Greetings.
In the picture below there is a circuit representing a solenoid beeing driven by a switch and a voltage divider. The regulator is a lm7805. My question is..How or can I controll multiple solenoids with one regulator, just using multiple (switch, resistors, mosfet) branches for different solenoids?
[Edit: picture cropped to reduce white space around it. Moderator]
Just using multiple (switch, resistors, mosfet) branches for different solenoids?
Yes.
You don't really need the voltage regulator, just choose the values of the 2 resistors to give you 5V on the MOSFET gate.
If you DO use the circuit as shown the veritcle resistor should be on the switch, not the MOSFET gate. As it is is forms a voltage divider and reduces the gate voltage.
Lose the regulator, the IRF540 needs at least 10V to work properly.
If you need to switch from 5V, you need a logic level MOSFET.
As you are using 12V to turn a 'standard' MOSFET on and off, you don't need the 5V regulator.
That particular MOSFET, IRF540N, wants to see 10V on the gate to turn fully on.
You can make R15 a much smaller value, like 100 ohm, and leaving R16 as 10K and where it is, the gate will see
(12V & 10,000)/(100 + 10,000) = 11.88V when the switch is closed.
The 100 ohm will let the MOSFET turn on nice & fast, the 10K will turn it off pretty quick when the switch is opened.
Thank you all for the help, much appreciated!