Solution to crashing and noisy lines

[SrEngineer]

I have an older OpenSprinkler & expander connected to solenoid valves spread out over 2 acres. The controller has been very unreliable & it was crashing (blank display) every 2 weeks or so.

The expansion board has provision for adding MOV’s which I did. I also added MOV’s to the main controller by adding them to the main terminal board but it was still crashing, so I removed all the MOV’s.

Then I build the control board shown in the picture. Here’s what I did:
1. Removed all the Triacs
2. Jumpered over the triacs so the controller was providing 3.3 volt outputs.
3. Added 2 very inexpensive relay boards with opto-isolators.
4. Wired the control board outputs (3.3 volts) to the relay inputs (opto-isolators).
5. Wired all the solenoid valves to the relays.
6. Powered the relay board with an independent 5 volt wall supply.
7. Powered the OpenSprinkler with an independent 18 V DC supply (careful of the polarity)
8. Powered the solenoid valves with an independent 24 VAC power supply switched with the relays.
9. Added analog meters for voltage and current so I could see what was happening when it was running. I chose analog meters since they are not as sensitive to electrical noise as digital panel meters. They also look cooler, I think.

The 3.3 volt digital outputs from the OpenSprinkler control boards provide sufficient current to drive the opto-isolators
The relays are rated for well over 24VAC and up to 2A and I have a 2A slow-blow fuse in the line.

My new system has been running for many weeks now without any problems.

[Ray]

Thanks for sharing the tip. Sorry to hear that the system was not reliable before. Out of curiosity: do you have a microcontroller-based OpenSprinkler or OpenSprinkler Pi?

[SrEngineer]

I have one of the original microcontroller-based systems. My irrigation system is actually in a pretty ‘hostile’ environment. We have some wires running several hundred feet to valves. There are also many noisy power tools and engines scattered about near wire access points. Plus we have coyotes, ground squirrels, feral cats and other unknown critters chewing off sprinkler heads, pulling up wires and stripping the insulation – sometimes shorting them. They are attracted to the water and the drought makes them aggressive.

I think that I was getting some significant electrical noise coming back on the wires that even the MOV’s couldn’t stop. since I installed the relays, the OS has been running continuously without any issues, so I think it’s solid. The relays seem to be holding up ok even though we have had a couple of shorted wires.

I am currently designing a wireless sprinkler network that will be ‘zero’ power and full monitoring (stuck valves, broken valves, soil moisture, temperature and humidity) and use a WPAN to manage all the sprinkler nodes. These will be used for the ‘far field’ irrigation. It will probably take me 6 more months to get it running.

[SrEngineer]

Is there a way to add pictures? I don’t see any way to do this with the new style.

[Samer]

Currently, the forum does not have its own image upload however any image hosting service will work and linking the image should show the actual image within the forum.

In the future, I will see what can be done (and if it’s needed) about hosting pictures on the forum.

[Samer]

Okay, this feature has been added to the forum. Please let me know if this works for you and if you encounter any issues.

[SrEngineer]

Picture of my control system with relays

Attachments:

1. 

   SprinklerControlBoardSmall.jpg
   

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