I am quite lost when it comes to choose the mosfet i think i need.
So i currently have a arduino that controls a little perisaltic pump (X5) to water my plants.
That works well except that i use a relay to turn the pump on/off.
I would like to change the relay for a mosfet that would probably be smaller and generate less noise that (i belive) impact my moisture sensor.
I just do not understand how to choose the mosfet i need...
Choose the transistor based on the stall current of the motor. The stall current can be several times the running current. The stall current should be listed in the motor data sheet. If you have no data sheet it is possible to estimate the stall current, measure the motor winding resistance. Take several measurements rotating the motor a bit between readings. Use the lowest reading in the calculation. The estimated stall current is the motor supply voltage divided by the measured resistance.
You need a logic level MOSFET. That is a MOSFET that can be fully turned on by a logic level signal (5V for a 5V Arduino, 3.3V for a 3.3V Arduino). You can tell a logic level MOSFET by the Vgs specification in the Rds(on) specification. The Vgs should be logic level signal voltage or lower.
Do you want surface mount or through hole package?
Thanks for all the answer,
I use 5v Arduino
i have no data sheet. Took my voltmeter and i got between 2.2ohm and 1.9 ohm on the motor. so the stall current would be 3V ?
Also they all have sevral RDS on the file LarryD provided how to choose the 5v one?
On paper IRLML2402 looks good, it has RDS on 4.5V and can take 1.2A...
Because it's not a MOSFET. It's a Darlington transistor. You could use it as well, but it is conceptually different from a MOSFET; a Darlington is basically two NPN transistors, one piggy-backed to the other. It can work in your setup, but a MOSFET is slightly more straightforward.