a relay board to recommend

[rossw]

Don't be insulting.
Wikipedia says "Many SSRs use optical coupling."

 
"optical coupling" is not the same as "an optoisolator".
As for insulting: please don't insult us by posting crap that is utterly irrelevant, and anyone with an ounce of knowledge or 3 seconds of research would have already have seen wasn't even worth posting!
 
You virtually "demand" CAI redesign their product because it doesn't do what YOU want to mis-use it for.
You deride and defame "all Chinese relay boards" because they don't work the way YOU want to mis-use them.
You don't even understand when you attempt to put me down, that your own choice of terms are contradictory or at least irrelevant simply because you don't "get" the implications of the word or concept...
 
Seriously... get a clue, or stop posting like you're gods gift...

 

[Efried]

"optical coupling" is not the same as "an optoisolator".
As for insulting: please don't insult us by posting crap that is utterly irrelevant, and anyone with an ounce of knowledge or 3 seconds of research would have already have seen wasn't even worth posting!
 
You virtually "demand" CAI redesign their product because it doesn't do what YOU want to mis-use it for.
You deride and defame "all Chinese relay boards" because they don't work the way YOU want to mis-use them.
You don't even understand when you attempt to put me down, that your own choice of terms are contradictory or at least irrelevant simply because you don't "get" the implications of the word or concept...
 
Seriously... get a clue, or stop posting like you're gods gift...

Ok may be you are upset because I have proven now that for the old BRE version the password was transmitted in plain text. I'm not angry at CAI because they are so helpful, but there a few things one cannot accept. This topic is closed for me.
And yes I stand to the fact that I'm trying to do complicated things with the WC. And I have no education in electronics, that is as far I have understood the clientele for WC, because others are doing microcontroller projects. 
I will ask the moderator of this forum that you are no more allowed answering my postings, because you are overacting- very helpful but fragile and insulting.
Optical coupling is explained as such in Wikipedia :"The control signal must be coupled to the controlled circuit in a way which isolates the two circuits electrically."

 

[rossw]

Ok may be you are upset because I have proven now that for the old BRE version the password was transmitted in plain text.

 
Your original posting about plaintext passwords made no reference to BRE as I recall.
 
 

And yes I stand to the fact that I'm trying to do complicated things with the WC.

 
None of the things I've seen you doing so far have been particularly complicated.
 
 

And I have no education in electronics

 
Perhaps you would do well to ask in a more suitable manner, and listen to the replies of those who do then?
 
 

Optical coupling is explained as such in Wikipedia :"The control signal must be coupled to the controlled circuit in a way which isolates the two circuits electrically."

 
I know full well what optical coupling is. Hell, my first optical coupling was using tiny incandescent lights and LDRs in a sealed tube!
That still doesn't change the fact that most SSRs are simply NOT SUITABLE to use as you were trying to, across the contacts of a thermostat connected to an electronic control system; nor does any quote from wiki change "optical coupling" (a technique) into "an optoisolator" (a very specific component).
 
Again, you are using the WRONG device for your application, and while you might stumble on something that works from time to time, that still doesn't make it the RIGHT device, nor does it mean it would continue to work under all conditions (temperature, different input voltages etc), and until you understand that, you are going to continue hacking together things that don't work, or work intermittently.

 

[Tschmidt]

incandescent lights and LDRs in a sealed tube!

OT - but boy does does that bring back memories. Had totally forgotten about that form of ancient opti-coupler.
 
/tom

 

[rossw]

OT - but boy does does that bring back memories. Had totally forgotten about that form of ancient opti-coupler.
 
/tom

 
*sniff*. Are you being insulting now, and calling me ancient??   

 

[pittom]

Here is a relay from a hot tub i am working on,will it work with WC or does it need it's own power supply

 

[CAI_Support]

That relay coil requires 0.5W power to operate. You will need to have a transistor or something to run it on a separate power supply.  When relay coil on and off, there is a big electrical spike generated, If not filtered out well, it could trigger CPU watchdog logic to restart.
A good design will include a fast diode to absorb the reverse spike from the relay coil.

 

[pittom]

Thanks i was thinking that there was a big electrical spike 

 

[BraveSirRobbin]

I believe Ross meant to do something as shown in THIS schematic (drive a relay coil with a transistor and EMF kickback diode).

 

[Tschmidt]

It is pretty simple to drive a relay from the WC. One option is to use one of the many buffered relay boards available on eBay. You can also use a solid state relay, there are versions for AC and DC loads but AC is by far the most common.
 
To use the relay you posted just need to use a switching transistor to increase the current capability of the WC and place a snubber diode across the coil to capture the transient generated when the relay is deergized.  Assuming you will be powering the WC with 9V and use a 9V relay in shown in your data sheet it will draw about 100ma. I use 2M3904 transistor for just about all non-critical switching, mainly because I have a bunch of them in my stock. For the catch diode use a 1N4148 or equialivant diode. Want one that is reasonable fast and able to handle the current.
 
 
http://www.fairchildsemi.com/ds/2N/2N3904.pdf
http://www.fairchildsemi.com/ds/1N/1N914.pdf
 
Assuming you do not need any other circutry if it were my design I'd just use an SSR. I'd be a little cautious about some of the electronic on eBay. If you really need 30A I'd spec a somewaht larger relay as some of the Chineese stuff on eBay is subject to creative specmanship.
 
http://www.ebay.com/itm/New-Solid-State-Relay-SSR-40DA-3-32VDC-40A-250V-Output-24-380VAC-w-Cover-/311002079235?pt=LH_DefaultDomain_0&hash=item48692b2003
 
/tom

 

[pittom]

I use SSR relays AC and DC that work very well except on my hot tub one of them get hot and don't have room or enough air flow for heat sink. i was even thinking of using a SSR instead of transistor since i have a lot of SSR,but a transistor and diode is cheaper.
thanks for the help
pittom

 

[BraveSirRobbin]

If I were switching 30 amps, I would use a contactor.  Square D is a great brand.

 

[CAI_Support]

Using a contactor makes sense for large current.  You can use WC board drive a SSR, that in turn drive a contactor relay.
The power lost on SSR is about 0.7V x current (A), If current is 20A, that SSR must absorb 15W or so.  Most contactor relay may use 5W power for coil. Using SSR drive a contactor may save energy and reduce heat on SSR.