Hi,
I made this Mosfet circuit to control a solenoid and I was wandering if I could use it for controlling the speed of a DC motor as well? The DC motor will be either 12V or 24V.
Will it work?
Can I avoid the octacoupler or better to have it?
Thanks
The max Vgs (voltage, gate to source) for FQP30N06L is 20V, your schematic puts 24 on it.
What is the motor's stall current? 1N4002 is rated 1 Amp max continuous.
Not in that circuit.
(But sounds like a rather kinky Cephalopod! 
)
Nice schematic, and you are close. I am assuming D1 is for reverse polarity. I am assuming that D1 will support your load current (1A Max). I am also assuming you will be using an Arduino UNO (5V output on port). If so then eliminate U4 entirely then connect what was pin 3 to the output pin of the Arduino. D2 should not be needed as you chose an avalanche rated MOSFET. You can leave it there if you want but it should be sized to the motor; at 1A you are OK. The gate will not be fully enhanced with 5V but it should work for small motors. PWM will be fine. If the MOSFET gets hot you need to select one with a lower Vgs and or add a heatsink. If my assumptions are wrong please post information showing what you have.
True for both.
I see that the PC817 have two versions:
and
What does it mean and how do you know which one to choose?
What you guys think about this IRF520 board? Can I use it for driving the solenoid instead of building my own?
An IRF520 will require 10v VGS to properly turn ON.
FYI
And what about STP60NF06 or IRLZ44N ?
Some MOSFETs that work well.
Thanks this is great!
comparing the IRL540 with the IRLZ44N
it seems the IRL540 have a regular diode between Source and Drain while the IRLZ44N have a Zener diode between Source and Drain.
What is the difference and is it matter for the above application? (turning on and off a 12V DC motor/solenoid) ?
For an application like this, ignore the body diode .
The Vds maximum value will tell you what voltage the MOSSFET can be safely used at.
The RDS(on) rating will show you the Vgs voltages that can turn on the MOSFET.
Pay attention so you don’t exceed Vgs(max).
IRL540 Logic level MOSFET
VDS 100V
RDS(on) .11 Ω at 4V Vgs
VGS(MAX) ± 10V
for the VDS - if* the Maximum VDS is rated for 100V - the meaning is that I can control a load (DC motor, solenoid, lamp etc that is voltage is up to 100V?
What does the VGS mean? The Maximus Voltage at the gate? for opening it?
“for the VDS - is the Maximus VDS is rated for 100V - the meaning is that I can control a load (DC motor, solenoid, lamp etc that is voltage is up to 100V?”
Suggest you stay 10% under this value, i.e. 90V or less.
“What does the VGS mean? “
The voltage applied, Gate to Source.
“The Maximus Voltage at the gate?”
Do not exceed VGS maximum values, in this case no more than +10V, no less than -10V.
A zener across or voltage divider on the Gate can keep you within these levels.
for opening it?
For turning the MOSFET ON.
if using arduino (or other microcontrollers) that operate only with 5V signal I will never exceed the +-10V right?
in what condition I could exceed this voltage Vgs?
if using arduino (or other microcontrollers) that operate only with 5V signal I will never exceed the +-10V right?
Correct
Note: if you are using a 3.3V Arduino the MOSFET must show in the data sheet, it can be turned ON when VGS is 3V3.
in what condition I could exceed this voltage Vgs?
Some Sensors ‘might’ output 0V to 12V, in which case is 2V more than the MOSSFET can handle.
for using a small DC motor/solenoid with current rated of no more then 1A can I be fine omitting the optocoupler and using this circuit instead?
how much is really important having the optocoupler ?
If your inductive load current is less than 1A the circuit will work.
Opto Couplers can be used when switching speeds are (relatively) slow.
Suggest using Opto Couplers when the Arduino is far removed from the MOSFET driver.
Note there is a CTR (current transfer ratio) value in Opto Coupler data sheets that indicated the relationship between input to output current.
A good rule to always follow is to confirm the MOSFET is fully turned on by measuring the Voltage Drain to Source (VDS) with a voltmeter.
how much is considering far? something between 5 to 12 meter max is consider far?
is there a few common Optocoupler with arduino and mosfet? I understand PC817 should be good for this. Any other?
