I am thinking about my next project and I would like to make an automatic watering system for plants. Because I would like to cut down costs, I was thinking about having a single water pump for the whole system and use electronic valves for each plants (because they will not all need watering at the same time).
What kind of pump should I choose? Is there such a thing as a 5V water pump or are they all 12V and I will need a 5V to 12V relay?
What about the electronic valves?
What about the max tubing length? And diameter? I am pretty sure there is a way to calculate all that but I have no idea how.
There are many 12V pumps. So you have a lot of pumps to choose from.
There are 5V pumps ment for battery operated devices. But they might not be very reliable.
A relay is more expensive than a transistor or a logic level mosfet.
If you use a transistor or logic level mosfet, a diode is needed.
Or you could use some solonoid or motor driver ic.
How high the water can be pumped up, depends on the pump.
Check Ebay for "water pump 12v dispenser", or "water pump 12v car".
The tubing diameter could be small (even a few mm, or 2/10" would be okay) and the tube can be long (many meters). I suppose you don't need a lot of water at once. The most important thing is, how high the water must be pumped. If you need to pump the water to the second floor, you need a stronger pump, stronger valves, and even stronger tubes and connectors.
I have made a automatic watering system with 10 solenoid valves and a small 12v pump (2A 7,5 l/min).
For the pump I use a relay and for the valves I have 2*ULN2803A transistor arrays.
I also use 2*74HC595 shift registers to control the ULN2803A (for saving output pins).
The valves is opened one at a time to keep the water pressure high. The system works like a charm, I can control watering by different schedules (days, hours, which plants that should get water).
Here is a picture of the valve I use (common on ebay).