I’m trying to control a high-current (10W, 12V) halogen light using an IRF540 MOSFET. My circuit seems to work when I connect it to a 9V battery and a less power consuming lamp, so I don’t think I’ve done anything that fundamentally wrong. Also, as I understand it the IRF540 is rated for 100V and 28A, so that wouldn’t be the problem either, right?
I’m all new to this and would be thankful for any advice!
Most common problem with using a IRF540 MOSFET, is that it's not a logic level MOSFET, meaning an Arduino digital output set high at +5vdc is not high enough voltage to completely turn on the mosfet.
Oh, thanks! What should I look for when buying a MOSFET? Do you have any recommendations?
So many brands and models. You really have to size the MOSFET to the load and voltage you are using. Double the voltage and current being used is a good starting point for the MOSFET specs and of course getting the logic level version makes interfacing to an Arduino a simple task.
What do you think about this MOSFET? https://www1.elfa.se/data1/wwwroot/webroot/Z_DATA/07118912.pdf
Thanks for all your help!
The problem is you are using a 100V FET in a 12V application. Your on resistance (Rds(on)) is going to be high. The logic level Z44 is a much better choice. You can also get 30V FETs which will have a much lower Rds(on).
One of the best places I have found to search for FETs (and transistors) is the OnSemi website http://www.onsemi.com
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