Problem - Open Collector output to a negative trigger relay not working

[pete_c]

Yup; here I see you mention that the 12VDC load from the AC to 12VDC transformer never changes. 
 
Here I wanted the doorbell  / zone to change even if there was no power in the house; which really doesn't matter much I guess.
 
I do also utilize outdoor front door motion (multiple different ones) and doorbell triggers on the panel (which does some CCTV stuff).

 

[RAL]

Fail -  it's operating intermittently. 
 
I'll meter it and see what is going on.

 
I've been talking about this problem with a friend, and we debated whether adding a pullup resistor to the trigger input might help.  His thinking is that the 11V you measured there with nothing connected might just be due to leakage current, and that the input really needs a pullup to reliably detect a transition.  Adding it certainly won't hurt anything, so there's nothing to lose except a little time by trying it.
 
It shouldn't matter too much what value resistor you use.  Something in the range of 1K  to 4.7K should do just fine.

 

[JimS]

Desert_AIP, on 29 Aug 2014 - 10:26, said:
I have a small 24VAC to 12VDC voltage converter hooked up to the doorbell transformer to power the relay board.
I don't think that's the problem, even when the transformer is under load from the doorbell solenoid the 12VDC voltage readings are still stable.

Is the doorbell transformer output 24VAC? Many are around 16 VAC. Which could be giving less than 12V output under load. You say the 12VDC is stable but perhaps it is dropping when the relays also try to energize. I would try a different 12VDC supply. If nothing else, at least you can rule out this as the cause. And make sure the common (negative) of supplies are connected together so all the components have the same voltage reference.

 

[Desert_AIP]

I'll double check the voltage.  I think I metered the transformer at 20VAC.
I definitely metered the 12VDC under load and it stayed the same.
 
I had thought about the pull up resistor too.
I used a 10K resistor, that might have been too high, or I may have connected it wrong.
I was thinking the negative trigger pin to the +12VDC terminal.
 
For now I wired in a relay from the 930 to provide dry contacts to the delay board.
You should see all the electronics stuffed into my doorbell case! 
That works reliably and I need to move on to another project.
I still want to come back and tinker with this thing, just to understand it if nothing else.
 
Thanks for all the help.