Dear All
I have very little basic understanding of electronics. I want to make a circuit switch electromagnet to push a metal ball using an IRF3205 (55v 110Amp) mosfet please see photo
# vin circuit 36v coil 3 ohm so help me how to set voltage value (12v?) and R for Gate. if possible guide me how to calculate it. Thank you very much

 

To answer your question you need to find a datasheet for the particular MOSFET of interest. To do that you ask Google for the:

IRFP3205 datasheet

Unfortunately, the does not immediately produce any useful results. The closest immediate match is the IRF3205, which is here:

https://www.infineon.com/dgdl/Infin...N.pdf?fileId=5546d462533600a4015355def244190a
from which the following snippet is extracted.

A cursory examination reveals, Vgs(th) of 2.0 V (min) to 4.0 V (max). This is the voltage where the part begins to turn on. Rds(on) will be at a maximum of 8mΩ and fully turned on when Vgs = 10 V and Id=62 A.

Since your load is an inductor, you probably want a catch diode in parallel with the inductor to catch the voltage spike that will occur when the switch opens.

 

Set the pulse voltage at 10 volts as previously mentioned.
Rgs at 10K.
Rin not needed but OK to set at 100 ohm.

 

The first thing that must be addressed is adding a
"Free-Wheeling-Diode" across the Coil to absorb the "Flyback-Spike"
which will probably smoke your FET if not suppressed.

The Gate-to-Source-Voltage needs to be between ~10 to ~15 Volts.

The Pulse-Width may need to be longer than ~35ms,
depending upon the amount of Power that the Solenoid can deliver to
the "Metal-Ball", and the weight of the Ball, and the required speed of the Ball.

Rgs is not critical, ~10k will work just fine.

Rin will depend upon the Circuit that is driving the Gate.
It "may" not be necessary.
.
.
.

 

Dear Sir
Your help very helpful Thank you a lot
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