Hey guys (and girls),
I'm making a garden control project, and I was wondering if there are any cheaper ways of controlling the flow of water than solenoid valves. I'm trying to control multiple areas and the cost of the valves really adds up after a while.
Any help is appreciated,
Koop
P.S. I live in Australia, so I can't go to Wal-Mart or anything 
You could make a set of pinch rollers and squeeze the hose shut ??
Maybe the other Aussie's here can help with sources. Big country, not sure who is which part.
CrossRoads, outside of Boston, MA, northeast USA.
Thanks CrossRoads, but if I used that approach, couldn't the pressure in the hose perhaps ruin the motors of the pinch rollers (I'm assuming that you use motors, I have no idea what pinch rollers are, sorry :~), or cause some other catastrophic event?
I was thinking something like a motor with an offset, cam, kind of action. Turns one way and squeezes your hose, turn the other way to relaese.
Put little smarts behind it to know when to stop, like a current sensor - when it starts climbing, the motor is starting to jam, time to stop!
Or maybe a bar that pivots on one end, the other end has a Y that sits between 2 nuts on a threaed rod. You have a little motor to spin the rod and move the level up & down pinching off or releasing the hose.
Or maybe find your local washing machine, or refridgerator, company, see if you can get some solenoid valves from them?
For example:
I guess I could use one of those valves - after all it only comes down to about $11.05 per valve on Amazon! Thanks for your help, CrossRoads!
Regards,
Koop
Just thinking outside the box for you mate 8)
I haven't looked for ages but solenoid valves from places like Bunnings aren't that expensive are they?
BTW, it's VegEmite, (I had to go look at a jar to make sure :))
Rob
To Greynomad,
I did check on the Bunnings website (I haven't been in store) and the cheapest ones were $19.92 (and Australian made; YAY!) which, to me at least, is a little too expensive (Feel free to call me a cheapskate). So I'm going to add the P&H to the total for the Amazon valves (Look here: http://tiny.cc/z9d7h) and see how much it is. I mean, if you compare the $11.05 per valve on Amazon to the $19.92 from Bunnings, the savings really add up (As the woman from the NRMA ad would say ;)). By the way, I will have to fix that up. I really should know this stuff :P.
To CrossRoads,
Was that an attempt at Australian colloquialism there?
That Amazon valve looks to me like it's a mixer, ie hot and cold into a single output. If that's the case is that what you need? It's not normally the sort of thing used for garden control.
Rob
Oops! I didn't notice that, so I'm glad someone did! Although, it's probably likely that I can cut off the valves before they mix, creating two separate valves. I'm just wondering: should I risk it?
I trust you could look at them as one inlet with two outlets and so not an issue. They seem to come with push-to-lock fittings however (and different sizes at that) which may be more of an issue. Unless this is what you need, you may end up spending more on fittings than you would on the valve itself.
Here are a couple alternatives:
http://www.seeedstudio.com/depot/electric-solenoid-valve-p-636.html?cPath=156_160
should I risk it?
I would say no. It's hard to see with that photo but I would expect only a single outlet and there would be no practical way to separate the valves.
Another thing to think about is the control voltage, anything made for a fridge will use mains I reckon which is more difficult to work with, and if you get it from the US that will be 110v.
Personally I would not buy anything from somewhere that didn't provide a full data sheet and in this case mechanical drawings. Maybe you can get these from GE.
Have a look at this
Small ports but they might have larger versions.
Rob
Why not simply visit your local junk yard and strip some valves out of scrap washing machines, dishwashers etc
They will typically be mains AC operated so you'll also need a bunch of interfacing devices, whether they be relays, SSRs or triacs.
Wow. I got a lot of replies while I was out for dinner, so I'll address each person individually.
Firstly, to Greynomad. As soon as I clicked on the link and saw the picture, I realised that I had seen these before in the latest Jaycar catalogue during my previous searches! Unfortunately, I dismissed these a long time ago because of two reasons. One, the inlet/outlet valves were too small and the don't come in larger sizes, and two, what the Jameco website doesn't say is that the valves are for air only, not water (See here: Telegram: Contact @byprodigy) 
So those are out of the question, but thanks anyway!
Next, to Jackrae. While your contribution is appreciated (As are everyone's), I don't see your idea working in my setup, simply because I don't think that having 240VAC (Australian mains power) so close to water is a good idea. Also, while getting them from the junkyard would be a cheap option at first, I would then have to get power supplies, chunky relays and etc. This is an unnecessary cost when I can just power the solenoids with the same power that I use for the Arduino. So these, once again, are an unlikely option. Thanks, though!
Last, to BenF. Your first comment,
I trust you could look at them as one inlet with two outlets and so not an issue
does make sense at first look, but is most likely incorrect. Companies like GE rarely make it easy for us hackers (I don't know why :)), and would have probably put a one-way valve somewhere inside the solenoid to make sure that there is no back-flow. However, the links you gave me made me want to cry with joy (Not really, but I was very happy ;)) because they provided just what I need. I'll probably go with the ones from Seeed Studio, simply because I need good solder connections, not screw terminals, and also because I don't think that it would be easy to find a screw-on valve connector like that. But I think that you may have solved my problem!
Thanks to all of you for helping me with this!
Actually, while we're at it, does anyone know where to find Plaster of Paris in Australia (Sorry to be dragging it on!)
Koop:
I trust you could look at them as one inlet with two outlets and so not an issue
does make sense at first look, but is most likely incorrect.
It was not a speculation on my part, but based on the product description with its reference to one inlet and two outlets.
WR57X10032 Product Specifications: 1/4" Compression Inlet * 1/4" and 5/16" Outlet John Guest Fittings
Oh, sorry. I didn't notice this when I had a look at it :). But I still think I'll go with the Seeed Studio solenoid simply because it is cheaper. Thanks though!
does anyone know where to find Plaster of Paris in Australia
Maybe art supply shops.
Rob
Oh, OK. Thanks!
Koop,
Yes it was 
Refridgerator ice makers use single valves, if the washing machine valves or others don't work out.