Irrigation / sprinkler valve

narced

I would like to control a standard irrigation valve from a microprocessor. Has anyone ever controlled an irrigation valve? I think that they are 12v devices, and are bipolar. This leads me to believe that a standard h-bridge should do the trick.

Any suggestions for easy to find h-bridges or good transistors and circuits for making my own are appreciated.

Thanks!

- narced

Franklin

The ones I've seen at the "Depot" seem to be 24V solinoid operated. If you have a different source I'd like to see them as it would take a load off the processor not to have to keep the valve open. (I know I could use a flip-flop to do that but the thought came to me after I had this typed and I'm a really slow typer and didn't want to waste what I had) [noparse]:)[/noparse]

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- Stephen

Philip Gamblin

Yeah I just did this with a Depot sprinkler valve. All the sprinkler stuff I found was 24v AC. I used a 24 v center tapped 2.5 amp radio shack transformer,rectfied 1/2 of the secondary to supply a 12 volt relay that I switched with a 2n2222a. Not difficult but the wiring can get messy if point to point. The valve seems to need the water as a motive force. I could not blow through the valve with my mouth but it seemed to function fine with water. Not a real snappy operation but functional.

Post Edited (Philip Gamblin) : 7/1/2007 4:51:46 PM GMT

Larry

The standard in the industry is to run them at 24v AC, but I think most will run fine on DC current.
I've run both Orbit and Toro models on 18v DC from a Ryibi portable drill, and I've heard of Pneumatic spud guns that were triggered with two 9v cans batteries in series.
Never tried thatmyself, though.

Running them on DC makes triggering easy- just use a TIP 120 or a FET.

here's a system thats rated as DC www.mrdrip.com/timer540000.htm

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skylight

I've had·experience in the past with running AC devices such as solenoids or relays from DC sources as after a time the core becomes magnetised and have had relays stick on or solenoids not returning after power off.

Philip Gamblin

Larry, those are nicer valves that the Depot stuff. From the valve looking arrangement on top they also appear to be adjustable flow rate as opposed to simply on/off.

narced

So what you guys are saying is you just apply 24 volts and the valve is held open. Remove the 24 volts and it springs closed? No need to reverse the voltage?

- narced

Philip Gamblin

Yes that's correct. Only they tend to take .5 secs. or so to open and close. It's not the snap action of something like a relay.

Larry

narced, That's correct, Power on==> open, power off close==> closed. There's a spring return. And it doesn't matter the polarity, in my experience. I also noticed one of the solenoids I have was a Genie, so that's also one that will work on DC. If you have a power tool battery around, touch the leads to it and see.

Skylight, As far as magnetizing the cores, I haven't had that problem. I suppose you could if you have a higher duty cycle than I've used, But I don't know. You might just try reversing the leads periodically. What kind of time span and use are you talking about? If it was over a few years, it still might be cheaper to rplace a solenoid occasionally than buy a bank of h-bridges. I've had to replace one 'cause it cracked form age or frost.

Philip, How can you tell the solenoids are any different? I've bought valves at HD with manual shutoffs (turn on, actually, remove the mechanism and they stay shut), if that's what you want. It was a few years ago, though. You might have to buy manual valves and a solenoid conversion kit.

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sam_sam_sam

narced

The one that i used are the Toro solenoid

You can run these valves on DC current
I·found·the solenoid ran at 7.5 volts DC·@ 230 milamps

The problem that i saw was that the current went up as·I put more voltage solenoid and was getting some what warm
so i just ran them on my power supply· at 7.5 volts DC

·I just put in my sprinker system and this is how i tested·each zones that i was putting in with the power supply before I hook up the controler
that i bought

I hope this helps you in what you want to do

I would run them on AC current and a soild state relay·I think it would be easyer to it that way

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··Thanks for any··that you may have and all of your time finding them

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Sam

Philip Gamblin

Larry , I wasn't referring to the solenoid but rather the actual valvebeing different. I was also surprised to find at HD replacement solenoids and cheap too.

Shawn Lowe

I can't believe you can run a AC solenoid off DC, but for the life of me, I'm a little tired, I can't see why not. You can acually do this?

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Shawn Lowe


My last words shall be - "NOT YET!!!"

Larry

Somebody said...
I can't believe you can run a AC solenoid off DC, but for the life of me, I'm a little tired, I can't see why not. You can acually do this?

Why not? it's just an electromagnet. I think the original surprise for Edison was that you could run such things on AC.

There are all sorts of devices that will run fine on DC. some examples--light bulbs, pumps, and power tools(I'm talking the kind you plug in).

When I was in college in the 60's, I once rented a farmhouse from a farmer who used DC current off a tractor to run Skil saws and power drills when he was out about his property. Inverters were pretty expensive, then.
When I asked him about it, he laughed and said that until about 20 years before that, all the local service from the farmer's coop was DC and most stuff ran fine. I'm not sure that's the case, anymore. I wouldn't try doing that with a microwave.

Actually, there is one reason not to use DC I've heard from someone who installs irrigation systems--apparently with underground cables, there's a greater chance that current leakage could cause galvanic damage to wires or nearby burried metal objects, especially galvanized pipes. I know that was a problem with Old electric trolley systems if the track continuity was poor.

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narced

Larry said...
narced, That's correct, Power on==> open, power off close==> closed. There's a spring return. And it doesn't matter the polarity, in my experience. I also noticed one of the solenoids I have was a Genie, so that's also one that will work on DC. If you have a power tool battery around, touch the leads to it and see.

Great! Thanks for all the input guys.

- jason