Help control a 12v 20A electromagnet from ardiuno

I am a bit new to arduino, I need some help with getting the project i need dow.

The basics are this - An arduino will control the output of a 1" wide electromagnet. Right now I am looking for "off/on" control.

The arduino will be powered by the standard voltages. And the magnet by a 12v 20A DC power supply. I should be able to use PWM to trigger a MOSFET which would control the electromagnet.

Pretty simple.

Questions - 1 - I have never used MOSFETS, and can't figure out how to pick them. This thing will have a low 3.5 to 5v trigger from the arduino, but must be able to take the 12v20A that is coming through the MOSFET to the electromagnet. 2 - Best way to achieve this? Like I said MOSFETS are a mystery to me, and all. I just need to get something going so that I can run that ONE magnet. Any suggestion or tutorial?

TIA

hey!

when i did that first i simulated the circuit with QUCS first: http://qucs.sourceforge.net (they have various N-MOSFETs in their database)...

e. g. 1. u could try 4 BUZ73 in parallel... :-) 2. u could try one BUZ12 (min. 30mOhm drain-source resitance)... it would waste 19.7W (59.3mOhm) with 5V at the gate... the current would be just 18.2A... 3. u could try one BUZ12 and a TL061 for voltage translation (0V/5V control voltage to 0V/12V gate voltage; i use the 3.3V for comparison at the positive input of the TL061; CAUTION: the arduino output will have inverted semantics: 5V=off, 0V=on)... it would waste 10.3W (28.3mOhm) with 12V at the gate... the current would be just 19.1A...

u should use strong flyback diodes in order to protect the voltage source...

u should be sure that turning on&off the magnet quickly doesnt cause damage to ur voltage source...

u should check if the thermal energy is removed from the circuit/magnet properly...

bye

two IRF1324S might be a good choice, too... datasheet

together they can provide a current of 19.988A according to QUCS...

There was a previous thread on mosfets. They can be very tricky to drive especially from microcontroller ports.

Try to get a logic level mosfet if you can. If not try using a transistor to drive the gate from by switching the 12 to drive the gate.

If you can get them use a mosfet driver like an IR2110 together with your power mosfets this should work.