Now this is fun. Bought an Arduino / Sparkfun  UNO experimenters kit from Little Bird Electronics. Talk about easy to get running. The little workhorse is now driving the irrigation system in both the upper and lower greenhouses. Here is a pic

I built a 240V -> 24VAC transformer into a jiffy box – its 72VA so I added a 6A fuse. This drives the bodgy little power supply on the left and is switched by the relay into the . 24VAC becomes 12VDC and this then drives the Arduino and the relay. The heatsink on the 7912 voltage regulator is an old Pentium 1 heatsink. Most of the wiring on the breadboard is to

  • accept input from the single switch which either starts or stops the timer
  • drive the piezo which plays a small tune on water on and off
  • drives the servo on the right which provides visual indication of the timer cycle
  • drives the flashing “power (yellow)” and “water on (red)” LEDs
  • holds a single transistor to drive the relay

This is the business end

$19.50 24VAC solenoid from Bunnings and some poly pipe fittings. This irrigation setup is fed by a tank and the valves work OK with this pressure. The fine solenoid cable back to the Arduino is just inserted 100 mm underground using a spade to cut the turf and (this is important) a “stick” to shove the cable to the bottom of the cut. Its not really terminated with insulation tape, there is some soldering and heat shrink under that.

At the moment the Arduino is simply turning it on for 15 minutes every 11 hours and 45 minutes. Future improvements will include

  • A more permanent board for the interfaces
  • LCD for cycle indications
  • A RTC (real time clock) for timing.
  • More relays for different circuits. I need to connect Jacq’s staghorns on the eastern deck into regular watering.

Most of this, of course, is dependant on me not sacrificing the Arduino into the next project……   THIS! Muah-ha-ha