Power
There were a variety of power concerns that needed to be addressed in designing this project. First was that the LED arrays had a forward voltage of about 17V. We needed a converter from the AC line that was large enough to accomodate this. Next, the water pumps ran off 12V, so a step down to 12V was needed. Finally, the microcontroller and the sensor ran off 5V, so another step down was needed.
First a 24V 5A supply was chosen to be large enough voltage to provide what the LEDs needed. With 5A there was enough current provided to power the LEDs, the three pumps and the microcontroller.
24V 5A AC to DC converter.
A 12V step down convertor was chosen from Qunqi. This provided an adjustable output which was set to 12V and could provide up to 3A for the 400mA pumps. Since there was three pumps this would insure that all three pumps could be on at once if need be.
12V step down converter.
A LM7805 was chosen for the 5V conversion. This was a quick and easy fix to get the 5V need for the microcontroller and the sensors.
Finally the LEDs need a constant current source to power them. We want a constant current source because we do not want to give them excessive voltage. LEDs can be damaged easily if you exceed their operating voltage by to much. A LuxDrive buck converter was selected from LED dynamics which provides the constant 700 mA to the LED array.
