Hi,
I want to hook a sprinkler valve up to a motion detector.

The motion detector (Heath Zenith SL-5316) will put out "up to" 500W, and 4.2A (120 VAC).

The sprinkler valve (Orbitz 57020) requires 18VAC min, but is spec'd at 24VAC to draw 0.35A when it switches and 0.23A when it is holding.

How close to this actual output current do I need my transformer to be? I'm concerned about the "up to" nature of the motion detector, will I need to put a load resistance somewhere to avoid overloading the sprinkler valve? Is it possible the motion detector will overwhelm the transformer if it doesn't see a high enough load? I'm a bit rusty on transformers...

My application is to scare cranes away from my koi pond by spraying the area with water...

Thanks so much,
Marc

Quote:

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Originally Posted by mchriste

Hi,
I want to hook a sprinkler valve up to a motion detector.

The motion detector (Heath Zenith SL-5316) will put out "up to" 500W, and 4.2A (120 VAC).

The sprinkler valve (Orbitz 57020) requires 18VAC min, but is spec'd at 24VAC to draw 0.35A when it switches and 0.23A when it is holding.

How close to this actual output current do I need my transformer to be? I'm concerned about the "up to" nature of the motion detector, will I need to put a load resistance somewhere to avoid overloading the sprinkler valve? Is it possible the motion detector will overwhelm the transformer if it doesn't see a high enough load? I'm a bit rusty on transformers....

My application is to scare cranes away from my koi pond by spraying the area with water...

Thanks so much,
Marc

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the motion detector won't do damage to the transformer( too big of transformer will damage detector)... get transformer with a10- 18 W supply... that valve take about 8.5 w

No matter how big of a transformer you put in, it will only draw the power the valve draws plus its winding resistance. So the common cheap furnace or Radio Shack 24 volt transformers should work fine.

Hope it works, those cranes can make a mess.

Not sure if I understand This detector,
I would wire like this:
Switched leg from detector to one side of transformer(line side), other wire, line side
Of transformer to neutral. Secondary side of transformer to valve(both wires)
Transformer will not have increased load. And detector can easily handle load of little
24 volt transformer.