Hi,

I have a motion sensor that has a dry contact relay output. The contacts close when motion is detected. The photo is the inside of my sprinkler controller. I want to run a wire from the 24 vac screw to one side of the relay contacts and then from the other side of the contacts to the screw for zone 8. I want zone 8 to work by the program and or the motion detector relay. If zone 8 is on from the program and then the sensor contacts simultaneously, will this be a short or a back feed into the controller issue?

 

In normal operation, the controller pictured would put ~24V onto the blue wire at #8?

If so I'm thinking it would be safer to OR the two power supplies together by placing a diode on both before the blue wire. So you'd have two power supplies, the controller and your relay contact, each with a diode forward biased towards the blue wire. The diodes prevent current flowing from one source to the other.

They will drop voltage a little (~0.7V give or take depending on the specifications) but I doubt that's of concern in a 24V system. Easy to test that assumption.

If you have any information on the controller's internal circuitry, it's quite possible that the output is already protected internally by a diode to prevent back current.

Oh crap, we're talking about AC not DC. That may still be OK. Are the output voltages such as on #8 also AC or have they been rectified to DC?

 

It is my understanding that there is a water valve from COM to 8 as shown in red.
I think there is a Relay shown in green. I am not certain which side of "24VAC out" the relay attaches to.
I think there is a short from COM to COM to COM and probably to one side of "24VAC out". I do not know which side!
Place the motion sensor contacts from 24VAC to 8. I think it is that simple.
Do you have a voltmeter? We should test something first.

 

We do not have adequate information given. We have one reasonable guess. I do not offer advice based on guesses, unless I qualify it as a guess.

 

It is my understanding that there is a water valve from COM to 8 as shown in red.
I think there is a Relay shown in green. I am not certain which side of "24VAC out" the relay attaches to.
I think there is a short from COM to COM to COM and probably to one side of "24VAC out". I do not know which side!
Place the motion sensor contacts from 24VAC to 8. I think it is that simple.
Do you have a voltmeter? We should test something first.
View attachment 364459

I have a volt meter. Each ac valve solenoid is controlled by a triac.

 

In normal operation, the controller pictured would put ~24V onto the blue wire at #8?

If so I'm thinking it would be safer to OR the two power supplies together by placing a diode on both before the blue wire. So you'd have two power supplies, the controller and your relay contact, each with a diode forward biased towards the blue wire. The diodes prevent current flowing from one source to the other.

They will drop voltage a little (~0.7V give or take depending on the specifications) but I doubt that's of concern in a 24V system. Easy to test that assumption.

If you have any information on the controller's internal circuitry, it's quite possible that the output is already protected internally by a diode to prevent back current.

Oh crap, we're talking about AC not DC. That may still be OK. Are the output voltages such as on #8 also AC or have they been rectified to DC?

I believe the valve solenoids are ac I will check that tomorrow.

 

All of the sprinkler valves that I have seen use 24 volts AC power. Probably they could work with hals-wave AC also.
IT seems like the goal of the TS is to also operate the water valve when the motion sensor sees motion. An interesting application.

If that sprays a mail carrier cutting across the lawn, there may be "an issue arise"! In the US, mail carriers are federal employees, and protected quite seriously.

 

All of the sprinkler valves that I have seen use 24 volts AC power. Probably they could work with hals-wave AC also.
IT seems like the goal of the TS is to also operate the water valve when the motion sensor sees motion. An interesting application.

If that sprays a mail carrier cutting across the lawn, there may be "an issue arise"! In the US, mail carriers are federal employees, and protected quite seriously.

Thats who I was targeting!

 

My letter carriers walk across everyone's lawns. This means they come across my driveway, up my porch from the south, drop off mail, exit the porch from the north west stairs and walk the same path across my lawn. There's always a worn foot pathway where they trod and it bothers me. I've been thinking about making a walkway where they usually trod.

I'd adhere to @MisterBill2's advice.

 

My thoughts of such a device is to spray stray cats who come into my yard and drink from my fish pond. Once I found a dead fish outside of the pond. But that's off topic.

 

I have a volt meter. Each ac valve solenoid is controlled by a triac.

"triac" indicates it is a 24Vac system. Most common.
Measure the AC voltage from COM to one of the AC OUT. I think one will read zero and the other will read 24Vac.
If this is true, then you can try jumping from the 24VAC to 8 like in post #3. Number 8 should turn on.
Often these boxes have a low voltage fuse in the box somewhere.

I did something like this for the Dog in the flowers problem. I set the time for very short, maybe 10 seconds. There are some boys that come by every month on Saturday, in white shirts. They want to save me.

 

"triac" indicates it is a 24Vac system. Most common.
Measure the AC voltage from COM to one of the AC OUT. I think one will read zero and the other will read 24Vac.
If this is true, then you can try jumping from the 24VAC to 8 like in post #3. Number 8 should turn on.
Often these boxes have a low voltage fuse in the box somewhere.

I did something like this for the Dog in the flowers problem. I set the time for very short, maybe 10 seconds. There are some boys that come by every month on Saturday, in white shirts. They want to save me.

Thank you, i think I got it, i was surprised that the left screw under the 24 v a c label was the common. I decided to use this relay, it's coil will be powered by the photo sensor which hasn't arrived yet. Relay COM goes to solenoid, NC to term 8 and NO to 24 vac hot.

And thank you for not commenting on my letter carrier.

 

I was just thinking; any spraying system to spray a cat away will come with a lot of sprinkler noise prior to the water coming out of the sprinkler. The hissing noise would probably chase them away.

 

An oldie but goodie for inspiration:

 

An oldie but goodie for inspiration:

Is there a thread on this subject?

 

inspiration

Watch the last one minute. In the credits. Big boy marking his area.

 

Is there a thread on this subject?

I think I've probably provided that link at least once here before. Don't recall where.

 

I have a volt meter. Each ac valve solenoid is controlled by a triac.

Since it looks like the water valve solenoids are connected between each relay contact and the "common" circuit, a very logical guess is that the other side of the 24 VAC supply is connected to the other relay contact. That wouls be the "controls engineering" way of doing it.

 

Is there a thread on this subject?

When I searched on the Youtube video number uIbkLjjlMV8, I found that I've provided the link many times but the kudos go to @SgtWookie for first posting it:
https://forum.allaboutcircuits.com/threads/how-to-stop-cats-from-peeing-on-your-car.57247/