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Topic Title: HNC Project, solenoid control problem.
Topic Summary: HNC Project, solenoid control problem.
Created On: 15 April 2013 10:07 PM
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 15 April 2013 10:07 PM
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woody1001625

Posts: 2
Joined: 15 April 2013

Hi all, this is my first ever post on a forum like this so bare with me! I have decided to design and construct a programmable watering device for a domestic lawn as a HNC project. I have selected a (cheap) latching solenoid valve (to preserve battery power) to open and close the supply of mains water to a sprinkler attachment on the lawn, but can't seem to find a suitable controller. It must operate the solenoid instantaneously (as it is a latching solenoid) allow the flow of water for an hour, and then operate it closed again, it will preferably run off a 6v battery, and be relatively compact. The user must be able to programme the time at which this happens. Any help will be appreciated.
 15 April 2013 10:43 PM
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westonpa

Posts: 1771
Joined: 10 October 2007

Have you tried searching programmable solenoid controllers on Google and then take it from there?

Regards.
 16 April 2013 09:06 AM
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woody1001625

Posts: 2
Joined: 15 April 2013

I have spent a while searching on google and component websites etc, but they don't seem to have any that specifically control/operate the solenoid instantly on and off, with it being a latching solenoid. Is there a term used for that instant 'exposure' of power to the solenoid, and do controllers exist where that can be altered ie. milliseconds?
 16 April 2013 08:51 PM
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westonpa

Posts: 1771
Joined: 10 October 2007

If you simply purchased some items of the shelf and connected them together then I doubt you would pass your project. So maybe you will need to look at someone like Maplin and find some components and build your solenoid controller. I would suggest that rather than trying to build a finished item which would exist after manufacture that you build something which could then show it could theoretically be manufactured in a better form. I did something similar for a heating control project. I am not a manufacturer but I was able to build and program something which worked and which could be maufactured into a finished item which of course would be more compact.

Regards.
 16 April 2013 11:12 PM
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peteTLM

Posts: 3217
Joined: 31 March 2005

Do you need to design and build the timer/ programmer yourself or is it allowed to use a off the shelf item for the project??

http://www.electronics-project...ectronicTimeClock.html for a bit of inspiration

http://embedded-lab.com/blog/?p=1378


(not studied these 2 examples above, but you get the idea)

If you can find a suitable timer that gives you an ON pulse, you could always do a simple 555 timer to give you the hour ON duration as a bolt on.


edited to say: if you can use off the shelf- you could always use a cheap PLC controller, but even cheap ones will be expensive for such a purpose. Even a central heating programmer would do.
Regards

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Lack of planning on your part doesn't make it an emergency on mine....

Every man has to know his limitations- Dirty Harry
 17 April 2013 08:55 AM
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benmc

Posts: 26
Joined: 02 November 2012

I maybe getting the wrong end of the stick and I know this will be powered via 12v but maybe look into a Siemens logo kit (plc)
 17 April 2013 09:29 AM
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benmc

Posts: 26
Joined: 02 November 2012

Sorry I was in a bit of a rush before and didn't read your post properly , have you looked at a program called flow code it would be expensive ish to set up but you program micro controllers individually so if your were to "sell" this in bulk it would work out fairly cheap it's easy software to use have a look at it and bear in mind the sell in bulk part note it down in project and explain how it would drive the cost down per unit dramatically ..
 22 April 2013 09:32 PM
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kengreen

Posts: 400
Joined: 15 April 2013

Frankly I think simple is always best. Why design a clock when that job has been done to death. Any cheap but sturdy timer will do. Set it up to trigger a 555 with a relaxation time as desired (easily changed.)

But buffer the solenoid else the inductive kick will wipe out the 555. Possibly use a suitably valued capacitor or a diode across the solenoid or turn it into a constant-resistance network (most elegant solution). I can give you details if required.

Ken Green
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