Electronics > Beginners
First time with mosfets, am I doing it right? (wireless irrigation system)
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namero999:
Hello all (and sorry, english is not my native language).

I'm working on a personal project, an automatic watering system. It has the following features:
- esp8266
- analog and i2c ports for sensors (such as temp and soil moisture)
- port for water pump (250mA @ 5V)

In front of the whole thing, I'm putting a soft latching on/off switch, as described in this eev video



I attach the schematic, where I divided the circuit in logical components (the relevant one being Power and Pump, where the 2 mosfets are circled in red).



My questions are:
- is it correct to have a mosfet piloting the main power and one piloting only the pump?
- how can I calculate the current draw of the soft latching on/off circuit? I'm afraid I can't see how much current will pass through it when the pump (or pumps!) will be on, therefore I'm not sure what components I should choose to implement it.

Thanks, generally speaking if you have any feedback on the schematic I'll appreciate it, I'm a beginner on these topics.

Best regards.
Arjunan M R:
Which MOSFET are you using for Q4?
namero999:
I still have to decide but I think this is my candidate https://www.mouser.de/datasheet/2/308/NTR1P02T1-D-100317.pdf
Arjunan M R:
Also, how much current will the pump draw? The maximum continuous drain current of Q1 is 750mA.
namero999:
The pump draws 250mA @ 5V and the reason why I chose the 750mA is because I might opt to have multiple pumps (2 or 3) attached to it.
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