I'm trying to switch some decently sized loads with an Arduino Nano for a project. two 200ma loads (which can be on the same circuit) and a 300ma load on a secondary circuit.
I wasn't really thinking when ordering parts and forgot to get switching mosfets of any kind. I went searching through my parts bins and the only thing I can find are 2n5486s, an N-channel JFETs.
I'm having a hard time recalling my college courses on FETs (~5 years ago) and I can't seem to find a maximum current rating for these parts.
Would I be able to use these the 2n5486s to switch these loads? I'm also trying to figure out if I can even switch it without crazy wiring since the N-channel part of it will require -5 volts.
If not, I'll probably fall back on the much less appealing 2n3904s, not sure how I'll switch the 300ma load with that though.
Those transistors are not suitable to use as switches. They are intended for use as low power RF amplifiers.
The 2N3904 is rated for Ic = 200 mA absolute maximum. Best to use a part suitable for the job. If you must, high quality switching transistors can be often be salvaged from a discarded motorized toy.
Use a simple logic level N-Channel MOSFET that has a UIS rating. Before you spend money on them you need to post a Schematic showing all power, ground and interconnections. I am not sure where you get the -5 volts for a N-channel MOSFET. The gate drive is always referenced to the Source. That -5 would make more sense if you were talking about P-Channel MOSFETs. To get the maximum current rating look at the data sheet, they all give that information.
If you google "2N5486 datasheet" you'll find they can carry 8mA or so when fully on, take
-6V to switch off worst-case, and are 400MHz VHF parts, not power switches.
gilshultz:
Use a simple logic level N-Channel MOSFET that has a UIS rating. Before you spend money on them you need to post a Schematic showing all power, ground and interconnections. I am not sure where you get the -5 volts for a N-channel MOSFET. The gate drive is always referenced to the Source. That -5 would make more sense if you were talking about P-Channel MOSFETs. To get the maximum current rating look at the data sheet, they all give that information.
The OP was talking about an n-channel JFET, not a MOSFET. JFETs are by their nature depletion-mode
only. (Actually you can get depletion mode MOSFETs as they are agnostic, but they are rare).