Automatic Watering System

[solution]

Hi

I'm in a plant growing competition. I'm not allowed to buy an off-the-shelf watering system, but it occurred to me today that it may be possible to build a simple timing circuit that could dispense the water when I am not there. I have done a web search and found the following: -

http://www.reuk.co.uk/Repeat-Timer-Circuit.htm

which seems ideal as I would be looking for something that would be on for ~5 seconds every couple of hours.

The only constraint is that it must be battery-powered.

Here are my questions: -

1. How realistic do you think this is?
2. How much would this cost?
3. How long would it take?
4. Where could I find a water valve that can be triggered by a potential and then closed? (I live in the UK)
5. Do you have any circuit diagrams of something suitable?

Part of the reason I want to do this is enjoyment, but if you can see a simpler solution please let me know. I have also considered buying a Raspberry Pi as programming is not a problem for me, it would just be more expensive and I'm just not sure if it would run off of a battery for many days at a time.

Thank you.

 

[CocaCola]

[*]How realistic do you think this is?

Very, as long as you put the effort in...

[*]How much would this cost?

The biggest cost factor will be the valve, if you use one... Either way not too expensive...

[*]How long would it take?

You could likely build it in a few hours time, design and leg work might take a few hours to a few days...

[*]Where could I find a water valve that can be triggered by a potential and then closed? (I live in the UK)

I would likely pick one up on Ebay, you want what is called a solenoid valve... I would source one that is 12 VDC or less to simplify things... Sound be under $20 US...

[*]Do you have any circuit diagrams of something suitable?

Someone with more time might be able to work one up for you, but my time is kinda short right now...

I would personally just use a micro to time the pulses, but a pair of 555 timers is likely better for the newbie, one to time the down time and one to pulse the one time, this allows for more flexibility in the timing, you would control the valve with a transistor&relay...

Part of the reason I want to do this is enjoyment, but if you can see a simpler solution please let me know.

You could skip the solenoid valve and on tap water and use a bilge/fountain pump in a bucket/tank of water...

I have also considered buying a Raspberry Pi as programming is not a problem for me

Unless you luck out delivery and wait times on them is still in the weeks or months...

 

[solution]

Thank you CocaCola.

I'm sorry I'm using your time. I've just wikipedia'd the solenoid valve and I understand roughly how it works and I think I've found a suitable one on ebay as you suggested: http://www.ebay.co.uk/itm/12V-DC-1-...ial_Automation_Control_ET&hash=item43a8b73d78.

I have another question I should have asked before: -

• I plan to power this with 8 AAA cells in series. Neglecting the power drain from the circuit; and with the valve only open for 5 seconds every hour; I estimate this will run for aproximately 140 days. Does this sound about right?

(I've assumed it uses no power when closed)