways of switching a signal than by using relays, which are almost certainly the wrong tool for the job.
Now if you explain more precisely what you actually want to do, maybe we can give you better suggestions.
Wouldn't any 4-channel SPDT relay board be capable of that?
There are plenty of those around.
CrossRoads:
Wouldn't any 4-channel SPDT relay board be capable of that?
There are plenty of those around.
Probably.......can 1 ouput drive 2 relays (using one of those easy to find 4 relay boards)?
Yes.
PaulRB:
Yes.
Just wire 1 jumper from the output to both input, that's it?
french_guy:
Just wire 1 jumper from the output to both input, that's it?
Yes, basically. Just check the spec on your relay board to ensure that the current required for the two optoisolators doesn't exceed the pin limit on your Arduino (40mA).
Yes.
But what is being switched? Power for something, or just a data signal?
If data, analog or digital?
it's digital signal.....
What voltage?
wildbill:
Yes, basically. Just check the spec on your relay board to ensure that the current required for the two optoisolators doesn't exceed the pin limit on your Arduino (40mA).
Make that 20 mA (40 mA is the absolute max and not to be used as design spec).
french_guy:
it's digital signal.....
The 74HC125 or 74HC126 can easily switch digital signals.
