Motion Detector Issue

praondevou

Joined Jul 9, 2011
2,942
It says it has at most 25mA holding current, whereas coil relay power is 2.1VA, i.e. about 17mA. It should be ok if we increase the current to e.g. 50mA to 60mA. Do you have any power resistors at hand that have a few kOhm?
 

Thread Starter

circuitbob

Joined Aug 29, 2011
15
I just moved and don't have any resisters here, tell me what I need and I will get them. I need to do 3 motion detectors immediately and more in the future.

Thanks for your help.

Bob
 

praondevou

Joined Jul 9, 2011
2,942
Two 1k resistors in series each rated 5 to 10W, mounted in parallel with the relay should do it. Best would be to drive the relay directly without the triac so you woudn't waste so much energy but I don't think this what you want to do :).

Also, if you did not yet buy all the motion detectors, consider the one with relay output I posted.

edit :
With 60mA rms, i.e. 85mA peak current, considering 25mA holding current the triac will turn off at 73 degrees (because it's a sine wave).
If for any reason the circuit was designed to give only an initial gate pulse and this gate pulse ends before 17 degrees (or 197) of the sine wave are reached, 60mA rms may not be enough since the current could be lower than the holding current at that point. In this case you would need to increase further the current (decrease resistance). However I don't think they did it this way, the triac should be constantly retriggered.
 
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