Hi there. For my science fair this year I'm doing a controlled environment for plants using the arduino uno. I want to be able to turn on a fan when the temperature gets higher than the set temp also I want to have it turn on leds at a certain time and have it water plants at three set times a day. How would I be able to do that.
I already have the fan its a 12 volt pc fan
I'm thinking of using a pump hooked up to a relay for the water system
Any good design is "fail-safe", and this becomes especially important when water is involved.
Ask yourself what would happen if the water pump got stuck on.
One fail-safe design:
Plant on tray.
Tray over larger container, which serves as resevoir for water.
Water drawn from that resevoir by the pump.
If pump gets stuck "on", then when the tray under the plant begins to overflow, if everything is arranged correctly, the extra water just falls back into the resevoir.
Two benefits:
Your home doesn't get flooded.
The pump doesn't get burnt out from trying to pump air when the supply runs out, which it won't (in the short run) in the arrangement above.
Of course, the resevoir must be "topped up" from time to time, to replace water lost to the air through the plant's leaves.
If you use this and are giving credits in your science project, please credit...
"http://sheepdogsoftware.co.uk
Source of educational freeware and sharware"
Source of 12v pump: Auto parts store. (Windshield washer pump) Some do not self prime nicely. With those, you have to mount them at a level lower than the top of your resevoir, and ensure that backflow when the pump shuts off doesn't "de-prime" the pump.
OK I will use that circuit. For powering the fan I have a 200 watt at pc power supply
Probably quieter as well.
I've received some nice supplies from these guys.
http://www.mpja.com/prodinfo.asp?number=18520+PS
I am using this 5V/4A unit in a project right now, with a 12V/2A boost regulator from pololu.com for driving banks of LEDs in series.
That same 12V also goes out 2 different lengths ~30' of wire to drive more LEDs on each end and gets regulated by a 7805 to power 2 minipros.
And no fans. Doesn't even get warm.
http://www.facebook.com/photo.php?fbid=121266371275990&set=a.121266354609325.19589.100001778820478 heres the link to my simple sketch
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