I have been reading up a lot on controlling solenoids from the playground and various websites. I want to be able to control my sprinklers from a website.
My solenoids that I need to power has the following specification:
• Solenoid: 24 V ac
• Inrush volt-amp: 24 V ac-11.50 VA
• Inrush current: .4 amp
• Holding volt-amp: 24 V ac-5.75 VA
• Holding current: .2 amp
Is it still advisable to make use of an separate 24V AC PSU and use opto-couplers to switch the solenoids? Or would using transistors be a better option?
Since you are using 24volt AC a Traic would be needed and not a transistor. Traics are used to switch AC devices. Watch this video it has a circuit. I like the MOC3041 because it fully isolates the micro controller from the load. http://youtu.be/5tt4zAkpDPw
Would the MOC3021 also work? What is the difference between this and the MOC 3041?
It's a triac google both part numbers and compare the voltage and current limits etc. You want to use this 6 pin chip to drive a larger current capable triac. http://static.electro-tech-online.com/imgcache/1167-electronique_triac_001e.gif you will not need Q1 since a Arduinio can drive a simple led.