Hello, I'm an electronic hobbyist and am having a problem trying to figure out how to interface a circuit that I found at RED Free Circuit Designs. The circuit is called Plants Watering Watcher and uses a varying brightness LED to signal the necessity to water a plant. You can view the circuit at
www.redcircuits.com/Page18.htm, I'm also including the circuit as I re-drew it in an attachment. The circuit outputs a square wave having a variable mark-space ratio which lights a led to indicate when a plant needs watering. I would like to take that signal and feed it into an input of a analog to digital converter of a 16F877 microprocessor to turn on and off a pump to water the plant. I just figured out and wrote the code for the ADC using PicBasic Pro and it works great and now I have to find a way to interface it to the micro. I think this would be a great project to put together, for when I go on vacation to water my house plants. Is there an optoisolator chip that I could connect to pin 10 of the 4093 that would give me a clean positive output that I could use to connect to the micro's ADC input? Can anyone here point me in the right direction as to what type of converter that I will need to design to interface to the micro? Would an op-amp work or? Any help will be greatly appreciated. Thanks...........jessey

Attached Images

The_Circuit.jpg (113.8 KB, 549 views)