I'm working on a project that uses an arduino uno board to pump water, but I've been facing some issues in choosing the appropriate materials that are also available where I live. The project uses a 5-6 V peristaltic liquid pump with motor current 500 mA. This pump is unfortunately not an option for me but I found a mini submersible water pump 3-5v with 180 mA current. I also found an R385 DC 6-12V pump with 500-700 mA current. The project also uses an IRLB8721 transistor that is unavailable where I live. These are the available transistors: 2N7000, IRFZ44N, IRFB3607, IRF840, IRF830, IRF730, IRF640, IRFP260N, IRF530, IRF3710, IRF1010E, FDA50N50, IRFU9310, FDA24N40, 12N60, IRF520, IRF3205, IRF9530, IRFP250N, IRFP150, IRF740, IRF4905, IRLZ44N, IRF9540, IRF540.
My questions are: can I use on of the 2 pumps I listed instead of a peristaltic one? Which of them is the best option? Would I have to buy extra materials or change the transistor if I use the 12v pump? Also would I have to change the materials for the submersible one? And which transistor can I use instead of IRLB8721? Would I need any extra materials if I use a different transistor?
If you wish to use a MOSFET, check the data sheets and use one specified as logic level, for example IRLZ44N.
If using an NPN bipolar transistor, check the data sheets and use one that can handle the stall current of the pump (typically 5 to 10x the free running current).
Don't forget the gate or base resistor, required to protect the port pin from overcurrent damage.
Here are the drawings for @jremington's suggestion. If you use a MOSFET and if you are concerned about it turning on during reset or similar conditions, place a 10k resistor from the port pin to ground. Make sure not to place this resistor directly on the gate.
Additionally, you can add a flyback diode across the load to protect against voltage spikes. Connect the cathode (the side with the band) to the positive supply (+).
You can use either circuit for any of the pumps you mentioned, as long as the chosen component (BJT or MOSFET) is rated to handle the required current and voltage.
You only tell you pump water. For what? What flow you need? Pressure?
The second pump has almost 10x power compared to first one...
What power supplies you use/have?
If your submersible pumos are centrifugal pumps, they will have a very limited pressure, so they cannot bring your water very high...
With peristaltic pumd that is no problem.
Keep them submersed. They will not suck water unless the house is filled with water...
Don't let them run dry. Water is the lubricant and will take the heat away...
