+1 on the price gouging. Automated grow equipment is a complete ripoff. Period. I realize there is SOME increased costs involved in manufacturing electronics for the general public, but the fact of the mater is that the price of IC's and electronics components has fallen off a cliff. Since the mid 90's (roughly) there has been a huge increase chip production technology, and prices have been falling steadily ever since (you know... the whole Moore's law thing). Consequently, there is absolutely no excuse for some of these companies charging what they do for grow room automation gear. Really it's not just automation gear, its the whole "Home Gardening" industry but I won't get into that. For example... here is an idea of the cost of the more expensive parts used in automation systems....
$19.99 -
CO2 Sensor This one is on the top of my list, and appears to be plenty accurate enough.
$1.50 -
Photo Cell - Sensor outputs a voltage when exposed to light. (Used for detecting when lights are on)
$15.99 -
Gas/Liquid Solenoid This solenoid is normally closed and handles up to 140 PSI, which should be plenty sufficient for controlling release from a small CO2 tank. Like this...
$59.95 -
Reconditioned 5lb CO2 tank
But wait... you want to control fans, lights, pumps, etc? Then you need a
$2.61 -
Power Relay It's rated for 10A @ 240VAC. Thats roughly 2400 Watts, which is 20Amps at 120VAC. That should be plenty powerful enough for some pretty large devices.
So how do you read the sensors, control output devices(like a relay), and log data over the length of your grow? Plug 'em into a Microcontroller; like an
Arduino or similar system like
Phidgets. This is the step that discourages most people. In reality though, it's relatively simple. With the creation of newb-friendly microcontroller development platforms like the Arduino it has virtually become a Plug 'n Play activity.
For those who are interested, check out this
link. It's a tutorial on how to use a relay to control a 120V wall socket. Reading that link is where I got my start. Just imagine... complete control over every single parameter of your grow and the ability to record all those parameters for analysis, tweaking, and maximize results!