It sounds like I have the polarity backwards. I will take another look at the data sheet in the morning and see how I missed that. I probably have a dozen or so IRF540N's. I bought them on EBAY just to experiment. I don't really have a specific project in mind, just trying to develop a little better foundation for PIC'n! John Ferrell 6241 Phillippi Rd Julian NC 27283 Phone: (336)685-9606 Dixie Competition Products NSRCA 479 AMA 4190 W8CCW "My Competition is Not My Enemy" ----- Original Message ----- From: "Chris Loiacono" To: Sent: Thursday, February 13, 2003 4:51 PM Subject: Re: [EE]: Mosfet student question. > Try this John: > It sounds like you are wanting to do some switching. I don't know how many > watts the lamp is that you mention, but the '540 will switch a fairly large > load - even larger than an auto headlamp - so it may be overkill for your > application, but should still work. > > The Source should be toward your lowest potential, or most likely your DC > ground. The load can be on either side - that is above the drain or between > the source and Gnd. > Unlike a bipolar transistor, this thing needs a positive voltage of > somewhere between 2 and 4 V, as related to the source(that's why the data > sheet labels it Vgs) for it to switch and conduct. it does not need current > at the gate the way a bipolar needs to be biased, just volatge, so think in > terms of a voltage divider tapped to bring the Gate to at least 4V if you > want all parts to work all the time. The full 12V on the gate shouldn't hurt > it, according to the data sheet, but may not be most desirable. > > If you tried them this way they should have worked. > > > Now all you have to do is figure out if you have it connected correctly and > get the > > The pinout in the IRF540 is G, D, S as viewed from the front (printed) side > with the tab away from you. The source, or pin 3 > > How many do you have, and what is your application? > > C > > > > > > May Be I have it fixed now... > > John Ferrell > > 6241 Phillippi Rd > > Julian NC 27283 > > Phone: (336)685-9606 > > Dixie Competition Products > > NSRCA 479 AMA 4190 W8CCW > > "My Competition is Not My Enemy" > > > > > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.