Hey peeps
I really need some help. Im basically a noob when it come to electronics but I really enjoy making my own stuff and learning along the way.
I'm building a timer box from my high pressure aeroponic system. So this is the basic idea:
My aero setup has 8 12v solenoids, these solenoids must fire all at the same time. They will be powered by an omron timer. The solenoids will shoot pressurized mist for 1 sec every 3 minutes during the "day" interval and for 1 sec every 5 minutes during the "night" interval. The plants roots need less mist during the night cycle so thats why the longer pause duration is used at night, in order to avoid over saturating the roots. (these on and off times for the day and night intervals are just a starting point, more adjustments will be needed based on plant needs)
A PC power supply will be used to power three omron h5cx timers. Each timer is set to work in twin timer mode. The main timer will switch the other two timers on and off. The main timer will be set to 12 hours "day" and 12 hours "night", during the 12 hours of day the main timer will power on the second omron which will be set to 1 sec ON and 180 sec OFF, during the night the main timer will power on the third omron which will be set to 1 sec ON and 300 sec OFF.
Here is a pic of the diagram I made.
**broken link removed**
The solenoids are 12V 0.5Ma each...so 0.5*8 solenoids equals 4A total for the solenoids. My PC PS can handle 16A at 12V.
When I figure everything out I will build a box that will hold all the components.
Here are my questions:
I know I need to use some diodes at the exit lines, just not sure how strong they must be?
A friend suggested I use a relay to avoid having the higher amperage go through the Omrons, any thoughts on this?
In case of a power outage my plants can seriously suffer if the roots are not getting misted at the required intervals. I plan on using a car battery as a back up power source in case the main power goes out. What would be the best way of incorporating a car battery as a back up? Arent they at 15V when full? Would I connect the battery lines directly to the lines exiting the PS?
Also if you have any comments or suggestions please let me know.
I appreciate any help. Thanks